title: A model for cosmological simulations of galaxy formation physics

abstract:
  We present a new comprehensive model of the physics of galaxy formation
designed for large-scale hydrodynamical simulations of structure formation
using the moving mesh code AREPO. Our model includes primordial and metal line
cooling with self-shielding corrections, stellar evolution and feedback
processes, gas recycling, chemical enrichment, a novel subgrid model for the
metal loading of outflows, black hole (BH) seeding, BH growth and merging
procedures, quasar- and radio-mode feedback, and a prescription for radiative
electro-magnetic (EM) feedback from active galactic nuclei (AGN). The metal
mass loading of outflows can be adjusted independently of the wind mass
loading. This is required to simultaneously reproduce the stellar mass content
of low mass haloes and their gas oxygen abundances. Radiative EM AGN feedback
is implemented assuming an average spectral energy distribution and a
luminosity-dependent scaling of obscuration effects. This form of feedback
suppresses star formation more efficiently than continuous thermal quasar-mode
feedback alone, but is less efficient than mechanical radio-mode feedback in
regulating star formation in massive haloes. We contrast simulation predictions
for different variants of our galaxy formation model with key observations. Our
best match model reproduces, among other things, the cosmic star formation
history, the stellar mass function, the stellar mass - halo mass relation, g-,
r-, i-, z-band SDSS galaxy luminosity functions, and the Tully-Fisher relation.
We can achieve this success only if we invoke very strong forms of stellar and
AGN feedback such that star formation is adequately reduced in both low and
high mass systems. In particular, the strength of radio-mode feedback needs to
be increased significantly compared to previous studies to suppress efficient
cooling in massive, metal-enriched haloes.


title: Here be Dragons: The Unexplored Continents of the CMSSM

abstract:
  The Higgs boson mass and the abundance of dark matter constrain the
CMSSM/mSUGRA supersymmetry breaking inputs. A complete map of the CMSSM that is
consistent with these two measured quantities is provided. Various
"continents," consisting of non-excluded models, can be organized by their dark
matter dynamics. The following mechanisms manifest: well-tempering, resonant
pseudo-scalar Higgs annihilation, neutralino/stau coannihilations and
neutralino/stop coannihilations. Benchmark models are chosen in order to
characterize the viable regions. The expected visible signals of each are
described, demonstrating a wide range of predictions for the 13 TeV LHC and a
high degree of complementarity between dark matter and collider experiments.
The parameter space spans a finite volume, which can be probed in its entirety
with experiments currently under consideration.


title:
The Growth of Cool Cores and Evolution of Cooling Properties in a Sample
  of 83 Galaxy Clusters at 0.3 < z < 1.2 Selected from the SPT-SZ Survey

abstract:
  We present first results on the cooling properties derived from Chandra X-ray
observations of 83 high-redshift (0.3 < z < 1.2) massive galaxy clusters
selected by their Sunyaev-Zel'dovich signature in the South Pole Telescope
data. We measure each cluster's central cooling time, central entropy, and mass
deposition rate, and compare to local cluster samples. We find no significant
evolution from z~0 to z~1 in the distribution of these properties, suggesting
that cooling in cluster cores is stable over long periods of time. We also find
that the average cool core entropy profile in the inner ~100 kpc has not
changed dramatically since z ~ 1, implying that feedback must be providing
nearly constant energy injection to maintain the observed "entropy floor" at
~10 keV cm^2. While the cooling properties appear roughly constant over long
periods of time, we observe strong evolution in the gas density profile, with
the normalized central density (rho_0/rho_crit) increasing by an order of
magnitude from z ~ 1 to z ~ 0. When using metrics defined by the inner surface
brightness profile of clusters, we find an apparent lack of classical, cuspy,
cool-core clusters at z > 0.75, consistent with earlier reports for clusters at
z > 0.5 using similar definitions. Our measurements indicate that cool cores
have been steadily growing over the 8 Gyr spanned by our sample, consistent
with a constant, ~150 Msun/yr cooling flow that is unable to cool below
entropies of 10 keV cm^2 and, instead, accumulates in the cluster center. We
estimate that cool cores began to assemble in these massive systems at z ~ 1,
which represents the first constraints on the onset of cooling in galaxy
cluster cores. We investigate several potential biases which could conspire to
mimic this cool core evolution and are unable to find a bias that has a similar
redshift dependence and a substantial amplitude.


title:
Self-accelerating Massive Gravity: How Zweibeins Walk through
  Determinant Singularities

abstract:
  The theory of massive gravity possesses ambiguities when the spacetime metric
evolves far from the non-dynamical fiducial metric used to define it. We
explicitly construct a spherically symmetric example case where the metric
evolves to a coordinate-independent determinant singularity which does not
exist in the initial conditions. Both the metric and the vierbein formulation
of the theory are ill-defined at this point. In unitary gauge, the chart of the
spacetime ends at this point and does not cover the full spacetime whereas the
spherically symmetric vierbeins, or zweibeins, of the fiducial metric become
non-invertible and do not describe a valid metric. Nonetheless it is possible
to continuously join a zweibein solution on the other side of the singularity
which picks one of the degenerate solutions of the metric square root. This
continuous solution is not the choice conventionally made in the previous
literature. We also show that the Stueckelberg equations of motion on the
self-accelerating branch prevent solutions from evolving to a more pathological
situation in which the spacetime vierbeins lack a crucial symmetry with the
fiducial vierbeins and real square roots fail to exist.


title: Halo Stochasticity from Exclusion and non-linear Clustering

abstract:
  The clustering of galaxies in ongoing and upcoming galaxy surveys contains a
wealth of cosmological information, but extracting this information is a
non-trivial task since galaxies and their host haloes are stochastic tracers of
the matter density field. This stochasticity is usually modeled as Poisson shot
noise, which is constant as a function of wavenumber with amplitude given by
1/n, where n is the number density of galaxies. Here we use dark matter haloes
in N-body simulations to show evidence for deviations from this simple
behaviour and develop models that explain the behaviour of the large scale
stochasticity. First, haloes are extended, non-overlapping objects, i.e., their
correlation function needs to go to -1 on small scales. This leads to a
negative correction to the stochasticity relative to the Poisson value at low
wavenumber k, decreasing to zero for wavenumbers large compared to the inverse
exclusion scale. Second, haloes show a non-linear enhancement of clustering
outside the exclusion scale, leading to a positive stochasticity correction.
Both of these effects go to zero for high-k, making the stochasticity scale
dependent even for k<0.1 h/Mpc. We show that the corrections in the low-k
regime are the same in Eulerian and Lagrangian space, but that the transition
scale is pushed to smaller scales for haloes observed at present time, relative
to the initial conditions. These corrections vary with halo mass and redshift.
We also discuss simple applications of these effects to the galaxy samples with
non-vanishing satellite fraction, where the stochasticity can again deviate
strongly from the fiducial Poisson expectation. Overall these effects affect
the clustering of galaxies at a level of a few percent even on very large
scales and need to be modelled properly if we want to extract high precision
cosmological information from the upcoming galaxy surveys.


title:
Singularity of the London penetration depth at quantum critical points
  in superconductors

abstract:
  We present a general theory of the singularity in the London penetration
depth at symmetry-breaking and topological quantum critical points within a
superconducting phase. While the critical exponents, and ratios of amplitudes
on the two sides of the transition are universal, an overall sign depends upon
the interplay between the critical theory and the underlying Fermi surface. We
determine these features for critical points to spin density wave and nematic
ordering, and for a topological transition between a superconductor with
$\mathbb{Z}_2$ fractionalization and a conventional superconductor. We note
implications for recent measurements of the London penetration depth in
BaFe$_2$(As$_{1-x}$P$_x$)$_2$ (Hashimoto et al., Science 336, 1554 (2012)).

categories: cond-mat.str-el cond-mat.stat-mech cond-mat.supr-con hep-th


title: Cosmic evolution from phase transition of 3-dimensional flat space

abstract:
  Flat space cosmology spacetimes are exact time-dependent solutions of
3-dimensional gravity theories, such as Einstein gravity or topologically
massive gravity. We exhibit a novel kind of phase transition between these
cosmological spacetimes and the Minkowski vacuum. At sufficiently high
temperature (rotating) hot flat space tunnels into a universe described by flat
space cosmology.


title: Solar constraints on hidden photons re-visited

abstract:
  We re-examine solar emission of hidden photons gamma' (mass m) caused by
kinetic mixing. We calculate the emission rate with thermal field theory
methods and with a kinetic equation that includes "flavor oscillations" and
photon absorption and emission by the thermal medium. In the resonant case both
methods yield identical emission rates which, in the longitudinal channel, are
enhanced by a factor w_P^2/m^2 (plasma frequency w_P) in agreement with An,
Pospelov and Pradler (2013). The Sun must not emit more energy in a "dark
channel" than allowed by solar neutrino measurements, i.e., not more than 10%
of its photon luminosity. Together with the revised emission rate, this
conservative requirement implies a bound \chi<4\times 10^-12 eV/m for the
kinetic mixing parameter. This is the most restrictive stellar limit below m ~
3 eV, whereas for larger masses the transverse channel dominates together with
limits from other stars. A recent analysis of XENON10 data marginally improves
the solar limit, leaving open the opportunity to detect solar hidden photons
with future large-scale dark matter experiments. Detecting low-mass hidden
photons with the ALPS-II photon-regeneration experiment also remains possible.


title:
Natural, R-parity violating supersymmetry and horizontal flavor
  symmetries

abstract:
  The absence so far of any supersymmetric signals at the LHC pushes towards a
rethinking of the assumptions underlying the MSSM. Because the large missing
$E_T$ searches are inadequate to detect a LSP decaying within the detector,
R-parity violating supersymmetry is still a good candidate for low energy,
natural supersymmetry. We show that, in Froggatt-Nielsen-like models of
horizontal symmetries, specific textures for the R-parity violating couplings
are dictated by the symmetry, with the largest coupling involving the third
generation fields. Lepton number can be an accidental symmetry of the
renormalizable superpotential and barion number violation is given by a $\bar
u\bar d\bar d$ operator. The collider phenomenology then mimics the main
features of MFV R-parity violating supersymmetry. The LSP can evade current LHC
supersymmetry searches, is allowed to be well below 1 TeV and at the same time
all the constraints from proton decay and other low energy decays can be
satisfied; in particular, dimension five operators allowed by R-parity but
dangerous for the proton are under control, while neutrino masses are generated
by the Weinberg operator. Assuming sub TeV ({\it natural}) superpartners, we
obtain both upper and lower limits on the magnitude of the dominant R-parity
violating coupling: a lower limit of order $10^{-9}$ arises from null LHC
searches on R-hadrons and heavy stable charged particles, while a upper limit
of order $10^{-3}$ follows from constraints on low-energy flavor changing
neutral currents. Displaced vertices are predicted in the lower end of this
range.


