title:
Simple and Efficient Local Codes for Distributed Stable Network
  Construction

abstract:
  In this work, we study protocols so that populations of distributed processes
can construct networks. In order to highlight the basic principles of
distributed network construction we keep the model minimal in all respects. In
particular, we assume finite-state processes that all begin from the same
initial state and all execute the same protocol (i.e. the system is
homogeneous). Moreover, we assume pairwise interactions between the processes
that are scheduled by an adversary. The only constraint on the adversary
scheduler is that it must be fair. In order to allow processes to construct
networks, we let them activate and deactivate their pairwise connections. When
two processes interact, the protocol takes as input the states of the processes
and the state of the their connection and updates all of them. Initially all
connections are inactive and the goal is for the processes, after interacting
and activating/deactivating connections for a while, to end up with a desired
stable network. We give protocols (optimal in some cases) and lower bounds for
several basic network construction problems such as spanning line, spanning
ring, spanning star, and regular network. We provide proofs of correctness for
all of our protocols and analyze the expected time to convergence of most of
them under a uniform random scheduler that selects the next pair of interacting
processes uniformly at random from all such pairs. Finally, we prove several
universality results by presenting generic protocols that are capable of
simulating a Turing Machine (TM) and exploiting it in order to construct a
large class of networks.


title: The IceCube Neutrino Observatory Part I: Point Source Searches

abstract:
  Papers on point source searches submitted to the 33nd International Cosmic
Ray Conference (Rio de Janeiro 2013) by the IceCube Collaboration.


title: Multiplicative decomposition of arithmetic progressions in prime fields

abstract:
  We prove that there exists an absolute constant $c>0$ such that if an
arithmetic progression $\cP$ modulo a prime number $p$ does not contain zero
and has the cardinality less than $cp$, then it can not be represented as a
product of two subsets of cardinality greater than 1, unless $\cP=-\cP$ or
$\cP=\{-2r,r,4r\}$ for some residue $r$ modulo $p$.


title:
Constrained-DFT method for accurate energy level alignment of
  metal/molecule interfaces

abstract:
  We present a computational scheme for extracting the energy level alignment
of a metal/molecule interface, based on constrained density functional theory
and local exchange and correlation functionals. The method, applied here to
benzene on Li(100), allows us to evaluate charge transfer energies, as well as
the spatial distribution of the image charge induced on the metal surface. We
systematically study the energies for charge transfer from the molecule to the
substrate as function of the molecule-substrate distance, and investigate the
effects arising from image charge confinement and local charge neutrality
violation. For benzene on Li(100) we find that the image charge plane is
located at about 1.8 \AA above the Li surface, and that our calculated charge
transfer energies compare perfectly with those obtained with a classical
electrostatic model having the image plane located at the same position. The
methodology outlined here can be applied to study any metal/organic interface
in the weak coupling limit at the computational cost of a total energy
calculation. Most importantly, as the scheme is based on total energies and not
on correcting the Kohn-Sham quasiparticle spectrum, accurate results can be
obtained with local/semi-local exchange and correlation functionals. This
enables a systematic approach to convergence.


title:
The spherically symmetric Einstein-scalar field system with positive and
  vanishing cosmological constant: a comparison

abstract:
  We review recent results concerning the spherically symmetric Einstein-scalar
field system with positive cosmological constant. We do so by comparing with
the classical results of Christodoulou concerning the asymptotically flat case
(vanishing cosmological constant) and by discussing some of the issues which
have emerged since the publication of our main results. Concerning the positive
cosmological constant case, we also sketch an alternative proof of global in
(Bondi) time existence, based on energy estimates, which is presumably more
flexible and, consequently, amenable to generalizations; other potential
improvements and generalizations of our main results are also discussed.


title: Phase diagrams of magnetopolariton gases

abstract:
  The magnetic field effect on phase transitions in electrically neutral
bosonic systems is much less studied than those in fermionic systems, such as
superconducting or ferromagnetic phase transitions. Nevertheless, composite
bosons are strongly sensitive to magnetic fields: both their internal structure
and motion as whole particles may be affected. A joint effort of ten
laboratories has been focused on studies of polariton lasers, where
non-equilibrium Bose-Einstein condensates of bosonic quasiparticles,
exciton-polaritons, may appear or disappear under an effect of applied magnetic
fields. Polariton lasers based on pillar or planar microcavities were excited
both optically and electrically. In all cases a pronounced dependence of the
onset to lasing on the magnetic field has been observed. For the sake of
comparison, photon lasing (lasing by an electron-hole plasma) in the presence
of a magnetic field has been studied on the same samples as polariton lasing.
The threshold to photon lasing is essentially governed by the excitonic Mott
transition which appears to be sensitive to magnetic fields too. All the
observed experimental features are qualitatively described within a uniform
model based on coupled diffusion equations for electrons, holes and excitons
and the Gross-Pitaevskii equation for exciton-polariton condensates. Our
research sheds more light on the physics of non-equilibrium Bose-Einstein
condensates and the results manifest high potentiality of polariton lasers for
spin-based quantum logic applications.


title:
Pryms of non-cyclic triple coverings and log canonical models of the
  spin moduli space of genus 2

abstract:
  We show that the moduli spaces of non-triple cyclic coverings of genus 2
curves and that of even spin curves of genus 2 are birationally isomorphic via
the Prym map. We describe the log canonical models of the moduli space of even
spin curves of genus 2 and use this to extend the above birational map.


title: Orbital Parameters for the Two Young Binaries VSB 111 and VSB 126

abstract:
  We report orbital parameters for two low-mass, pre-main sequence,
double-lined spectroscopic binaries VSB 111 and VSB 126. These systems were
originally identified as single-lined on the basis of visible-light
observations. We obtained high-resolution, infrared spectra with the 10-m Keck
II telescope, detected absorption lines of the secondary stars, and measured
radial velocities of both components in the systems. The visible light spectra
were obtained on the 1.5-m Wyeth reflector at the Oak Ridge Observatory, the
1.5-m Tillinghast reflector at the F. L. Whipple Observatory, and the 4.5-m
equivalent Multiple Mirror Telescope. The combination of our visible and
infrared observations of VSB 111 leads to a period of 902.1+/-0.9 days, an
eccentricity of 0.788+/-0.008, and a mass ratio of 0.52+/-0.05. VSB 126 has a
period of 12.9244+/-0.0002 days, an eccentricity of 0.18+/-0.02, and a mass
ratio of 0.29+/-0.02. Visible-light photometry, using the 0.8-m telescope at
Lowell Observatory, provided rotation periods for the primary stars in both
systems, 3.74+/-0.02 days for VSB 111 and 5.71+/-0.07 days for VSB 126. Both
binaries are located in the young, active star-forming cluster NGC 2264 at a
distance of ~800 pc. The difference in the center-of-mass velocities of the two
systems is consistent with the radial velocity gradient seen across NGC 2264.
To test the evolutionary models for accuracy and consistency, we compare the
stellar properties derived from several sets of theoretical calculations for
pre-main sequence evolution with our dynamical results.


title:
Inflation, Leptogenesis, and Yukawa Quasi-Unification within a
  Supersymmetric Left-Right Model

abstract:
  A simple extension of the minimal left-right symmetric supersymmetric grand
unified theory model is constructed by adding two pairs of superfields. This
naturally violates the partial Yukawa unification predicted by the minimal
model. After including supergravity corrections, we find that this extended
model naturally supports hilltop F-term hybrid inflation along its trivial
inflationary path with only a very mild tuning of the initial conditions. With
a convenient choice of signs of the terms in the Kahler potential, we can
reconcile the inflationary scale with the supersymmetric grand unified theory
scale. All the current data on the inflationary observables are readily
reproduced. Inflation is followed by non-thermal leptogenesis via the decay of
the right-handed neutrinos emerging from the decay of the inflaton and any
possible washout of the lepton asymmetry is avoided thanks to the violation of
partial Yukawa unification. The extra superfields also assist us in reducing
the reheat temperature so as to satisfy the gravitino constraint. The observed
baryon asymmetry of the universe is naturally reproduced consistently with the
neutrino oscillation parameters.


title: Generalized Sherrington--Kirkpatrick-glass without reflection symmetry

abstract:
  We investigate generalized Sherrington--Kirkpatrick glassy systems without
reflection symmetry. In the neighbourhood of the transition temperature we in
general uncover the structure of the glass state building the
full-replica-symmetry breaking solution. Physical example of explicitly
constructed solution is given.


title: Axion-like Particles from String Compactifications

abstract:
  We review how axion-like particles (ALPs) naturally emerge in the low-energy
effective field theory of string compactifications. We focus on the study of
their mass spectrum and couplings, stressing that they depend on the mechanism
used to fix the moduli. We present concrete examples where either open or
closed string modes behave as QCD axions which do not overproduce cold dark
matter. Relativistic ALPs can also be produced by the decay of the lightest
modulus which drives reheating. These ALPs contribute to dark radiation and
could be detected via axion-photon conversion in astrophysical magnetic fields.


title:
Linear combination of one-step predictive information with an external
  reward in an episodic policy gradient setting: a critical analysis

abstract:
  One of the main challenges in the field of embodied artificial intelligence
is the open-ended autonomous learning of complex behaviours. Our approach is to
use task-independent, information-driven intrinsic motivation(s) to support
task-dependent learning. The work presented here is a preliminary step in which
we investigate the predictive information (the mutual information of the past
and future of the sensor stream) as an intrinsic drive, ideally supporting any
kind of task acquisition. Previous experiments have shown that the predictive
information (PI) is a good candidate to support autonomous, open-ended learning
of complex behaviours, because a maximisation of the PI corresponds to an
exploration of morphology- and environment-dependent behavioural regularities.
The idea is that these regularities can then be exploited in order to solve any
given task. Three different experiments are presented and their results lead to
the conclusion that the linear combination of the one-step PI with an external
reward function is not generally recommended in an episodic policy gradient
setting. Only for hard tasks a great speed-up can be achieved at the cost of an
asymptotic performance lost.


title: Nonlinear waves on the surface of a fluid covered by an elastic sheet

abstract:
  We experimentally study linear and nonlinear waves on the surface of a fluid
covered by an elastic sheet where both tension and flexural waves take place.
An optical method is used to obtain the full space-time wave field, and the
dispersion relation of waves. When the forcing is increased, a significant
nonlinear shift of the dispersion relation is observed. We show that this shift
is due to an additional tension of the sheet induced by the transverse motion
of a fundamental mode of the sheet. When the system is subjected to a random
noise forcing at large scale, a regime of hydro-elastic wave turbulence is
observed with a power-law spectrum of the scale in disagreement with the wave
turbulence prediction. We show that the separation between relevant time scales
is well satisfied at each scale of the turbulent cascade as expected
theoretically. The wave field anisotropy, and finite size effects are also
quantified and are not at the origin of the discrepancy. Finally, the
dissipation is found to occur at all scales of the cascade contrary to the
theoretical hypothesis, and could thus explain this disagreement.

categories: physics.flu-dyn cond-mat.other nlin.CD physics.class-ph


title:
Anomalous electronic transport in Quasicrystals and related Complex
  Metallic Alloys

abstract:
  We analyze the transport properties in approximants of quasicrystals
alpha-AlMnSi, 1/1-AlCuFe and for the complex metallic phase lambda-AlMn. These
phases presents strong analogies in their local atomic structures and are
related to existing quasicrystalline phases. Experimentally they present
unusual transport properties with low conductivities and a mix of metallic-like
and insulating-like characteristics. We compute the band structure and the
quantum diffusion in the perfect structure without disorder and introduce
simple approximations that allow to treat the effect of disorder. Our results
demonstrate that the standard Bloch-Boltzmann theory is not applicable to these
intermetallic phases. Indeed their dispersion relation are flat indicating
small band velocities and corrections to quantum diffusion that are not taken
into account in the semi-classical Bloch-Boltzmann scheme become dominant. We
call this regime the small velocity regime. A simple Relaxation Time
Approximation to treat the effect of disorder allows us to reproduce the main
experimental facts on conductivity qualitatively and even quantitatively.