title:
Alignment Between Flattened Protostellar Infall Envelopes and Ambient
  Magnetic Fields

abstract:
  We present 350 micron polarization observations of four low-mass cores
containing Class 0 protostars: L483, L1157, L1448-IRS2, and Serp-FIR1. This is
the second paper in a larger survey aimed at testing magnetically regulated
models for core-collapse. One key prediction of these models is that the mean
magnetic field in a core should be aligned with the symmetry axis (minor axis)
of the flattened YSO inner envelope (aka pseudodisk). Furthermore, the field
should exhibit a pinched or hour-glass shaped morphology as gravity drags the
field inward towards the central protostar. We combine our results for the four
cores with results for three similar cores that were published in the first
paper from our survey. An analysis of the 350 micron polarization data for the
seven cores yields evidence of a positive correlation between mean field
direction and pseudodisk symmetry axis. Our rough estimate for the probability
of obtaining by pure chance a correlation as strong as the one we found is
about 5%. In addition, we combine together data for multiple cores to create a
source-averaged magnetic field map having improved signal-to-noise ratio, and
this map shows good agreement between mean field direction and pseudodisk axis
(they are within 15 degrees). We also see hints of a magnetic pinch in the
source-averaged map. We conclude that core-scale magnetic fields appear to be
strong enough to guide gas infall, as predicted by the magnetically regulated
models. Finally, we find evidence of a positive correlation between core
magnetic field direction and bipolar outflow axis.


title: Mapping dust through emission and absorption in nearby galaxies

abstract:
  Dust has long been identified as a barrier to measuring inherent galaxy
properties. However, the link between dust and attenuation is not
straightforward and depends on both the amount of dust and its distribution.
Herschel imaging of nearby galaxies undertaken as part of the KINGFISH project
allows us to map the dust as seen in emission with unprecedented sensitivity
and ~1 kpc resolution. We present here new optical integral field unit
spectroscopy for eight of these galaxies that provides complementary 100-200 pc
scale maps of the dust attenuation through observation of the reddening in both
the Balmer decrement and the stellar continuum. The stellar continuum
reddening, which is systematically less than that observed in the Balmer
decrement, shows no clear correlation with the dust, suggesting that the
distribution of stellar reddening acts as a poor tracer of the overall dust
content. The brightest HII regions are observed to be preferentially located in
dusty regions, and we do find a correlation between the Balmer line reddening
and the dust mass surface density for which we provide an empirical relation.
Some of the high-inclination systems in our sample exhibit high extinction, but
we also find evidence that unresolved variations in the dust distribution on
scales smaller than 500 pc may contribute to the scatter in this relation. We
caution against the use of integrated A_V measures to infer global dust
properties.


title:
Wigner-Poisson statistics of topological transitions in a Josephson
  junction

abstract:
  The phase-dependent bound states (Andreev levels) of a Josephson junction can
cross at the Fermi level, if the superconducting ground state switches between
even and odd fermion parity. The level crossing is topologically protected, in
the absence of time-reversal and spin-rotation symmetry, irrespective of
whether the superconductor itself is topologically trivial or not. We develop a
statistical theory of these topological transitions in an N-mode quantum-dot
Josephson junction, by associating the Andreev level crossings with the real
eigenvalues of a random non-Hermitian matrix. The number of topological
transitions in a 2pi phase interval scales as sqrt(N) and their spacing
distribution is a hybrid of the Wigner and Poisson distributions of
random-matrix theory.


title:
Balance among gravitational instability, star formation, and accretion
  determines the structure and evolution of disk galaxies

abstract:
  Over the past 10 Gyr, star-forming galaxies have changed dramatically, from
clumpy and gas rich, to rather quiescent stellar-dominated disks with specific
star formation rates lower by factors of a few tens. We present a general
theoretical model for how this transition occurs, and what physical processes
drive it, making use of 1D axisymmetric thin disk simulations with an improved
version of the Gravitational Instability-Dominated Galaxy Evolution Tool
(GIDGET) code. We show that at every radius galaxies tend to be in a slowly
evolving equilibrium state wherein new accretion is balanced by star formation,
galactic winds, and radial transport of gas through the disk by gravitational
instability (GI) -driven torques. The gas surface density profile is determined
by which of these terms are in balance at a given radius - direct accretion is
balanced by star formation and galactic winds near galactic centers, and by
transport at larger radii. We predict that galaxies undergo a smooth transition
from a violent disk instability phase to secular evolution. This model provides
a natural explanation for the high velocity dispersions and large clumps in z~2
galaxies, the growth and subsequent quenching of bulges, and features of the
neutral gas profiles of local spiral galaxies.


title:
Resolving the optical emission lines of Lya blob 'B1' at z=2.38: another
  hidden quasar

abstract:
  We have used the SINFONI near-infrared integral field unit on the VLT to
resolve the optical emission line structure of one of the brightest (L~1e44
erg/s) and nearest (z=2.38) of all Lya blobs (LABs). The target, known in the
literature as object 'B1' (Francis et al. 1996), lies at a redshift where the
main optical emission lines are accessible in the observed near-infrared. We
detect luminous [OIII]4959,5007A and Ha emission with a spatial extent of at
least 32x40 kpc (4"x5"). The dominant optical emission line component shows
relatively broad lines (600-800 km/s, FWHM) and line ratios consistent with
AGN-photoionization. The new evidence for AGN photoionization, combined with
previously detected CIV and luminous, warm infrared emission, suggest that B1
is the site of a hidden quasar. This is confirmed by the fact that [OII] is
relatively weak compared to [OIII] (extinction-corrected [OIII]/[OII] of about
3.8), which is indicative of a high, Seyfert-like ionization parameter. From
the [OIII] luminosity we infer a bolometric AGN luminosity of ~3e46 erg/s, and
further conclude that the obscured AGN may be Compton-thick given existing
X-ray limits. The large line widths observed are consistent with clouds moving
within the narrow line region of a luminous QSO. The AGN scenario is capable of
producing sufficient ionizing photons to power the Lya, even in the presence of
dust. By performing a census of similar objects in the literature, we find that
virtually all luminous LABs harbor obscured quasars. Based on simple duty-cycle
arguments, we conclude that AGN are the main drivers of the Lya in LABs rather
than the gravitational heating and subsequent cooling suggested by cold stream
models. We also conclude that the empirical relation between LABs and overdense
environments at high redshift must be due to a more fundamental correlation
between AGN (or massive galaxies) and environment.


title:
Physics of a partially ionized gas relevant to galaxy formation
  simulations -- the ionization potential energy reservoir

abstract:
  Simulation codes for galaxy formation and evolution take on board as many
physical processes as possible beyond the standard gravitational and
hydrodynamical physics. Most of this extra physics takes place below the
resolution level of the simulations and is added in a sub-grid fashion.
However, these sub-grid processes affect the macroscopic hydrodynamical
properties of the gas and thus couple to the on-grid physics that is explicitly
integrated during the simulation. In this paper, we focus on the link between
partial ionization and the hydrodynamical equations. We show that the energy
stored in ions and free electrons constitutes a potential energy term which
breaks the linear dependence of the internal energy on temperature. Correctly
taking into account ionization hence requires modifying both the equation of
state and the energy-temperature relation. We implemented these changes in the
cosmological simulation code Gadget2. As an example of the effects of these
changes, we study the propagation of Sedov-Taylor shock waves through an
ionizing medium. This serves as a proxy for the absorption of supernova
feedback energy by the interstellar medium. Depending on the density and
temperature of the surrounding gas, we find that up to 50% of the feedback
energy is spent ionizing the gas rather than heating it. Thus, it can be
expected that properly taking into account ionization effects in galaxy
evolution simulations will drastically reduce the effects of thermal feedback.
To the best of our knowledge, this potential energy term is not used in current
simulations of galaxy formation and evolution.


title:
Bose-Einstein Condensation versus Dicke-Hepp-Lieb Transition in an
  Optical Cavity

abstract:
  We provide an exact solution for the interplay between Bose-Einstein
condensation and the Dicke-Hepp-Lieb self-organization transition of an ideal
Bose gas trapped inside a single-mode optical cavity and subject to a
transverse laser drive. Based on an effective action approach, we determine the
full phase diagram at arbitrary temperature, which features a bi-critical point
where the transitions cross. We calculate the dynamically generated band
structure of the atoms and the associated supression of the critical
temperature for Bose-Einstein condensation in the phase with a spontaneous
periodic density modulation. Moreover, we determine the evolution of the
polariton spectrum due to the coupling of the cavity photons and the atomic
field near the self-organization transition, which is quite different above or
below the Bose-Einstein condensation temperature. At low temperatures, the
critical value of the Dicke-Hepp-Lieb transition decreases with temperature and
thus thermal fluctuations can enhance the tendency to a periodic arrangement of
the atoms.


title: Topological resolution of gauge theory singularities

abstract:
  Some gauge theories with Coulomb branches exhibit singularities in
perturbation theory, which are usually resolved by nonperturbative physics. In
string theory this corresponds to the resolution of timelike singularities near
the core of orientifold planes by effects from F or M theory. We propose a new
mechanism for resolving Coulomb branch singularities in three dimensional gauge
theories, based on Chern-Simons interactions. This is illustrated in a
supersymmetric SU(2) Yang-Mills-Chern-Simons theory. We calculate the one loop
corrections to the Coulomb branch of this theory and find a result that
interpolates smoothly between the high energy metric (that would exhibit the
singularity) and a regular singularity-free low energy result. We suggest
possible applications to singularity resolution in string theory and speculate
a relationship to a similar phenomenon for the orientifold six-plane in massive
IIA supergravity.


title: Perturbations in Chromo-Natural Inflation

abstract:
  Chromo-Natural Inflation is the first worked example of a model of inflation
in which slow-roll inflation is achieved by "magnetic drift" as opposed to
Hubble friction. In this work, we give an account of the perturbations at
linear order in this model. Our analysis uncovers two novel phenomena. First,
the amplitude of scalar curvature perturbations is not directly tied to the
shape of the inflationary potential. This allows the theory to violate na\"ive
formulations of the Lyth bound. Second, the tensor sector of the theory is
significantly altered from the usual case: the non-Abelian gauge field
perturbations have a tensor degree of freedom. One chirality of the this tensor
can be exponentially enhanced by a temporary instability near horizon crossing;
this chiral instability exists because of the classical gauge field background,
which violates parity. These tensor fluctuations of the gauge field also couple
to gravitational waves at linear order in perturbation theory and source a
chiral spectrum of gravitational waves. This spectrum can be exponentially
enhanced over the usual inflationary spectrum due to the instability in the
gauge sector. These new features cause the theory in its present form to be in
significant tension with current observational data. This is because the new
scalar physics leads to a significant reddening of the spectral tilt in the
same region of parameter space where the exponential enhancement of the
gravitational wave amplitude is small enough to satisfy current constraints on
the tensor-to-scalar index. Hence, the model either predicts a spectral tilt
that is too red, or it overproduces gravitational waves, or both.