title:
Energy flux measurement from the dissipated energy in capillary wave
  turbulence

abstract:
  We study experimentally the influence of dissipation on stationary capillary
wave turbulence on the surface of a fluid by changing its viscosity. We observe
that the frequency power law scaling of the capillary spectrum departs
significantly from its theoretical value when the dissipation is increased. The
energy dissipated by capillary waves is also measured and found to increase
nonlinearly with the mean power injected within the fluid. Here, we propose an
experimental estimation of the energy flux at every scale of the capillary
cascade. The latter is found to be non constant through the scales. For fluids
of low enough viscosity, we found that both capillary spectrum scalings with
the frequency and the newly defined mean energy flux are in good agreement with
wave turbulence theory. The Kolmogorov-Zakharov constant is then experimentally
estimated and compared to its theoretical value.


title: The symmetric invariants of the centralizers and Slodowy grading

abstract:
  Let g be a finite-dimensional simple Lie algebra of rank r over an
algebraically closed field of characteristic zero, and let e be a nilpotent
element of g. Denote by g^e the centralizer of e in g and by S(g^e)^{g^e} the
algebra of symmetric invariants of g^e. We say that e is good if the
nullvariety of some r homogeneous elements of S(g^e)^{g^e} in the dual of g^{e}
has codimension r. If e is good then S(g^e)^{g^e} is polynomial. The main
result of this paper stipulates that if for some homogeneous generators of
S(g^e)^{g^e}, the initial homogeneous component of their restrictions to e+g^f
are algebraically independent, with (e,h,f) an sl2-triple of g, then e is good.
As applications, we obtain new examples of nilpotent elements that verify the
above polynomiality condition, in in simple Lie algebras of both classical and
exceptional types. We also give a counter-example in type D_7.


title:
Overview of the SOFIA Data Cycle System: An integrated set of tools and
  services for the SOFIA General Investigator

abstract:
  The Stratospheric Observatory for Infrared Astronomy (SOFIA) is an airborne
astronomical observatory comprised of a 2.5 meter infrared telescope mounted in
the aft section of a Boeing 747SP aircraft that flies at operational altitudes
between 37,000 and 45,00 feet, above 99% of atmospheric water vapor. During
routine operations, a host of instruments will be available to the astronomical
community including cameras and spectrographs in the near- to far-IR; a sub-mm
heterodyne receiver; and an high-speed occultation imager. One of the
challenges for SOFIA (and all observatories in general) is providing a uniform
set of tools that enable the non-expert General Investigator (GI) to propose,
plan, and obtain observations using a variety of very different instruments in
an easy and seamless manner. The SOFIA Data Cycle System (DCS) is an integrated
set of services and user tools for the SOFIA Science and Mission Operations GI
Program designed to address this challenge. Program activities supported by the
DCS include: proposal preparation and submission by the GI; proposal evaluation
by the telescope allocation committee and observatory staff; Astronomical
Observation Request (AOR) preparation and submission by the GI; observation and
mission planning by observatory staff; data processing and archiving; data
product distribution. In this poster paper we present an overview of the DCS
concepts, architecture, and user tools that are (or soon will be) available in
routine SOFIA operations. In addition, we present experience from the SOFIA
Basic Science program, and planned upgrades.


title: XIPE: the X-ray Imaging Polarimetry Explorer

abstract:
  X-ray polarimetry, sometimes alone, and sometimes coupled to spectral and
temporal variability measurements and to imaging, allows a wealth of physical
phenomena in astrophysics to be studied. X-ray polarimetry investigates the
acceleration process, for example, including those typical of magnetic
reconnection in solar flares, but also emission in the strong magnetic fields
of neutron stars and white dwarfs. It detects scattering in asymmetric
structures such as accretion disks and columns, and in the so-called molecular
torus and ionization cones. In addition, it allows fundamental physics in
regimes of gravity and of magnetic field intensity not accessible to
experiments on the Earth to be probed. Finally, models that describe
fundamental interactions (e.g. quantum gravity and the extension of the
Standard Model) can be tested. We describe in this paper the X-ray Imaging
Polarimetry Explorer (XIPE), proposed in June 2012 to the first ESA call for a
small mission with a launch in 2017 but not selected. XIPE is composed of two
out of the three existing JET-X telescopes with two Gas Pixel Detectors (GPD)
filled with a He-DME mixture at their focus and two additional GPDs filled with
pressurized Ar-DME facing the sun. The Minimum Detectable Polarization is 14 %
at 1 mCrab in 10E5 s (2-10 keV) and 0.6 % for an X10 class flare. The Half
Energy Width, measured at PANTER X-ray test facility (MPE, Germany) with JET-X
optics is 24 arcsec. XIPE takes advantage of a low-earth equatorial orbit with
Malindi as down-link station and of a Mission Operation Center (MOC) at INPE
(Brazil).


title:
Upper bounds on packing density for circular cylinders with high aspect
  ratio

abstract:
  In the early 1990s, A. Bezdek and W. Kuperberg used a relatively simple
argument to show a surprising result: The maximum packing density of circular
cylinders of infinite length in $\mathbb{R}^3$ is exactly $\pi/\sqrt{12}$, the
planar packing density of the circle. This paper modifies their method to prove
a bound on the packing density of finite length circular cylinders. In fact,
the maximum packing density for unit radius cylinders of length $t$ in
$\mathbb{R}^3$ is bounded above by $\pi/\sqrt{12} + 10/t$.


title: Homotopy theory of modules over diagrams of rings

abstract:
  Given a diagram of rings, one may consider the category of modules over them.
We are interested in the homotopy theory of categories of this type: given a
suitable diagram of model categories M(s) (as s runs through the diagram), we
consider the category of diagrams where the object X(s) at s comes from M(s).
We develop model structures on such categories of diagrams, and Quillen
adjunctions that relate categories based on different diagram shapes.
  Under certain conditions, cellularizations (or right Bousfield localizations)
of these adjunctions induce Quillen equivalences. As an application we show
that a cellularization of a category of modules over a diagram of ring spectra
(or differential graded rings) is Quillen equivalent to modules over the
associated inverse limit of the rings. Another application of the general
machinery here is given in work by the authors on algebraic models of rational
equivariant spectra. Some of this material originally appeared in the preprint
"An algebraic model for rational torus-equivariant stable homotopy theory",
arXiv:1101.2511, but has been generalized here.


title:
The optical transmission spectrum of the hot Jupiter HAT-P-32b: clouds
  explain the absence of broad spectral features?

abstract:
  We report Gemini-North GMOS observations of the inflated hot Jupiter
HAT-P-32b during two primary transits. We simultaneously observed two
comparison stars and used differential spectro-photometry to produce
multi-wavelength light curves. 'White' light curves and 29 'spectral' light
curves were extracted for each transit and analysed to refine the system
parameters and produce transmission spectra from 520-930nm in ~14nm bins. The
light curves contain time-varying white noise as well as time-correlated noise,
and we used a Gaussian process model to fit this complex noise model. Common
mode corrections derived from the white light curve fits were applied to the
spectral light curves which significantly improved our precision, reaching
typical uncertainties in the transit depth of ~2x10^-4, corresponding to about
half a pressure scale height. The low resolution transmission spectra are
consistent with a featureless model, and we can confidently rule out broad
features larger than about one scale height. The absence of Na/K wings or
prominent TiO/VO features is most easily explained by grey absorption from
clouds in the upper atmosphere, masking the spectral features. However, we
cannot confidently rule out clear atmosphere models with low abundances (~10^-3
solar) of TiO, VO or even metal hydrides masking the Na and K wings. A smaller
scale height or ionisation could also contribute to muted spectral features,
but alone are unable to to account for the absence of features reported here.


title:
Influence of Coulomb interaction on the anisotropic Dirac cone in
  graphene

abstract:
  Anisotropic Dirac cones can appear in a number of correlated electron
systems, such as cuprate superconductors and deformed graphene. We study the
influence of long-range Coulomb interaction on the physical properties of an
anisotropic graphene by using the renormalization group method and 1/N
expansion, where N is the flavor of Dirac fermions. Our explicit calculations
reveal that the anisotropic fermion velocities flow monotonously to an
isotropic fixed point in the lowest energy limit in clean graphene. We then
incorporate three sorts of disorders, including random chemical potential,
random gauge potential, and random mass, and show that the interplay of Coulomb
interaction and disorders can lead to rich and unusual behaviors. In the
presence of strong Coulomb interaction and a random chemical potential, the
fermion velocities are driven to vanish at low energies and the system turns
out to be an exotic anisotropic insulator. In the presence of Coulomb
interaction and other two types of disorders, the system flows to an isotropic
low-energy fixed point more rapidly than the clean case, and exhibits non-Fermi
liquid behaviors. We also investigate the nonperturbative effects of Coulomb
interaction, focusing on how the dynamical gap is affected by the velocity
anisotropy. It is found that the dynamical gap is enhanced (suppressed) as the
fermion velocities decrease (increase), but is suppressed as the velocity
anisotropy increases.


title: $Z\gamma$ production at hadron colliders in NNLO QCD

abstract:
  We consider the production of $Z\gamma$ pairs at hadron colliders. We report
on the first complete and fully differential computation of radiative
corrections at next-to-next-to-leading order in QCD perturbation theory. We
present selected numerical results for pp collisions at 7 TeV and compare them
to available LHC data. We find that the impact of the NNLO QCD corrections on
the fiducial cross section ranges between 4 and 15%, depending on the applied
cuts.


title: Kaczmarz Algorithm with Soft Constraints for User Interface Layout

abstract:
  The Kaczmarz method is an iterative method for solving large systems of
equations that projects iterates orthogonally onto the solution space of each
equation. In contrast to direct methods such as Gaussian elimination or
QR-factorization, this algorithm is efficient for problems with sparse
matrices, as they appear in constraint-based user interface (UI) layout
specifications. However, the Kaczmarz method as described in the literature has
its limitations: it considers only equality constraints and does not support
soft constraints, which makes it inapplicable to the UI layout problem.
  In this paper we extend the Kaczmarz method for solving specifications
containing soft constraints, using the prioritized IIS detection algorithm.
Furthermore, the performance and convergence of the proposed algorithms are
evaluated empirically using randomly generated UI layout specifications of
various sizes. The results show that these methods offer improvements in
performance over standard methods like Matlab's LINPROG, a well-known efficient
linear programming solver.


title:
Quantitative Characterizations of Regularity Properties of Collections
  of Sets

abstract:
  Several primal and dual characterizations of regularity properties of
collections of sets in normed linear spaces are discussed. Relationships
between regularity properties of collections of sets and those of set-valued
mappings are provided.


title:
The IceCube Neutrino Observatory Part II: Atmospheric and Diffuse UHE
  Neutrino Searches of All Flavors

abstract:
  Papers on atmospheric and diffuse UHE neutrino searches of all flavors
submitted to the 33nd International Cosmic Ray Conference (Rio de Janeiro 2013)
by the IceCube Collaboration.


title:
Calculation of Entailed Rank Constraints in Partially Non-Linear and
  Cyclic Models

abstract:
  The Trek Separation Theorem (Sullivant et al. 2010) states necessary and
sufficient conditions for a linear directed acyclic graphical model to entail
for all possible values of its linear coefficients that the rank of various
sub-matrices of the covariance matrix is less than or equal to n, for any given
n. In this paper, I extend the Trek Separation Theorem in two ways: I prove
that the same necessary and sufficient conditions apply even when the
generating model is partially non-linear and contains some cycles. This
justifies application of constraint-based causal search algorithms such as the
BuildPureClusters algorithm (Silva et al. 2006) for discovering the causal
structure of latent variable models to data generated by a wider class of
causal models that may contain non-linear and cyclic relations among the latent
variables.


title:
Herschel observations and a model for IRAS 08572+3915: a candidate for
  the most luminous infrared galaxy in the local (z < 0.2) Universe

abstract:
  We present Herschel photometry and spectroscopy, carried out as part of the
Herschel ULIRG survey (HERUS), and a model for the infrared to submillimetre
emission of the ultraluminous infrared galaxy IRAS 08572+3915. This source
shows one of the deepest known silicate absorption features and no polycyclic
aromatic hydrocarbon (PAH) emission. The model suggests that this object is
powered by an active galactic nucleus (AGN) with a fairly smooth torus viewed
almost edge-on and a very young starburst. According to our model the AGN
contributes about 90% of the total luminosity of 1.1 x 10^13 Lo, which is about
a factor of five higher than previous estimates. The large correction of the
luminosity is due to the anisotropy of the emission of the best fit torus.
Similar corrections may be necessary for other local and high-z analogs. This
correction implies that IRAS 08572+3915 at a redshift of 0.05835 may be the
nearest hyperluminous infrared galaxy and probably the most luminous infrared
galaxy in the local (z < 0.2) Universe. IRAS 08572+3915 shows a low ratio of
[CII] to IR luminosity (log L_[CII]/L_{IR} < -3.8) and a [OI]63um to [CII]158um
line ratio of about 1 that supports the model presented in this letter.