title: Gribov horizon beyond the Landau gauge

abstract:
  Gribov and Zwanziger proposed a modification of Yang-Mills theory in order to
cure the Gribov copy problem. We employ field-dependent BRST transformations to
generalize the Gribov-Zwanziger model from the Landau gauge to general R_xi
gauges. The Gribov horizon functional is presented in explicit form, in both
the non-local and local variants. Finally, we show how to reach any given gauge
from the Landau one.


title:
A first look at transition amplitudes in (2+1)-dimensional causal
  dynamical triangulations

abstract:
  We study a lattice regularization of the gravitational path integral--causal
dynamical triangulations--for (2+1)-dimensional Einstein gravity with positive
cosmological constant in the presence of past and future spacelike boundaries
of fixed intrinsic geometries. For spatial topology of a 2-sphere, we determine
the form of the Einstein-Hilbert action supplemented by the
Gibbons-Hawking-York boundary terms within the Regge calculus of causal
triangulations. Employing this action we numerically simulate a variety of
transition amplitudes from the past boundary to the future boundary. To the
extent that we have so far investigated them, these transition amplitudes
appear consistent with the gravitational effective action previously found to
characterize the ground state of quantum spacetime geometry within the
Euclidean de Sitter-like phase. Certain of these transition amplitudes
convincingly demonstrate that the so-called stalks present in this phase are
numerical artifacts of the lattice regularization, seemingly indicate that the
quantization technique of causal dynamical triangulations differs in detail
from that of the no-boundary proposal of Hartle and Hawking, and possibly
represent the first numerical simulations of portions of temporally unbounded
quantum spacetime geometry within the causal dynamical triangulations approach.
We also uncover tantalizing evidence suggesting that Lorentzian not Euclidean
de Sitter spacetime dominates the ground state on sufficiently large scales.


title: A Potential Super-Venus in the Kepler-69 System

abstract:
  Transiting planets have greatly expanded and diversified the exoplanet field.
These planets provide greater access to characterization of exoplanet
atmospheres and structure. The Kepler mission has been particularly successful
in expanding the exoplanet inventory, even to planets smaller than the Earth.
The orbital period sensitivity of the Kepler data is now extending into the
Habitable Zones of their host stars, and several planets larger than the Earth
have been found to lie therein. Here we examine one such proposed planet,
Kepler-69c. We provide new orbital parameters for this planet and an in-depth
analysis of the Habitable Zone. We find that, even under optimistic conditions,
this 1.7 R$_\oplus$ planet is unlikely to be within the Habitable Zone of
Kepler-69. Furthermore, the planet receives an incident flux of 1.91 times the
solar constant, which is similar to that received by Venus. We thus suggest
that this planet is likely a super-Venus rather than a super-Earth in terms of
atmospheric properties and habitability, and we propose follow-up observations
to disentangle the ambiguity.


title: Towards a unified treatment of gravitational-wave data analysis

abstract:
  We present a unified description of gravitational-wave data analysis that
unites the template-based analysis used to detect deterministic signals from
well-modeled sources, such as binary-black-hole mergers, with the
cross-correlation analysis used to detect stochastic gravitational-wave
backgrounds. We also discuss the connection between template-based analyses and
those that target poorly-modeled bursts of gravitational waves, and suggest a
new approach for detecting burst signals.


title:
Phase Transition and Thermal Order-by-Disorder in the Pyrochlore Quantum
  Antiferromagnet Er2Ti2O7: a High-Temperature Series Expansion Study

abstract:
  Several rare earth magnetic pyrochlore materials are well modeled by a
spin-1/2 quantum Hamiltonian with anisotropic exchange parameters Js. For the
Er2Ti2O7 material, the Js were recently determined from high-field inelastic
neutron scattering measurements. Here, we perform high-temperature (T) series
expansions to compute the thermodynamic properties of this material using these
Js. Comparison with experimental data show that the model describes the
material very well including the finite temperature phase transition to an
ordered phase at Tc~1.2 K. We show that high temperature expansions give
identical results for different q=0 xy order parameter susceptibilities up to
8th order in \beta=1/T (presumably to all orders in \beta). Conversely, a
non-linear susceptibility related to the 6th power of the order parameter
reveals a thermal order-by-disorder selection of the same non-colinear \psi_2
state as found in Er2Ti2O7.


title: GRO J1008-57: an (almost) predictable transient X-ray binary

abstract:
  A study of archival RXTE, Swift, and Suzaku pointed observations of the
transient high mass X-ray binary GRO J1008-57 is presented. A new orbital
ephemeris based on pulse arrival timing shows times of maximum luminosities
during outbursts of GRO J1008-57 to be close to periastron at orbital phase
-0.03. This makes the source one of a few for which outburst dates can be
predicted with very high precision.
  Spectra of the source in 2005, 2007, and 2011 can be well described by a
simple power law with high energy cutoff and an additional black body at lower
energies. The photon index of the power law and the black body flux only depend
on the 15-50 keV source flux. No apparent hysteresis effects are seen. These
correlations allow to predict the evolution of the pulsar's X-ray spectral
shape over all outbursts as a function of just one parameter, the source's
flux. If modified by an additional soft component, this prediction even holds
during GRO J1008-57's 2012 type II outburst.


title: Zoology of heterotic supercurrent supermultiplets in d=2

abstract:
  We present various (0,2) heterotic supercurrent supermultiplets in (1+1)
dimensional quantum field theories. From the minimal supercurrent
supermultiplets, we deduce conditions on symmetry enhancement such as Lorentz
invariance, (chiral) dilatation invariance, R-invariance, (chiral) conformal
invariance and their various combinations. Our construction covers many
interesting and/or exotic possibilities such as Lifshitz supersymmetry and
warped superconformal algebra. We also discuss the corresponding supergravity
by gauging the supercurrent supermultiplet. In particular, we propose a novel
class of heterotic supergravity based on the virial supercurrent.


title: Temporal networks: slowing down diffusion by long lasting interactions

abstract:
  Interactions among units in complex systems occur in a specific sequential
order thus affecting the flow of information, the propagation of diseases, and
general dynamical processes. We investigate the Laplacian spectrum of temporal
networks and compare it with that of the corresponding aggregate network.
First, we show that the spectrum of the ensemble average of a temporal network
has identical eigenmodes but smaller eigenvalues than the aggregate networks.
In large networks without edge condensation, the expected temporal dynamics is
a time-rescaled version of the aggregate dynamics. Even for single sequential
realizations, diffusive dynamics is slower in temporal networks. These
discrepancies are due to the noncommutability of interactions. We illustrate
our analytical findings using a simple temporal motif, larger network models
and real temporal networks.


title: Spectroscopic indication of suprathermal ions in the solar corona

abstract:
  Using spectroscopic data, we support the possibility of suprathermal
distributions of coronal ions by fitting the equivalent kappa functions to
their emission line profiles. We fit different kappa and Gaussian model
functions to line profiles of the strong Fe xv line at 284.16 Angstroms, across
two large-field spectroscopic rasters taken in a solar active region. Both
single- and double-component Gaussian models are applied, as well as two kappa
models, one with a free width parameter allowing for and the other with a
constrained width that precludes "microturbulence". We then compare the
goodness of fit of the computed best fits for each model. The kappa
distribution is a generalization, or superset, of the Maxwellian, so they are
able to fit line profiles more precisely than a Gaussian. In most of the data,
the best-fit kappa model produces much lower residuals across the profile than
any single Gaussian and sometimes double Gaussian. Most importantly, the
distribution of estimated kappa values is found to lie mostly in the low-kappa
range, implying ion populations far from Maxwellian. Even when the width is
removed as a free parameter of fit, the kappa model is still able to fit the
data credibly, again with low best-fit values of kappa. We find the shape of
the Fe xv line, in the vast majority of the data analyzed, to be indicative of
a highly suprathermal ion population.


title:
On the Origin of Lopsidedness in Galaxies as Determined from the Spitzer
  Survey of Stellar Structure in Galaxies (S4G)

abstract:
  We study the m=1 distortions (lopsidedness) in the stellar components of 167
nearby galaxies that span a wide range of morphologies and luminosities. We
confirm the previous findings of 1) a high incidence of lopsidedness in the
stellar distributions, 2) increasing lopsidedness as a function of radius out
to at least 3.5 exponential scale lengths, and 3) greater lopsidedness, over
these radii, for galaxies of later type and lower surface brightness.
Additionally, the magnitude of the lopsidedness 1) correlates with the
character of the spiral arms (stronger arm patterns occur in galaxies with less
lopsidedness), 2) is not correlated with the presence or absence of a bar, or
the strength of the bar when one is present, 3) is inversely correlated to the
stellar mass fraction, f_*, within one radial scale length, and 4) correlates
directly with f_* measured within the radial range over which we measure
lopsidedness. We interpret these findings to mean that lopsidedness is a
generic feature of galaxies and does not, generally, depend on a rare event,
such as a direct accretion of a satellite galaxy onto the disk of the parent
galaxy. While lopsidedness may be caused by several phenomena, moderate
lopsidedness (<A_1>_i + <A_1>_o)/2 < 0.3) is likely to reflect halo asymmetries
to which the disk responds or a gravitationally self-generated mode . We
hypothesize that the magnitude of the stellar response depends both on how
centrally concentrated the stars are with respect to the dark matter and
whether there are enough stars in the region of the lopsidedness that
self-gravity is dynamically important.