title: The IceCube Neutrino Observatory Part III: Cosmic Rays

abstract:
  Papers on cosmic rays submitted to the 33nd International Cosmic Ray
Conference (Rio de Janeiro 2013) by the IceCube Collaboration.


title:
The IceCube Neutrino Observatory Part IV: Searches for Dark Matter and
  Exotic Particles

abstract:
  Papers on searches for Dark Matter and exotic particles submitted to the 33nd
International Cosmic Ray Conference (Rio de Janeiro 2013) by the IceCube
Collaboration.


title:
The IceCube Neutrino Observatory Part V: Neutrino Oscillations and
  Supernova Searches

abstract:
  Papers on neutrino oscillation and supernova searches submitted to the 33nd
International Cosmic Ray Conference (Rio de Janeiro 2013) by the IceCube
Collaboration.


title:
Analyzing the Reduced Required BS Density due to CoMP in Cellular
  Networks

abstract:
  In this paper we investigate the benefit of base station (BS) cooperation in
the uplink of coordinated multi-point (CoMP) networks. Our figure of merit is
the required BS density required to meet a chosen rate coverage. Our model
assumes a 2-D network of BSs on a regular hexagonal lattice in which path loss,
lognormal shadowing and Rayleigh fading affect the signal received from users.
Accurate closed-form expressions are first presented for the sum-rate coverage
probability and ergodic sum-rate at each point of the cooperation region. Then,
for a chosen quality of user rate, the required density of BS is derived based
on the minimum value of rate coverage probability in the cooperation region.
The approach guarantees that the achievable rate in the entire coverage region
is above a target rate with chosen probability. The formulation allows
comparison between different orders of BS cooperation, quantifying the reduced
required BS density from higher orders of cooperation.


title:
The IceCube Neutrino Observatory Part VI: Ice Properties, Reconstruction
  and Future Developments

abstract:
  Papers on ice properties, reconstruction and future developments submitted to
the 33nd International Cosmic Ray Conference (Rio de Janeiro 2013) by the
IceCube Collaboration.


title: A new type of nonsingular black-hole solution in general relativity

abstract:
  Certain exact solutions of the Einstein field equations over
nonsimply-connected manifolds are reviewed. These solutions are spherically
symmetric and have no curvature singularity. They provide a regularization of
the standard Schwarzschild solution with a curvature singularity at the center.
Spherically symmetric collapse of matter in $\mathbb{R}^4$ may result in these
nonsingular black-hole solutions, if quantum-gravity effects allow for topology
change near the center or if nontrivial topology is already present as a
remnant from a quantum spacetime foam.


title: Vortex Ring Dynamics in Trapped Bose-Einstein Condensates

abstract:
  We use the time-dependent Gross-Pitaevskii equation to study the motion of a
vortex ring produced by phase imprinting on an elongated cloud of cold atoms.
Our approach models the experiments of Yefsah et. al. [Nature \textbf{499},
426] on $^6$Li in the BEC regime where the fermions are tightly bound into
bosonic dimers. We find ring oscillation periods which are much larger than the
period of the axial harmonic trap. Our results lend further strength to Bulgac
et. al.'s arguments [arXiv: 1306.4266] that the "heavy solitons" seen in those
experiments are actually vortex rings. We numerically calculate the periods of
oscillation for the vortex rings as a function of interaction strength, trap
aspect ratio, and minimum vortex ring radius. In the presence of axial
anisotropies the rings undergo complicated internal dynamics where they break
into sets of vortex lines, then later combine into rings. These structures
oscillate with a similar frequency to simple axially symmetric rings.


title: Geometry of Periodic Monopoles

abstract:
  BPS monopoles on $\mathbb{R}^2\times S^1$ correspond, via the generalized
Nahm transform, to certain solutions of the Hitchin equations on the cylinder
$\mathbb{R}\times S^1$. The moduli space M of two monopoles with their
centre-of-mass fixed is a 4-dimensional manifold with a natural hyperk\"ahler
metric, and its geodesics correspond to slow-motion monopole scattering. The
purpose of this paper is to study the geometry of M in terms of the
Nahm/Hitchin data, i.e. in terms of structures on $\mathbb{R}\times S^1$. In
particular, we identify the moduli, derive the asymptotic metric on M, and
discuss several geodesic surfaces and geodesics on M. The latter include novel
examples of monopole dynamics.


title: Constructing co-Higgs bundles on CP^2

abstract:
  On a complex manifold, a co-Higgs bundle is a holomorphic vector bundle with
an endomorphism twisted by the tangent bundle. The notion of generalized
holomorphic bundle in Hitchin's generalized geometry coincides with that of
co-Higgs bundle when the generalized complex manifold is ordinary complex.
Schwarzenberger's rank-2 vector bundle on the projective plane, constructed
from a line bundle on the double cover CP^1 \times CP^1 \to CP^2, is naturally
a co-Higgs bundle, with the twisted endomorphism, or "Higgs field", also
descending from the double cover. Allowing the branch conic to vary, we find
that Schwarzenberger bundles give rise to an 8-dimensional moduli space of
co-Higgs bundles. After studying the deformation theory for co-Higgs bundles on
complex manifolds, we conclude that a co-Higgs bundle arising from a
Schwarzenberger bundle with nonzero Higgs field is rigid, in the sense that a
nearby deformation is again Schwarzenberger.


title:
Gap probabilities for the Generalized Bessel process: a Riemann-Hilbert
  approach

abstract:
  We consider the gap probability for the Generalized Bessel process in the
single-time and multi-time case. We prove that the scalar and matrix Fredholm
determinants of such process can be expressed in terms of determinants of
Its-Izergin-Korepin-Slavnov integrable kernels and thus related to suitable
Riemann-Hilbert problems. In the single-time case, we construct a Lax pair
formalism, while in the multi-time case we explicitly define a new multi-time
kernel to study.


title: Origins of Nonlocality near the Dirac Point in Graphene

abstract:
  We present an experimental study of nonlocal electrical signals near the
Dirac point in graphene. The in-plane magnetic field dependence of the nonlocal
signal confirms the role of spin in this effect, as expected from recent
predictions of Zeeman spin Hall effect in graphene, but our experiments show
that thermo-magneto-electric effects also contribute to nonlocality, and the
effect is sometimes stronger than that due to spin. Thermal effects are seen to
be very sensitive to sample details that do not influence other transport
parameters.


title:
From frustration to glassiness via quantum fluctuations and random
  tiling with exotic entropy

abstract:
  When magnetic moments (spins) are regularly arranged in a geometry of a
triangular motif, the spins may not satisfy simultaneously their interactions
with their neighbors. This phenomenon, called frustration, leads to numerous
energetically equivalent magnetic states (ground states), which results in
exotic states such as spin liquid and spin ice. Here we report an alternative
situation: a system that, classically, is to be a liquid in the clean limit
freezes into a glassy state induced by quantum fluctuations. The case in point
is a frustrated magnet in which spins are arranged in a triangular network of
bi-pyramids. When taking into account quantum corrections, the classical
degeneracy is broken into a set of local minima in a rugged energy landscape,
which are separated by large energy barriers, over a finite number of
degenerate, periodic, ground states. The appearance of large barriers is due to
the absence of local zero-energy modes that are typical in spin-liquid
candidate systems. We establish this by mapping the set of local energy minima
states into a tiling with colored hexagonal tiles. We show that the system
exhibits a large number of aperiodic tessellations. The configuration entropy
of the local minima is extremely sensitive to boundary conditions, scaling with
the boundary length rather than its volume. The low temperature thermodynamics
is also discussed to compare it with other glassy materials.


title: Eulerian cube complexes and reciprocity

abstract:
  Let $G$ be the fundamental group of a compact nonpositively curved cube
complex $Y$. With respect to a basepoint $x$, one obtains an integer-valued
length function on $G$ by counting the number of edges in a minimal length
edge-path representing each group element. The growth series of $G$ with
respect to $x$ is then defined to be the power series $G_x(t)=\sum_g t^{|g|}$
where $|g|$ denotes the length of $g$. Using the fact that $G$ admits a
suitable automatic structure, $G_x(t)$ can be shown to be a rational function.
We prove that if $Y$ is a manifold of dimension $n$, then this rational
function satisfies the reciprocity formula $G_x(t^{-1})=(-1)^n G_x(t)$. We
prove the formula in a more general setting, replacing the group with the
fundamental groupoid, replacing the growth series with the characteristic
series for a suitable regular language, and only assuming $Y$ is Eulerian.


title: On the zeros of L-functions

abstract:
  We generalize our recent construction of the zeros of the Riemann
$\zeta$-function to two infinite classes of $L$-functions, Dirichlet
$L$-functions and those based on level one modular forms. More specifically, we
show that there are an infinite number of zeros on the critical line which are
in one-to-one correspondence with the zeros of the cosine function, and thus
enumerated by an integer $n$. We obtain an exact equation on the critical line
that determines the $n$-th zero of these $L$-functions. We show that the
counting formula on the critical line derived from such an equation agrees with
the known counting formula on the entire critical strip. We provide numerical
evidence supporting our statements, by computing numerical solutions of this
equation, yielding $L$-zeros to high accuracy. We study in detail the
$L$-function for the modular form based on the Ramanujan $\tau$-function, which
is closely related to the bosonic string partition function. The same analysis
for a more general class of $L$-functions is also considered.


title:
Radio Detection of A Candidate Neutron Star Associated with Galactic
  Center Supernova Remnant Sagittarius A East

abstract:
  We report the VLA detection of the radio counterpart of the X-ray object
referred to as the "Cannonball", which has been proposed to be the remnant
neutron star resulting from the creation of the Galactic Center supernova
remnant, Sagittarius A East. The radio object was detected both in our new VLA
image from observations in 2012 at 5.5 GHz and in archival VLA images from
observations in 1987 at 4.75 GHz and in the period from 1990 to 2002 at 8.31
GHz. The radio morphology of this object is characterized as a compact,
partially resolved point source located at the northern tip of a radio "tongue"
similar to the X-ray structure observed by Chandra. Behind the Cannonball, a
radio counterpart to the X-ray plume is observed. This object consists of a
broad radio plume with a size of 30\arcsec$\times$15\arcsec, followed by a
linear tail having a length of 30\arcsec. The compact head and broad plume
sources appear to have relatively flat spectra ($\propto\nu^\alpha$) with mean
values of $\alpha=-0.44\pm0.08$ and $-0.10\pm0.02$, respectively; and the
linear tail shows a steep spectrum with the mean value of $-1.94\pm0.05$. The
total radio luminosity integrated from these components is $\sim8\times10^{33}$
erg s$^{-1}$, while the emission from the head and tongue amounts for only
$\sim1.5\times10^{31}$ erg s$^{-1}$. Based on the images obtained from the two
epochs' observations at 5 GHz, we infer the proper motion of the object:
$\mu_\alpha = 0.001 \pm0.003$ arcsec yr$^{-1}$ and $\mu_\delta = 0.013
\pm0.003$ arcsec yr$^{-1}$. With an implied velocity of 500 km s$^{-1}$, a
plausible model can be constructed in which a runaway neutron star surrounded
by a pulsar wind nebula was created in the event that produced Sgr A East. The
inferred age of this object, assuming that its origin coincides with the center
of Sgr A East, is approximately 9000 years.


title: Random sequential adsorption of trimers and hexamers

abstract:
  Adsorption of trimers and hexamers built of identical spheres was studied
numerically using the Random Sequential Adsorption (RSA) algorithm. Particles
were adsorbed on a two dimensional, flat and homogeneous surface. Numerical
simulations allow to establish the maximal random coverage ratio, RSA kinetics
as well as the Available Surface Function (ASF), which is crucial for
determining kinetics of the adsorption process obtained experimentally.
Additionally, the density autocorrelation function was measured. All the
results were compared with previous results obtained for spheres, dimers and
tetramers.