title:
Radio Constraints on Heavily-Obscured Star-Formation within Dark
  Gamma-Ray Burst Host Galaxies

abstract:
  Highly dust-obscured starbursting galaxies (submillimeter galaxies and their
ilk) represent the most extreme sites of star-formation in the distant universe
and contribute significantly to overall cosmic star-formation beyond z>1.5.
Some stars formed in these environments may also explode as GRBs and contribute
to the population of "dark" bursts. Here we present VLA wideband
radio-continuum observations of 15 heavily dust-obscured Swift GRBs to search
for radio synchrotron emission associated with intense star-formation in their
host galaxies. Most of these targets (11) are not detected. Of the remaining
four objects, one detection is marginal and for two others we cannot yet rule
out the contribution of a long-lived radio afterglow. The final detection is
secure, but indicates a star-formation rate roughly consistent with the
UV-inferred value. Most galaxies hosting obscured GRBs are therefore not
forming stars at extreme rates, and the amount of optical extinction seen along
a GRB afterglow sightline does not clearly correlate with the likelihood that
the host has a sufficiently high star-formation rate to be radio-detectable.
While some submillimeter galaxies do readily produce GRBs, these GRBs are often
not heavily obscured - suggesting that the outer (modestly obscured) parts of
these galaxies overproduce GRBs and the inner (heavily obscured) parts
underproduce GRBs relative to their respective contributions to star-formation,
hinting at strong chemical or IMF gradients within these systems.


title:
Measurement of the distributions of event-by-event flow harmonics in
  lead--lead collisions at sqrt(s_NN)=2.76 TeV with the ATLAS detector at the
  LHC

abstract:
  The distributions of event-by-event harmonic flow coefficients v_n for n=2-4
are measured in sqrt(s_NN)=2.76 TeV Pb+Pb collisions using the ATLAS detector
at the LHC. The measurements are performed using charged particles with
transverse momentum pT> 0.5 GeV and in the pseudorapidity range |eta|<2.5 in a
dataset of approximately 7 ub^-1 recorded in 2010. The shapes of the v_n
distributions are described by a two-dimensional Gaussian function for the
underlying flow vector in central collisions for v_2 and over most of the
measured centrality range for v_3 and v_4. Significant deviations from this
function are observed for v_2 in mid-central and peripheral collisions, and a
small deviation is observed for v_3 in mid-central collisions. It is shown that
the commonly used multi-particle cumulants are insensitive to the deviations
for v_2. The v_n distributions are also measured independently for charged
particles with 0.5<pT<1 GeV and pT>1 GeV. When these distributions are rescaled
to the same mean values, the adjusted shapes are found to be nearly the same
for these two pT ranges. The v_n distributions are compared with the
eccentricity distributions from two models for the initial collision geometry:
a Glauber model and a model that includes corrections to the initial geometry
due to gluon saturation effects. Both models fail to describe the experimental
data consistently over most of the measured centrality range.


title: On the Variational Regularity of Cameron-Martin paths

abstract:
  It is a well-known fact that finite rho-variation of the covariance (in 2D
sense) of a general Gaussian process implies finite rho-variation of
Cameron-Martin paths. In the special case of fractional Brownian motion (think:
2H=1/rho), in the rougher than Brownian regime, a sharper result holds thanks
to a Besov-type embedding [Friz-Victoir, JFA, 2006]. In the present note we
give a general result which closes this gap. We comment on the importance of
this result for various applications.


title: Linear combinations of frame generators in systems of translates

abstract:
  A finitely generated shift invariant space $V$ is a closed subspace of
$L^2(\R^d)$ that is generated by the integer translates of a finite number of
functions. A set of frame generators for $V$ is a set of functions whose
integer translates form a frame for $V$. In this note we give necessary and
sufficient conditions in order that a minimal set of frame generators can be
obtained by taking linear combinations of the given frame generators.
Surprisingly the results are very different to the recently studied case when
the property to be a frame is not required.


title: Kinematic classification of non-interacting spiral galaxies

abstract:
  Using neutral hydrogen (HI) rotation curves of 79 galaxies, culled from the
literature, as well as measured from HI data, we present a method for
classifying disk galaxies by their kinematics. In order to investigate
fundamental kinematic properties we concentrate on non-interacting spiral
galaxies. We employ a simple parameterized form for the rotation curve in order
to derive the three parameters: the maximum rotational velocity, the turnover
radius and a measure of the slope of the rotation curve beyond the turnover
radius. Our approach uses the statistical Hierarchical Clustering method to
guide our division of the resultant 3D distribution of galaxies into five
classes. Comparing the kinematic classes in this preliminary classification
scheme to a number of galaxy properties we find that our class containing
galaxies with the largest rotational velocities has a mean morphological type
of Sb/Sbc while the other classes tend to later types. Other trends also
generally agree with those described by previous researchers. In particular we
confirm correlations between increasing maximum rotational velocity and the
following observed properties: increasing brightness in B-band, increasing size
of the optical disk (D_25) and increasing star formation rate (as derived using
radio continuum data). Our analysis also suggests that lower velocities are
associated with a higher ratio of the HI mass over the dynamical mass.
Additionally, three galaxies exhibit a drop in rotational velocity amplitude of
>~ 20% after the turnover radius. However recent investigations suggest that
they have interacted with minor companions which is a common cause for
declining rotation curves. (Figures 12, 14, 16 and 17 are interactive in the
electronic pdf version of this paper.)


title: Do quiescent and active galaxies have different M_BH-sigma relations?

abstract:
  To investigate the validity of the assumption that quiescent galaxies and
active galaxies follow the same black hole mass - stellar velocity dispersion
relation, as required for the calibration of M_BH estimators for broad line
AGNs, we determine and compare the M-sigma relations, respectively, for
quiescent and active galaxies. For the quiescent galaxy sample, composed of 72
dynamical M_BH measurements, we update sigma for 28 galaxies using homogeneous
H-band measurements that are corrected for galaxy rotation. For active
galaxies, we collect 25 reverberation-mapped AGNs and improve sigma measurement
for two objects . Combining the two samples, we determine the virial factor
$f$, first by scaling the active galaxy sample to the M-sigma relation of
quiescent galaxies, and second by simultaneously fitting the quiescent and
active galaxy samples, as f=5.1_{-1.1}^{+1.5} and f=5.9_{-1.5}^{+2.1},
respectively. The M-sigma relation of active galaxies appears to be shallower
than that of quiescent galaxies. However, the discrepancy is caused by a
difference in the accessible M_BH distribution at given sigma, primarily due to
the difficulty of measuring reliable stellar velocity dispersion for the host
galaxies of luminous AGNs. Accounting for the selection effects, we find that
active and quiescent galaxies are consistent with following intrinsically the
same M-sigma relation.


title:
A study on analytic parametrizations for proton-proton cross-sections
  and asymptotia

abstract:
  A comparative study on some representative parametrizations for the total and
elastic cross-sections as a function of energy is presented. The dataset
comprises pp and \bar{p}p scattering in the c.m energy interval 5 GeV-8 TeV.
The parametrization for the total cross-section at low and intermediate
energies follows the usual reggeonic structure (non-degenerate trajectories).
For the leading high-energy pomeron contribution, we consider three distinct
analytic parametrizations: either a power (P) law, or a log-squared (L2) law or
a log-raised-to-gamma (Lgamma) law, where the exponent gamma is treated as a
real free fit parameter. The parametrizations are also extended to fit the
elastic (integrated) cross-section data in the same energy interval. Our main
conclusions are the following: the data reductions with the logarithmic laws
show strong dependence on the unknown energy scale involved, which is treated
here either as a free parameter or fixed at the energy threshold; the fit
results with the P law, the L2 law (free scale) and the Lgamma law (fixed scale
and exponent gamma above 2) are all consistent within their uncertainties and
with the experimental data up to 7 TeV, but they partially underestimate the
high-precision TOTEM measurement at 8 TeV; once compared with these results,
the L2 law with fixed scale is less consistent with the data and, in the case
of a free scale, this pomeron contribution decreases as the energy increases
below the scale factor (which lies above the energy cutoff); in all cases
investigated, the predictions for the asymptotic ratio between the elastic and
total cross-sections, within the uncertainties, do not exceed the value 0.430
(therefore, below the black-disc limit) and the results favor rational limits
between 1/3 and 2/5. We are led to conclude that the rise of the hadronic
cross-sections at the highest energies still constitutes an open problem.


title:
Logical difficulty from combining counterfactuals in the GHZ-Bell
  theorems

abstract:
  In eliminating the fair sampling assumption, the Greenberger, Horne,
Zeilinger (GHZ) theorem is believed to confirm Bell's historic conclusion that
local hidden variables are inconsistent with the results of quantum mechanics.
The GHZ theorem depends on predicting the results of sets of measurements of
which only one may be performed. In the present paper, the non-commutative
aspects of these unperformed measurements are critically examined. Classical
examples and the logic of the GHZ construction are analyzed to demonstrate that
combined counterfactual results of non-commuting operations are in general
logically inconsistent with performed measurement sequences whose results
depend on non-commutation. The Bell theorem is also revisited in the light of
this result. It is concluded that negative conclusions regarding local hidden
variables do not follow from the GHZ and Bell theorems as historically
reasoned.


title:
Unsupervised ensemble of experts (EoE) framework for automatic
  binarization of document images

abstract:
  In recent years, a large number of binarization methods have been developed,
with varying performance generalization and strength against different
benchmarks. In this work, to leverage on these methods, an ensemble of experts
(EoE) framework is introduced, to efficiently combine the outputs of various
methods. The proposed framework offers a new selection process of the
binarization methods, which are actually the experts in the ensemble, by
introducing three concepts: confidentness, endorsement and schools of experts.
The framework, which is highly objective, is built based on two general
principles: (i) consolidation of saturated opinions and (ii) identification of
schools of experts. After building the endorsement graph of the ensemble for an
input document image based on the confidentness of the experts, the saturated
opinions are consolidated, and then the schools of experts are identified by
thresholding the consolidated endorsement graph. A variation of the framework,
in which no selection is made, is also introduced that combines the outputs of
all experts using endorsement-dependent weights. The EoE framework is evaluated
on the set of participating methods in the H-DIBCO'12 contest and also on an
ensemble generated from various instances of grid-based Sauvola method with
promising performance.


title: The Nature of Subproton Scale Turbulence in the Solar Wind

abstract:
  The nature of subproton scale fluctuations in the solar wind is an open
question, partly because two similar types of electromagnetic turbulence can
occur: kinetic Alfven turbulence and whistler turbulence. These two
possibilities, however, have one key qualitative difference: whistler
turbulence, unlike kinetic Alfven turbulence, has negligible power in density
fluctuations. In this Letter, we present new observational data, as well as
analytical and numerical results, to investigate this difference. The results
show, for the first time, that the fluctuations well below the proton scale are
predominantly kinetic Alfven turbulence, and, if present at all, the whistler
fluctuations make up only a small fraction of the total energy.