title:
A Very Intense Neutrino Super Beam Experiment for Leptonic CP Violation
  Discovery based on the European Spallation Source Linac: A Snowmass 2013
  White Paper

abstract:
  Very intense neutrino beams and large neutrino detectors will be needed in
order to enable the discovery of CP violation in the leptonic sector. We
propose to use the proton linac of the European Spallation Source currently
under construction in Lund, Sweden to deliver, in parallel with the spallation
neutron production, a very intense, cost effective and high performance
neutrino beam. The baseline program for the European Spallation Source linac is
that it will be fully operational at 5 MW average power by 2022, producing 2
GeV 2.86 ms long proton pulses at a rate of 14 Hz. Our proposal is to upgrade
the linac to 10 MW average power and 28 Hz, producing 14 pulses/s for neutron
production and 14 pulses/s for neutrino production. Furthermore, because of the
high current required in the pulsed neutrino horn, the length of the pulses
used for neutrino production needs to be compressed to a few $\mu$s with the
aid of an accumulator ring. A long baseline experiment using this Super Beam
and a megaton underground Water Cherenkov detector located in existing mines
300-600 km from Lund will make it possible to discover leptonic CP violation at
5 $\sigma$ significance level in up to 50% of the leptonic Dirac CP-violating
phase range. This experiment could also determine the neutrino mass hierarchy
at a significance level of more than 3 $\sigma$ if this issue will not already
have been settled by other experiments by then. The mass hierarchy performance
could be increased by combining the neutrino beam results with those obtained
from atmospheric neutrinos detected by the same large volume detector. This
detector will also be used to measure the proton lifetime, detect cosmological
neutrinos and neutrinos from supernova explosions. Results on the sensitivity
to leptonic CP violation and the neutrino mass hierarchy are presented.

categories: hep-ex hep-ph physics.acc-ph physics.ins-det


title:
Proximity effect of spin orbit coupling in Pt/Co2FeAl and Pt/Permalloy
  bilayers_810571

abstract:
  Proximity effect of spin orbit coupling is investigated through anomalous
Hall effect in Pt/Co2FeAl and Pt/Permalloy bilayers. A series of nontrivial
magnetotransport behaviors, resulting from a strong impact of phonons on skew
scattering, is observed in these films with ultrathin ferromagnetic layers. The
parameters representing skew scattering, side jump and intrinsic contributions
are dramatically enhanced when the ferromagnetic layer is very thin, and they
have clear linear dependences on the reciprocal of ferromagnetic layer
thickness, indicating a powerful influence of Pt/Ferromagnet interface. Further
study on Cu/Co2FeAl and Ta/Co2FeAl bilayers reveals that a simple interface
scattering without intense spin orbit coupling is not sufficient to trigger
such a phenomenon. The proximity effect of spin orbit coupling is thus
suggested to occur at the Pt/Ferromagnet interface, and as a result quite large
anomalous Hall angle (0.036) and Nernst angle (0.23) are confirmed in the
Pt/CFA films at room temperature.


title: Neutrino physics with multi-ton scale liquid xenon detectors

abstract:
  We study the sensitivity of large-scale xenon detectors to low-energy solar
neutrinos, to coherent neutrino-nucleus scattering and to neutrinoless double
beta decay. As a concrete example, we consider the xenon part of the proposed
DARWIN (Dark Matter WIMP Search with Noble Liquids) experiment. We perform
detailed Monte Carlo simulations of the expected backgrounds, considering
realistic energy resolutions and thresholds in the detector. In a low-energy
window of 2-30 keV, where the sensitivity to solar pp and $^7$Be-neutrinos is
highest, an integrated pp-neutrino rate of 5900 events can be reached in a
fiducial mass of 14 tons of natural xenon, after 5 years of data. The
pp-neutrino flux could thus be measured with a statistical uncertainty around
1%, reaching the precision of solar model predictions. These low-energy solar
neutrinos will be the limiting background to the dark matter search channel for
WIMP-nucleon cross sections below $\sim$2$\times$10$^{-48}$ cm$^2$ and WIMP
masses around 50 GeV$\cdot$c$^{-2}$, for an assumed 99.5% rejection of
electronic recoils due to elastic neutrino-electron scatters. Nuclear recoils
from coherent scattering of solar neutrinos will limit the sensitivity to WIMP
masses below $\sim$6 GeV$\cdot$c$^{-2}$ to cross sections above
$\sim$4$\times$10$^{-45}$cm$^2$. DARWIN could reach a competitive half-life
sensitivity of 5.6$\times$10$^{26}$ y to the neutrinoless double beta decay of
$^{136}$Xe after 5 years of data, using 6 tons of natural xenon in the central
detector region.

categories: physics.ins-det astro-ph.SR hep-ph nucl-ex


title: Large regular bipartite graphs with median eigenvalue 1

abstract:
  A recent result of one of the authors says that every connected subcubic
bipartite graph that is not isomorphic to the Heawood graph has at least one,
and in fact a positive proportion of its eigenvalues in the interval [-1,1]. We
construct an infinite family of connected cubic bipartite graphs which have no
eigenvalues in the open interval (-1,1), thus showing that the interval [-1,1]
cannot be replaced by any smaller symmetric subinterval even when allowing any
finite number of exceptions. Similar examples with vertices of larger degrees
are considered and it is also shown that their eigenvalue distribution has
somewhat unusual properties. By taking limits of these graphs, we obtain
examples of infinite vertex-transitive r-regular graphs for every r\ge3, whose
spectrum consists of points $\pm1$ together with intervals [r-2,r] and
[-r,-r+2]. These examples shed some light onto a question communicated by
Daniel Lenz and Matthias Keller with motivation in relation to the Baum-Connes
conjecture.