title:
Magnetic dipole moment of neutral particles from quantum corrections at
  two-loop order

abstract:
  The tentative gamma-ray line in the Fermi data at ~135 GeV motivates a dark
matter candidate that couples to photons through loops of charged messengers.
It was recently shown that this model can explain the observed line, but
achieving the correct phenomenology requires a fairly sizable coupling between
the WIMP and the charged messengers. While strong coupling by itself is not a
problem, it is natural to wonder whether the phenomenological success is not
spoiled by higher order quantum corrections. In this work we compute the
dominant two-loop contributions to the electromagnetic form-factors of the WIMP
and show that over a large portion of the relevant parameter space these
corrections are under control and the phenomenology is not adversely affected.
We also discuss more generally the effects of these form-factors on signals in
direct-detection experiments as well as on the production of the WIMP candidate
in colliders. In particular, for low masses of the charged messengers the
production rate at the LHC enjoys an enhancement from the threshold singularity
associated with these charged states.


title:
Finite Volume Modeling of Poroelastic-Fluid Wave Propagation with Mapped
  Grids

abstract:
  In this work we develop a high-resolution mapped-grid finite volume method
code to model wave propagation in two dimensions in systems of multiple
orthotropic poroelastic media and/or fluids, with curved interfaces between
different media. We use a unified formulation to simplify modeling of the
various interface conditions -- open pores, imperfect hydraulic contact, or
sealed pores -- that may exist between such media. Our numerical code is based
on the Clawpack framework, but in order to obtain correct results at a material
interface we use a modified transverse Riemann solution scheme, and at such
interfaces are forced to drop the second-order correction term typical of
high-resolution finite volume methods. We verify our code against analytical
solutions for reflection and transmission of waves at a material interface, and
for scattering of an acoustic wave train around an isotropic poroelastic
cylinder. For reflection and transmission at a flat interface, we achieve
second-order convergence in the 1-norm, and first-order in the max-norm; for
the cylindrical scatterer, the highly distorted grid mapping degrades
performance but we still achieve convergence at a reduced rate. We also
simulate an acoustic pulse striking a simplified model of a human femur bone,
as an example of the capabilities of the code. To aid in reproducibility, at
the web site http://dx.doi.org/10.6084/m9.figshare.701483 we provide all of the
code used to generate the results here.


title:
Numerical simulations of the possible origin of the two sub-parsec scale
  and counter-rotating stellar disks around SgrA*

abstract:
  We present a high resolution simulation of an idealized model to explain the
origin of the two young, counter-rotating, sub-parsec scale stellar disks
around the supermassive black hole SgrA* at the Center of the Milky Way. In our
model, the collision of a single molecular cloud with a circum-nuclear gas disk
(similar to the one observed presently) leads to multiple streams of gas
flowing towards the black hole and creating accretion disks with angular
momentum depending on the ratio of cloud and circum-nuclear disk material. The
infalling gas creates two inclined, counter-rotating sub-parsec scale accretion
disks around the supermassive black hole with the first disk forming roughly 1
Myr earlier, allowing it to fragment into stars and get dispersed before the
second, counter-rotating disk forms. Fragmentation of the second disk would
lead to the two inclined, counter-rotating stellar disks which are observed at
the Galactic Center. A similar event might be happening again right now at the
Milky Way Galactic Center. Our model predicts that the collision event
generates spiral-like filaments of gas, feeding the Galactic Center prior to
disk formation with a geometry and inflow pattern that is in agreement with the
structure of the so called mini-spiral that has been detected in the Galactic
Center.


title: The Dynamics of Hybrid Metabolic-Genetic Oscillators

abstract:
  The synthetic construction of intracellular circuits is frequently hindered
by a poor knowledge of appropriate kinetics and precise rate parameters. Here,
we use generalized modeling (GM) to study the dynamical behavior of topological
models of a family of hybrid metabolic-genetic circuits known as
"metabolators." Under mild assumptions on the kinetics, we use GM to
analytically prove that all explicit kinetic models which are topologically
analogous to one such circuit, the "core metabolator," cannot undergo Hopf
bifurcations. Then, we examine more detailed models of the metabolator.
Inspired by the experimental observation of a Hopf bifurcation in a
synthetically constructed circuit related to the core metabolator, we apply GM
to identify the critical components of the synthetically constructed
metabolator which must be reintroduced in order to recover the Hopf
bifurcation. Next, we study the dynamics of a re-wired version of the core
metabolator, dubbed the "reverse" metabolator, and show that it exhibits a
substantially richer set of dynamical behaviors, including both local and
global oscillations. Prompted by the observation of relaxation oscillations in
the reverse metabolator, we study the role that a separation of genetic and
metabolic time scales may play in its dynamics, and find that widely separated
time scales promote stability in the circuit. Our results illustrate a generic
pipeline for vetting the potential success of a potential circuit design,
simply by studying the dynamics of the corresponding generalized model.


title: Multiple solutions for the fermion mass function in QED3

abstract:
  Theories that support dynamical generation of a fermion mass gap are of
widespread interest. The phenomenon is often studied via the Dyson-Schwinger
equation (DSE) for the fermion self energy; i.e., the gap equation. When the
rainbow truncation of that equation supports dynamical mass generation, it
typically also possesses a countable infinity of simultaneous solutions for the
dressed-fermion mass function, solutions which may be ordered by the number of
zeros they exhibit. These features can be understood via the theory of
nonlinear Hammerstein integral equations. Using QED3 as an example, we
demonstrate the existence of a large class of gap equation truncations that
possess solutions with damped oscillations. We suggest that there is a larger
class, quite probably including the exact theory, which does not. The structure
of the dressed-fermion--gauge-boson vertex is an important factor in deciding
the issue.

categories: nucl-th cond-mat.supr-con hep-lat hep-ph


title: Mathematical structure of three - dimensional (3D) Ising model

abstract:
  An overview of the mathematical structure of the three-dimensional (3D) Ising
model is given, from the viewpoints of topologic, algebraic and geometric
aspects. By analyzing the relations among transfer matrices of the 3D Ising
model, Reidemeister moves in the knot theory, Yang-Baxter and tetrahedron
equations, the following facts are illustrated for the 3D Ising model: 1) The
complexified quaternion basis constructed for the 3D Ising model represents
naturally the rotation in a (3 + 1) - dimensional space-time, as a relativistic
quantum statistical mechanics model, which is consistent with the 4-fold
integrand of the partition function by taking the time average. 2) A unitary
transformation with a matrix being a spin representation in 2^(nlo)-space
corresponds to a rotation in 2nlo-space, which serves to smooth all the
crossings in the transfer matrices and contributes as the non-trivial topologic
part of the partition function of the 3D Ising model. 3) A tetrahedron relation
would ensure the commutativity of the transfer matrices and the integrability
of the 3D Ising model, and its existence is guaranteed also by the Jordan
algebra and the Jordan-von Neumann-Wigner procedures. 4) The unitary
transformation for smoothing the crossings in the transfer matrices changes the
wave functions by complex phases {\Phi}x, {\Phi}y, and {\Phi}z. The relation
with quantum field and gauge theories, physical significance of weight factors
are discussed in details. The conjectured exact solution is compared with
numerical results, and singularities at/near infinite temperature are
inspected. The analyticity in {\beta} = 1/(kB T) of both the hard-core and
Ising models has been proved for {\beta} > 0, not for {\beta} = 0. Thus the
high-temperature series cannot serve as a standard for judging a putative exact
solution of the 3D Ising model.


title: Spatial Depth-Based Classification for Functional Data

abstract:
  We enlarge the number of available functional depths by introducing the
kernelized functional spatial depth (KFSD). KFSD is a local-oriented and
kernel-based version of the recently proposed functional spatial depth (FSD)
that may be useful for studying functional samples that require an analysis at
a local level. In addition, we consider supervised functional classification
problems, focusing on cases in which the differences between groups are not
extremely clear-cut or the data may contain outlying curves. We perform
classification by means of some available robust methods that involve the use
of a given functional depth, including FSD and KFSD, among others. We use the
functional \textit{k}-nearest neighbor classifier as a benchmark procedure. The
results of a simulation study indicate that the KFSD-based classification
approach leads to good results. Finally, we consider two real classification
problems, obtaining results that are consistent with the findings observed with
simulated curves.


title:
Hot versus Cold: the Dichotomy in Spherical Accretion of Cooling Flows
  onto Supermassive Black Holes in Elliptical Galaxies, Galaxy Groups and
  Clusters

abstract:
  Feedback heating from active galactic nuclei (AGNs) has been commonly invoked
to suppress cooling flows predicted in hot gas in elliptical galaxies, galaxy
groups and clusters. Previous studies have focused on if and how AGN feedback
heats the gas, but little paid attention to its triggering mechanism. Using
spherically symmetric simulations, we investigate how large-scale cooling flows
are accreted by central supermassive black holes (SMBHs) in eight well-observed
systems and find an interesting dichotomy. In massive clusters, the gas
develops a central cooling catastrophe within about the cooling time (typically
~ 100 - 300 Myr), resulting in a cold-mode accretion onto SMBHs. However, in
our four simulated systems on group and galaxy scales at a low metallicity
Z=0.3Z_{sun}, the gas quickly settles into a long-term state which has a cuspy
central temperature profile extending to several tens to about 100 pc. At the
more realistic solar metallicity, two groups (with R_{e} ~ 4 kpc) still host
the long-term hot-mode accretion. Both accretion modes naturally appear in our
idealized calculations where only cooling, gas inflow, and compressional
heating are considered. The long-term hot-mode accretion is maintained by the
quickly-established closeness between the timescales of these processes,
preferably in systems with low gas densities, low gas metallicities, and
importantly, compact central galaxies, which result in strong gravitational
acceleration and compressional heating at the intermediate radii. Our
calculations predict that central cuspy temperature profiles appear more often
in smaller systems than galaxy clusters, which instead often host significant
cold gas and star formation.


title:
Automatic Speech Recognition Using Template Model for Man-Machine
  Interface

abstract:
  Speech is a natural form of communication for human beings, and computers
with the ability to understand speech and speak with a human voice are expected
to contribute to the development of more natural man-machine interfaces.
Computers with this kind of ability are gradually becoming a reality, through
the evolution of speech recognition technologies. Speech is being an important
mode of interaction with computers. In this paper Feature extraction is
implemented using well-known Mel-Frequency Cepstral Coefficients (MFCC).Pattern
matching is done using Dynamic time warping (DTW) algorithm.


title: Connecting Curves in Higher Dimensions

abstract:
  Connecting curves have been shown to organize the rotational structure of
strange attractors in three-dimensional dynamical systems. We extend the
description of connecting curves and their properties to higher dimensions
within the special class of differential dynamical systems. The general
properties of connecting curves are derived and selection rules stated.
Examples are presented to illustrate these properties for dynamical systems of
dimension n=3,4,5.


title: co-Semi-analytic functors

abstract:
  We characterize the category of co-semi-analytic functors and describe an
action of semi-analytic functors on co-semi-analytic functors.


title:
Dualities from large N orbifold equivalence in Chern-Simons-matter
  theories with flavor

abstract:
  We study large N orbifold equivalences involving three-dimensional N=3 and
N=4 supersymmetric quiver Chern-Simons-matter theories. The gravity dual of the
N=3 Chern-Simons-matter theory is described by AdS4xM7 where the tri-Sasaki
manifold M7 is known as the Eschenburg space. We find evidence that a large N
orbifold equivalence for the N=4 case continues from the M-theory limit to the
weak-coupling limit. For the N=3 case, we find consistent large N equivalences
involving a projection changing the nodes of the gauge groups, and also for a
projection changing Chern-Simons levels where for the latter projection, the
BPS monopole operators behave as expected in large N equivalence. For both
cases we show, using the gravity dual, that the critical temperature of the
confinement/deconfinement transition does not change and the entropy behaves as
expected under the orbifold equivalence. We show that large N orbifold
equivalence changing Chern-Simons levels can be explained using the planar
equivalence in the mirror dual.


title:
Testing general relativity using gravitational waves from binary neutron
  stars: Effect of spins

abstract:
  We present a Bayesian data analysis pipeline for testing GR using
gravitational wave signals from coalescing compact binaries, and in particular
binary neutron stars. In this study, we investigate its performance when
sources with spins are taken into account.


title: On the origin of the warm-hot absorbers in the Milky Way's halo

abstract:
  Disc galaxies like the Milky Way are expected to be surrounded by massive
coronae of hot plasma that may contain a significant fraction of the so-called
missing baryons. We investigate whether the local (|vLSR|<400 km/s) warm-hot
absorption features observed towards extra-Galactic sources or halo stars are
consistent with being produced by the cooling of the Milky Way's corona. In our
scheme, cooling occurs at the interface between the disc and the corona and it
is triggered by positive supernova feedback. We combine hydrodynamical
simulations with a dynamical 3D model of the galactic fountain to predict the
all-sky distribution of this cooling material, and we compare it with the
observed distribution of detections for different `warm' (SiIII, SiIV, CII,
CIV) and `hot' (OVI) ionised species. The model reproduces the
position-velocity distribution and the column densities of the vast majority of
warm absorbers and about half of OVI absorbers. We conclude that the warm-hot
gas responsible for most of the detections lies within a few kiloparsecs from
the Galactic plane, where high-metallicity material from the disc mixes
efficiently with the hot corona. This process provides an accretion of a few
Mo/yr of fresh gas that can easily feed the star formation in the disc of the
Galaxy. The remaining OVI detections are likely to be a different population of
absorbers, located in the outskirts of the Galactic corona and/or in the
circumgalactic medium of nearby galaxies.


title:
Spins and Magnetic Moments of $^{49}$K and $^{51}$K: establishing the
  1/2$^+$ and 3/2$^+$ level ordering beyond $N$ = 28

abstract:
  The ground-state spins and magnetic moments of $^{49,51}$K have been measured
using bunched-beam high-resolution collinear laser spectroscopy at ISOLDE-CERN.
For $^{49}$K a ground-state spin $I = 1/2$ was firmly established. The observed
hyperfine structure of $^{51}$K requires a spin $I > 1/2$ and from its magnetic
moment $\mu(^{51}\text{K})= +0.5129(22)\, \mu_N$ a spin/parity $I^\pi=3/2^+$
with a dominant $\pi 1d_{3/2}^{-1}$ hole configuration was deduced. This
establishes for the first time the re-inversion of the single-particle levels
and illustrates the prominent role of the residual monopole interaction for
single-particle levels and shell evolution.


title:
Increasing the Network life Time by Simulated Annealing Algorithm in WSN
  with Point Coverage

abstract:
  Since we are not able to replace the battery in a wireless sensor networks
(WSNs), the issues of energy and lifetime are the most important parameters. In
asymmetrical networks, different sensors with various abilities are used. Super
nodes, with higher power and wider range of communication in comparison with
common sensors, are used to cause connectivity and transmit data to base
stations in these networks. It is crucial to select the parameters of fit
function and monitoring sensors optimally in a point covering network. In this
paper, we utilized an algorithm to select monitoring sensors. The selection is
done by using a novel algorithm that used by simulated annealing. This
selection takes remained energy into consideration. This method increases
lifetime, decreases and balances energy consumption as confirmed by simulation
results.


title: Guaranteed convergence of the Kohn-Sham equations

abstract:
  A sufficiently damped iteration of the Kohn-Sham equations with the exact
functional is proven to always converge to the true ground-state density,
regardless of the initial density or the strength of electron correlation, for
finite Coulomb systems. We numerically implement the exact functional for
one-dimensional continuum systems and demonstrate convergence of the damped KS
algorithm. More strongly correlated systems converge more slowly.


title:
A note on the area and coarea formulas for general volume densities and
  some applications

abstract:
  We present the area and coarea formulas for Lipschitz maps, valid for general
volume densities. As applications, we give a short, "euclidean" proof of the
anisotropic Sobolev inequality and describe an anisotropic tube formula for
hypersurfaces in $mathbb{R}^n$. A discussion about the first variation of the
anisotropic area is also included.


title:
Deconfinement and chiral restoration in nonlocal SU(3) chiral quark
  models

abstract:
  We study the features of nonlocal SU(3) chiral quark models with wave
function renormalization. Model parameters are determined from meson
phenomenology, considering different nonlocal form factor shapes. In this
context we analyze the characteristics of the deconfinement and chiral
restoration transitions at finite temperature, introducing the couplings of
fermions to the Polyakov loop. We analyze the results obtained for various
thermodynamical quantities considering different Polyakov loop potentials and
nonlocal form factors, in comparison with data obtained from lattice QCD
calculations.


title: Linear Optimization with Cones of Moments and Nonnegative Polynomials

abstract:
  Let A be a finite subset of N^n and R[x]_A be the space of real polynomials
whose monomial powers are from A. Let K be a compact basic semialgebraic set of
R^n such that R[x]_A contains a polynomial that is positive on K. Denote by
P_A(K) the cone of polynomials in R[x]_A that are nonnegative on K. The dual
cone of P_A(K) is R_A(K), the set of all A-truncated moment sequences in R^A
that admit representing measures supported in K. Our main results are: i) We
study the properties of P_A(K) and R_A(K) (like interiors, closeness, duality,
memberships), and construct a convergent hierarchy of semidefinite relaxations
for each of them. ii) We propose a semidefinite algorithm for solving linear
optimization problems with the cones P_A(K) and R_A(K), and prove its
asymptotic and finite convergence; a stopping criterion is also given. iii) We
show how to check whether P_A(K) and R_A(K) intersect affine subspaces; if they
do, we show to get get a point in the intersections; if they do not, we prove
certificates for the non-intersecting.


title:
Long-range correlations in proton-lead collisions at sqrt{s_NN} = 5.02
  TeV from ATLAS

abstract:
  Two-particle correlations in relative azimuth $\Delta\phi$ and relative
pseudorapidity $\Delta\eta$ are studied in p+Pb collisions at sqrt{s_NN}=5.02
TeV with the ATLAS detector at LHC. The correlations are studied as a function
of charged particle pT and the collision E_T^fcal summed over 3.1 < eta < 4.9
in the direction of the Pb beam. After subtracting the known sources of
correlations such as dijets, resonances and momentum conservation, estimated
using events with low E_T^fcal, the resulting correlations exhibit a
$\Delta\phi$ modulation that is flat in $\Delta\eta$ out to $|\Delta\eta|=5$.
The modulation is comparable in magnitude to similar modulations observed in
heavy ion collisions, and can be described by a
$1+2c_2\cos2\Delta\phi+2c_3\cos3\Delta\phi$ function over 0.5<pT<7 GeV in broad
ranges of E_T^fcal. The correlation analysis is repeated for event classes
defined by the number of reconstructed charged particles N_ch^rec. This
analysis gives nearly the same result as the analysis based on E_T^fcal for the
long-range correlation at the near-side ($\Delta\phi~0$), but leads to biases
in the long-range correlations at the away-side ($\Delta\phi\sim\pi$). HIJING
simulation suggests that this bias is mainly associated with the contributions
from dijets which are correlated strongly with the N_ch^rec.


title: Discrete time q-TASEPs

abstract:
  We introduce two new exactly solvable (stochastic) interacting particle
systems which are discrete time versions of q-TASEP. We call these geometric
and Bernoulli discrete time q-TASEP. We obtain concise formulas for
expectations of a large enough class of observables of the systems to
completely characterize their fixed time distributions when started from step
initial condition. We then extract Fredholm determinant formulas for the
marginal distribution of the location of any given particle.
  Underlying this work is the fact that these expectations solve closed systems
of difference equations which can be rewritten as free evolution equations with
k-1 two-body boundary conditions -- discrete q-deformed versions of the quantum
delta Bose gas. These can be solved via a nested contour integral ansatz. The
same solutions also arise in the study of Macdonald processes, and we show how
the systems of equations our expectations solve are equivalent to certain
commutation relations involving the Macdonald first difference operator.

categories: math.PR cond-mat.stat-mech math-ph math.MP


title: Braiding link cobordisms and non-ribbon surfaces

abstract:
  We define the notion of a braided link cobordism in $S^3 \times [0,1]$, which
generalizes Viro's closed surface braids in $\mathbb{R}^4$. We prove that any
properly embedded oriented surface $W \subset S^3 \times [0,1]$ is isotopic to
a surface in this special position, and that the isotopy can be taken rel
boundary when $\partial W$ already consists of closed braids. These surfaces
are closely related to another notion of surface braiding in $D^2 \times D^2$,
called braided surfaces with caps, which are a generalization of Rudolph's
braided surfaces. We mention several applications of braided surfaces with
caps, including using them to apply algebraic techniques from braid groups to
studying surfaces in 4-space, as well as constructing singular fibrations on
smooth 4-manifolds from a given handle decomposition.


title:
Blind Adaptive Reduced-Rank Detectors for DS-UWB Systems Based on Joint
  Iterative Optimization and the Constrained Constant Modulus Criterion

abstract:
  A novel linear blind adaptive receiver based on joint iterative optimization
(JIO) and the constrained constant modulus (CCM) design criterion is proposed
for interference suppression in direct-sequence ultra-wideband (DS-UWB)
systems. The proposed blind receiver consists of two parts, a transformation
matrix that performs dimensionality reduction and a reduced-rank filter that
produces the output. In the proposed receiver, the transformation matrix and
the reduced-rank filter are updated jointly and iteratively to minimize the
constant modulus (CM) cost function subject to a constraint. Adaptive
implementations for the JIO receiver are developed by using the normalized
stochastic gradient (NSG) and recursive least-squares (RLS) algorithms. In
order to obtain a low-complexity scheme, the columns of the transformation
matrix with the RLS algorithm are updated individually. Blind channel
estimation algorithms for both versions (NSG and RLS) are implemented. Assuming
the perfect timing, the JIO receiver only requires the spreading code of the
desired user and the received data. Simulation results show that both versions
of the proposed JIO receivers have excellent performance in suppressing the
inter-symbol interference (ISI) and multiple access interference (MAI) with a
low complexity.


title:
SU(3) deconfining phase transition with finite volume corrections due to
  a confined exterior

abstract:
  Using the geometry of a double-layered torus we investigate the deconfining
phase transition of pure SU(3) lattice gauge theory by Markov chain Monte Carlo
simulations. In one layer, called "outside", the temperature is set below the
deconfining temperature and in the other, called "inside", it is iterated to a
pseudo-transition temperature. Lattice sizes are chosen in a range suggested by
the physical volumes achieved in relativistic heavy ion collisions and both
temperatures are kept close enough to stay in the SU(3) scaling region.
Properties of the transition are studied as function of the volume for three
outside temperatures. When compared with infinite volume extrapolations, small
volume corrections of the deconfining temperature and width become competitive
with those found by including quarks. Effective finite size scaling exponents
of the specific and Polyakov loop susceptibilities are also calculated.


title:
General Rule Predicting the Hidden Induced Order Parameters and the
  Formation of Quartets and Patterns of Condensates

abstract:
  We reveal the rule with which we predicted, and verified by detailed
numerical calculations on dozens of specific cases over the last decade, the
emergence of hidden induced states and the formation of quartets of order
parameters. The rule stipulates that if N order parameters are such that their
cyclic products equal +1 or -1 then the presence of any N-1 of them will
necessarily induce the missing order parameter as a hidden order. We
demonstrate that the rule results from general microscopic mean field theory
and is thus universally valid. Of exceptional physical interest are the cases
N=4 called quartets, and all N>4 cases decompose into overlaping quartets which
are the building blocks of observable patterns of condensates. Quartets may be
found in two regimes, the "hierarchy" regime and the "equity" regime, and
transitions between the two regimes exhibit universal characteristics.
Following the rule, we predict many characteristic examples of quartets
involving all types of particle-hole and superconducting condensates.


title: Hyperbolicity and Types of Shadowing for C1 Generic Vector Fields

abstract:
  We study various types of shadowing properties and their implication for C1
generic vector fields. We show that, generically, any of the following three
hypotheses implies that an isolated set is topologically transitive and
hyperbolic: (i) the set is chain transitive and satisfies the (classical)
shadowing property, (ii) the set satisfies the limit shadowing property, or
(iii) the set satisfies the (asymptotic) shadowing property with the additional
hypothesis that stable and unstable manifolds of any pair of critical orbits
intersect each other. In our proof we essentially rely on the property of chain
transitivity and, in particular, show that it is implied by the limit shadowing
property. We also apply our results to divergence-free vector fields.


title: Evolution of Cooperation in an Incentive Based Business Game Environment

abstract:
  This paper discusses our investigation into the evolution of cooperative
players in an online business environment. We explain our design of an
incentive based system with its foundation over binary reputation system whose
proportion of reward or punishment is a function of transaction value and the
players past history of cooperation. We compare the evolution of cooperation in
our setting with non-incentive based environment and our findings show that the
incentive based method is more suitable for the evolution of trustworthy
players.


title: Unraveling the Evolution of Defectors in Online Business Games

abstract:
  Anonymous online business environments have a social dilemma situation in it.
A dilemma on whether to cooperate or Defect. Defection by a buyer to seller
and/or seller to buyer might give each a better profit at the cost of the loss
of other. However, if these parties were to interact in future too, a bad past
reference might prevent cooperative actions, thus depriving each other from a
better gain. The anonymity of the players and an absence of central governing
body still make this environment tempting for the defectors. What might be the
evolutionary behavior of defectors in such environment? How could their
increasing population be controlled? It is these two questions basically that
we attempt to address in this research work. A genetic algorithm based spatial
iterated prisoners dilemma (SIPD) environment has been used to simulate the
experiments. A case where compensation for the looser is provided by the system
is modeled and analyzed through experiments. Our results show that compensation
can be useful in decreasing defective population in the society, however, this
might not be enough for the evolution of a cooperative and reliable society of
trustworthy players.


title: A Model for the Dynamics of Gene Networks

abstract:
  In this work we propose a model for gene expression based on the theory of
random dynamical systems (RDS) and show that it has a "modularity property" in
the following sense: given any collection of genes that are linked in a
transcriptional network, if each of them is individually described by a certain
class of RDS then there is a natural, and essentially unique, prescription for
coupling them together, respecting the network topology, in such a way that the
collective system formed by all genes is a RDS as well. Moreover, the class of
RDS used to describe the individual genes is flexible enough to account for a
wide range of stochastic behaviors within the realm of stationary processes.


title: Metrics for Computing Trust in a Multi-Agent Environment

abstract:
  One of the risks involved in multi agent community is in the identification
of trustworthy agent partners for transaction. In this paper we aim to describe
a trust model for measuring trust in the interacting agents. The trust metric
model works on the basis of the parameters that we have identified. The model
primarily analyses trust value on the basis of the agents reputation, as
provided by the agent itself, and the agents aggregate rating as provided by
the witness agents. The final computation of the trust value is given by a
weighted average of these two components. While computing the aggregate rating,
a weight based method has been adopted to discount the contribution of possibly
unfair ratings by the witness agents.


title: Estimating or Propagating Gradients Through Stochastic Neurons

abstract:
  Stochastic neurons can be useful for a number of reasons in deep learning
models, but in many cases they pose a challenging problem: how to estimate the
gradient of a loss function with respect to the input of such stochastic
neurons, i.e., can we "back-propagate" through these stochastic neurons? We
examine this question, existing approaches, and present two novel families of
solutions, applicable in different settings. In particular, it is demonstrated
that a simple biologically plausible formula gives rise to an an unbiased (but
noisy) estimator of the gradient with respect to a binary stochastic neuron
firing probability. Unlike other estimators which view the noise as a small
perturbation in order to estimate gradients by finite differences, this
estimator is unbiased even without assuming that the stochastic perturbation is
small. This estimator is also interesting because it can be applied in very
general settings which do not allow gradient back-propagation, including the
estimation of the gradient with respect to future rewards, as required in
reinforcement learning setups. We also propose an approach to approximating
this unbiased but high-variance estimator by learning to predict it using a
biased estimator. The second approach we propose assumes that an estimator of
the gradient can be back-propagated and it provides an unbiased estimator of
the gradient, but can only work with non-linearities unlike the hard threshold,
but like the rectifier, that are not flat for all of their range. This is
similar to traditional sigmoidal units but has the advantage that for many
inputs, a hard decision (e.g., a 0 output) can be produced, which would be
convenient for conditional computation and achieving sparse representations and
sparse gradients.


title: Open book decompositions of $\mathbb{S}^{5}$ and real singularities

abstract:
  In this article, we study the topology of the family of real analytic germs
$F \colon (\mathbb{C}^3,0) \to (\mathbb{C},0)$ given by
$F(x,y,z)=\bar{xy}(x^p+y^q)+z^r$ with $p,q,r \in \mathbb{N}$, $p,q,r \geq 2$
and $(p,q)=1$. Such a germ has isolated singularity at 0 and gives rise to a
Milnor fibration $\frac{F}{|F|} \colon \mathbb{S}^{5} \setminus L_F \to
\mathbb{S}^{1}$. We describe the link $L_F$ as a Seifert manifold and we show
that it is always homeomorphic to the link of a complex singularity. However,
we prove that in almost all the cases the open-book decomposition of
$\mathbb{S}^{5}$ given by the Milnor fibration of $F$ cannot come from the
Milnor fibration of a complex singularity in $\mathbb{C}^3$.


title:
On the Full Spectrum Fitting of Luminous Red Galaxies by Using ULySS and
  STARLIGHT

abstract:
  In this paper, we select a sample of quiescent luminous red galaxies (LRGs)
from Sloan Digital Sky Survey Data Release 7 (SDSS DR7) with signal-to-noise
ratio (S/N) substantially high to study the consistency of the full spectrum
fitting method by using different packages, mainly, ULySS and STARLIGHT. The
spectrum of each galaxy in the sample is fitted by the full spectrum fitting
packages ULySS and STARLIGHT, respectively. We find: (1) for spectra with
higher S/Ns, the ages of stellar populations obtained from ULySS are slightly
older than that from STARLIGHT, and metallicities derived from ULySS are
slightly richer than that from STARLIGHT. In general, both packages can give
roughly consistent fitting results. (2) for low S/N spectra, it is possible
that the fitting by ULySS can be trapped some local minimum parametric regions
during execution and thus may give unreliable results, while STARLIGHT can
still give reliable results. Based on the fitting results of LRGs, we further
analyse their star formation history (SFH) and the relation between their age
and velocity dispersion, and find that those highly agrees with conclusions
from others' previous work.


title: Opportunistic Interference Management for Multicarrier systems

abstract:
  We study opportunistic interference management when there is bursty
interference in parallel 2-user linear deterministic interference channels. A
degraded message set communication problem is formulated to exploit the
burstiness of interference in M subcarriers allocated to each user. We focus on
symmetric rate requirements based on the number of interfered subcarriers
rather than the exact set of interfered subcarriers. Inner bounds are obtained
using erasure coding, signal-scale alignment and Han-Kobayashi coding strategy.
Tight outer bounds for a variety of regimes are obtained using the El
Gamal-Costa injective interference channel bounds and a sliding window subset
entropy inequality. The result demonstrates an application of techniques from
multilevel diversity coding to interference channels. We also conjecture outer
bounds indicating the sub-optimality of erasure coding across subcarriers in
certain regimes.


title: Judicious partitions of directed graphs

abstract:
  The area of judicious partitioning considers the general family of
partitioning problems in which one seeks to optimize several parameters
simultaneously, and these problems have been widely studied in various
combinatorial contexts. In this paper, we study essentially the most
fundamental judicious partitioning problem for directed graphs, which naturally
extends the classical Max Cut problem to this setting: we seek bipartitions in
which many edges cross in each direction. It is easy to see that a minimum
outdegree condition is required in order for the problem to be nontrivial, and
we prove that every directed graph with M edges and minimum outdegree at least
two admits a bipartition in which at least (1/6 + o(1))M edges cross in each
direction. We also prove that if the minimum outdegree is at least three, then
the constant can be increased to 1/5. If the minimum outdegree tends to
infinity with N, then the constant increases to 1/4. All of these constants are
best-possible, and provide asymptotic answers to a question of Alex Scott.


title:
Global well-posedness and symmetries for dissipative active scalar
  equations with positive-order couplings

abstract:
  We consider a family of dissipative active scalar equations outside the
$L^{2}$-space. This was introduced in [D. Chae, P. Constantin, J. Wu, to appear
in IUMJ (2014)] and its velocity fields are coupled with the active scalar via
a class of multiplier operators which morally behave as derivatives of positive
order. We prove global well-posedness and time decay of solutions, without
smallness assumptions, for initial data belonging to the critical Lebesgue
space $L^{\frac{n}{\gamma-\beta}}(\mathbb{R}^{n})$ which is a class larger than
that of the above reference. Symmetry properties of solutions are investigated
depending on the symmetry of initial data and coupling operators.


title: 125 GeV Higgs bosons in two-Higgs-doublet models

abstract:
  Moriond 2013 ALTAS data at 125 GeV state appears to exhibit a substantial
excess in the di-photon final state and in the ZZ decaying to four lepton
channel, whereas which are more or less SM-like rate observed by CMS MVA
analysis. We examine the maximum Higgs signal enhancements that can be achieved
in the 2HDM when either a single Higgs or more than one Higgs have mass(es)
near 125 GeV. In general, the constraints of vacuum stability, unitarity and
perturbativity play the key role in restricting possibilities of signal
enhancement. The Type II model allows for an enhancement in the di-photon rate
(relative to the SM) of the order of 2-3 but associated with an even larger ZZ
or too large \tau\tau signal. In contrast, the maximal value of the di-photon
signal in the Type I model can reach the order of 1.3 for which the ZZ signal
is of order 1.


title: Symplectic capacities from Hamiltonian circle actions

abstract:
  Let $M$ be a closed Fano symplectic manifold with a semifree Hamiltonian
circle action with isolated maximum. We compute the Gromov width and the
Hofer-Zehnder capacity of $M$ using a moment map.


title: Generalized Strichartz estimates and scattering for 3D Zakharov system

abstract:
  We obtain scattering for the 3D Zakharov system with non-radial small data in
the energy space with angular regularity of degree one. The main ingredient is
a generalized Strichartz estimate for the Schr\"odinger equation in the space
of $L^2$ angular integrability.


title: Challenges of Relativistic Astrophysics

abstract:
  I discuss some of the most outstanding challenges in relativistic
astrophysics in the subjects of: compact objects (Black Holes and Neutron
Stars); dark sector (Dark Matter and Dark Energy); plasma astrophysics (Origin
of Jets, Cosmic Rays and Magnetic Fields) and the primordial universe (Physics
at the beginning of the Universe). In these four subjects, I discuss twelve of
the most important challenges. These challenges give us insight into new
physics that can only be studied in the large scale Universe. The near future
possibilities, in observations and theory, for addressing these challenges, are
also discussed.


title:
Batalin-Vilkovisky algebra structures on (Co)Tor and Poisson
  bialgebroids

abstract:
  In this article, we extend our preceding studies on higher algebraic
structures of (co)homology theories defined by a left bialgebroid (U,A). For a
braided commutative Yetter-Drinfel'd algebra N, explicit expressions for the
canonical Gerstenhaber algebra structure on Ext_U(A,N) are given. Similarly, if
(U,A) is a left Hopf algebroid where A is an anti Yetter-Drinfel'd module over
U, it is shown that the cochain complex computing Cotor_U(A,N) defines a cyclic
operad with multiplication and hence the groups Cotor_U(A,N) form a
Batalin-Vilkovisky algebra. In the second part of this article, Poisson
structures and the Poisson bicomplex for bialgebroids are introduced, which
simultaneously generalise, for example, classical Poisson as well as cyclic
homology. In case the bialgebroid U is commutative, a Poisson structure on U
leads to a Batalin-Vilkovisky algebra structure on Tor_U(A,A). As an
illustration, we show how this generalises the classical Koszul bracket on
differential forms, and conclude by indicating how classical Lie-Rinehart
bialgebras (or, geometrically, Lie bialgebroids) arise from left bialgebroids.


title:
Spin-polarized bandgap of graphene induced by alternative chemisorption
  with MgO (111) substrate

abstract:
  Using First-principle calculations, substrate effect of O-terminated (rt3 x
rt3) MgO (111) on graphene was investigated for spintronics application.
Surprisingly, the graphene can be turned into a spin-polarized semiconductor,
which implies that the totally spin-polarized current can be generated and its
on/off switching can be also controlled. The origin of the spin-polarized band
structure is spin-ordering due to alternative sp2-sp3 covalent bondings induced
by the MgO (111) substrate. The results indicate that the tailored pattern of
the chemisorption can be highly efficient or introducing totally spin-polarized
current to the graphene.


title: Higher dimensional divergence for mapping class groups

abstract:
  In this paper we investigate the higher dimensional divergence functions of
mapping class groups of surfaces and of CAT(0)--groups. We show that, for
mapping class groups of surfaces, these functions exhibit phase transitions at
the rank (as measured by thrice the genus plus the number of punctures minus
3). We also provide inductive constructions of CAT(0)--spaces with co-compact
group actions, for which the divergence below the rank is (exactly) a
polynomial function of our choice, with degree arbitrarily large compared to
the dimension.


title:
Effect of electron-phonon interactions on orbital fluctuations in
  iron-based superconductors

abstract:
  To investigate the possibility whether electron-phonon coupling can enhance
orbital fluctuations in iron-based superconductors, we develop an ab initio
method to construct the effective low-energy models including the
phonon-related terms. With the derived effective electron-phonon interactions
and phonon frequencies, we estimate the static part (\omega=0) of the
phonon-mediated effective on-site intra- or inter-orbital electron-electron
attractions as ~ -0.4 eV and exchange or pair-hopping terms as ~ -0.02 eV. We
analyze the model with the derived interactions together with the electronic
repulsions within the random phase approximation. We find that the enhancement
of the orbital fluctuations due to the electron-phonon interactions is small,
making the spin fluctuations dominant. As a result, the superconducting state
with the sign reversal in gap functions ($s_\pm$-wave) is realized.


title: Note on Construction of Dual-trace Factor in Yang-Mills Theory

abstract:
  In this note we provide a new construction of BCJ dual-trace factor using the
kinematic algebra proposed in arXiv:1105.2565 and arXiv:1212.6168. Different
from the construction given in arXiv:1304.2978 based on the proposal of
arXiv:1103.0312, the method used in this note exploits the adjoint
representation of kinematic algebra and the use of inner product in dual space.
The dual-trace factor defined in this way naturally satisfies cyclic symmetry
condition but not KK-relation, just like the trace of U(N) Lie algebra
satisfies cyclic symmetry condition, but not KK-relation. In other words the
new construction naturally leads to formulation sharing more similarities with
the color decomposition of Yang-Mills amplitude.


title: Missing short-range interactions in the hydrogen bond of compressed ice

abstract:
  Combining the Lagrangian-Laplace mechanics and the known pressure dependence
of the length-stiffness relaxation dynamics, we have determined the critical,
yet often-overlooked, short-range interactions in the hydrogen bond of
compressed ice. This approach has enabled determination of the force constant,
cohesive energy, potential energy of the vdW and the covalent segment at each
quasi-equilibrium state as well as their pressure dependence. Evidencing the
essentiality of the inter-electron-pair Coulomb repulsion and the segmental
strength disparity in determining the asymmetric H-bond relaxation dynamics and
the anomalous properties of ice, results confirmed that compression shortens
and stiffens the OH bond and meanwhile lengthens and softens the covalent bond.


title:
A removal singularity theorem of the Donaldson-Thomas instantons on
  compact K\"ahler threefolds

abstract:
  We consider a perturbed Hermitian-Einstein equation, which we call the
Donaldson-Thomas equation, on compact K\"ahler threefolds. In arXiv:0805.2195,
we analysed some analytic properties of solutions to the equation, in
particular, we proved that a sequence of solutions to the Donaldson-Thomas
equation has a subsequence which smoothly converges to a solution to the
Donaldson-Thomas equation outside a closed subset of the Hausdorff dimension
two. In this article, we prove that some of these singularities can be removed.


title: Dynamic Spectrum Refarming of GSM Spectrum for LTE Small Cells

abstract:
  In this paper we propose a novel solution called dynamic spectrum refarming
(DSR) for deploying LTE small cells using the same spectrum as existing GSM
networks. The basic idea of DSR is that LTE small cells are deployed in the GSM
spectrum but suppress transmission of all signals including the reference
signals in some specific physical resource blocks corresponding to a portion of
the GSM carriers to ensure full GSM coverage. Our study shows that the proposed
solution can provide LTE mobile terminals with high speed data services when
they are in the coverage of the LTE small cells while minimally affecting the
service provided to GSM terminals located within the LTE small cell coverage
area. Thus, the proposal allows the normal operation of the existing GSM
networks even with LTE small cells deployed in that spectrum. Though the focus
of this paper is about GSM spectrum refarming, an analogous approach can be
applied to reuse code division multiple access (CDMA) spectrum for LTE small
cells.


title: Michael-Simon inequalities for $k$-th mean curvatures

abstract:
  This paper continues the study of Alexandrov-Fenchel inequalities for
quermassintegrals for $k$-convex domains. It focuses on the application to the
Michael-Simon type inequalities for $k$-curvature operators. The proof uses
optimal transport maps as a tool to relate curvature quantities defined on the
boundary of a domain.


title: Limits and decomposition of de Bruijn's additive systems

abstract:
  An additive system for the nonnegative integers is a family (A_i)_{i\in I} of
sets of nonnegative integers with 0 \in A_i for all i \in I such that every
nonnegative integer can be written uniquely in the form \sum_{i\in I} a_i with
a_i \in A_i for all i and a_i \neq 0 for only finitely many i. In 1956, de
Bruijn proved that every additive system is constructed from an infinite
sequence (g_i)_{i \in \N} of integers with g_i \geq 2 for all i, or is a
contraction of such a system. This paper gives a complete classification of the
"uncontractable" or "indecomposable" additive systems, and also considers
limits and stability of additive systems.