title: Quasiconformal homogeneity and subgroups of the mapping class group

abstract:
  In the vein of Bonfert-Taylor, Bridgeman, Canary, and Taylor we introduce the
notion of quasiconformal homogeneity for closed oriented hyperbolic surfaces
restricted to subgroups of the mapping class group. We find uniform lower
bounds for the associated quasiconformal homogeneity constants across all
closed hyperbolic surfaces in several cases, including the Torelli group,
congruence subgroups, and pure cyclic subgroups. Further, we introduce a
counting argument providing a possible path to exploring a uniform lower bound
for the nonrestricted quasiconformal homogeneity constant across all closed
hyperbolic surfaces.


title:
Non-equilibrium Functional Renormalization for Driven-Dissipative
  Bose-Einstein Condensation

abstract:
  We present a comprehensive analysis of critical behavior in the
driven-dissipative Bose condensation transition in three spatial dimensions.
Starting point is a microscopic description of the system in terms of a
many-body quantum master equation, where coherent and driven-dissipative
dynamics occur on an equal footing. An equivalent Keldysh real time functional
integral reformulation opens up the problem to a practical evaluation using the
tools of quantum field theory. In particular, we develop a functional
renormalization group approach to quantitatively explore the universality class
of this stationary non-equilibrium system. Key results comprise the emergence
of an asymptotic thermalization of the distribution function, while manifest
non-equilibrium properties are witnessed in the response properties in terms of
a new, independent critical exponent. Thus the driven-dissipative microscopic
nature is seen to bear observable consequences on the largest length scales.
The absence of two symmetries present in closed equilibrium systems -
underlying particle number conservation and detailed balance, respectively - is
identified as the root of this new non-equilibrium critical behavior. Our
results are relevant for broad ranges of open quantum systems on the interface
of quantum optics and many-body physics, from exciton-polariton condensates to
cold atomic gases.


title: On the Kolmogorov set for Many-Body Problems

abstract:
  I defended my PhD Thesis in Rome, Universit\`a Roma Tre, on April, 23, 2009,
under the direction of Professor Luigi Chierchia. The judging committee was
composed by Professors M. Berti, A. Celletti, C. Falcolini, J. F\'ejoz.
Professors M. Berti and J. F\'ejoz refereed my thesis. The main result of my
thesis is the first direct proof (the first general proof was given in [J.
F\'ejoz, ETDS, 2004]) of a famous statement by V. I. Arnold (1963), usually
referred to as "Arnold's Planetary Theorem". My proof of Arnold's Planetary
Theorem relies on the rediscovery, during the year 2008, of a symplectic set of
action-angle variables (described in \S 4 of my thesis) which perform
explicitly the reduction of rotation invariance of the system. Indeed, even
though in a different form, they had been previously considered by [F. Boigey,
Cel. Mech. Dyn. Astr., 1982] and [A. Deprit, Cel. Mech. Dyn. Astr., 1983]. The
version I found in 2008 corresponds to the "planetary" form of Boigey-Deprit
variables, since it includes the elliptic elements of the instantaneous
ellipses of the planets around the sun and for this reason is especially fitted
to this problem .
  I then regularized "my" planetary variables to include co-planar and
co-circular motions. This regularization leads to a set of mixed action-angle
and rectangular variables analogous to Poincar\'e' variables but better fitted
to rotation invariance of the system, since they exhibit a cyclic couple of
conjugated variables. I finally applied my regularized variables to the
problem, checked non-trivial torsion and obtained the proof of the theorem.
  I wish to thank J. F\'ejoz for mentioning my contribution to the proof of
Arnold's Theorem, and especially my rediscovery of Deprit's reduction, in his
paper [J. Fejoz, DCDS-A, 2013].


title: Partonic Picture of Generalized Transverse Momentum Distributions

abstract:
  We argue that due to parity constraints, the helicity combination of the
purely momentum space counterparts of the Wigner distributions -- the
generalized transverse momentum distributions -- that describes the
configuration of an unpolarized quark in a longitudinally polarized nucleon,
can enter the deeply virtual Compton scattering amplitude only through matrix
elements involving a final state interaction. The relevant matrix elements in
turn involve light cone operators projections in the transverse direction, or
they appear in the deeply virtual Compton scattering amplitude at twist three.
Orbital angular momentum or the spin structure of the nucleon was a major
reason for these various distributions and amplitudes to have been introduced.
We show that twist three contributions to deeply virtual Compton scattering
provide observables related to orbital angular momentum.


title: PyR@TE: Renormalization Group Equations for General Gauge Theories

abstract:
  Although the two-loop renormalization group equations for a general gauge
field theory have been known for quite some time, deriving them for specific
models has often been difficult in practice. This is mainly due to the fact
that, albeit straightforward, the involved calculations are quite long, tedious
and prone to error. The present work is an attempt to facilitate the practical
use of the renormalization group equations in model building. To that end, we
have developed two completely independent sets of programs written in Python
and Mathematica, respectively. The Mathematica scripts will be part of an
upcoming release of SARAH 4. The present article describes the collection of
Python routines that we dubbed PyR@TE which is an acronym for "Python
Renormalization group equations At Two-loop for Everyone". In PyR@TE, once the
user specifies the gauge group and the particle content of the model, the
routines automatically generate the full two-loop renormalization group
equations for all (dimensionless and dimensionful) parameters. The results can
optionally be exported to Latex and Mathematica, or stored in a Python data
structure for further processing by other programs. For ease of use, we have
implemented an interactive mode for PyR@TE in form of an IPython Notebook. As a
first application, we have generated with PyR@TE the renormalization group
equations for several non-supersymmetric extensions of the Standard Model and
found some discrepancies with the existing literature.


title: Controlling Contagion Processes in Time-Varying Networks

abstract:
  The vast majority of strategies aimed at controlling contagion processes on
networks considers the connectivity pattern of the system as either quenched or
annealed. However, in the real world many networks are highly dynamical and
evolve in time concurrently to the contagion process. Here, we derive an
analytical framework for the study of control strategies specifically devised
for time-varying networks. We consider the removal/immunization of individual
nodes according the their activity in the network and develop a block variable
mean-field approach that allows the derivation of the equations describing the
evolution of the contagion process concurrently to the network dynamic. We
derive the critical immunization threshold and assess the effectiveness of the
control strategies. Finally, we validate the theoretical picture by simulating
numerically the information spreading process and control strategies in both
synthetic networks and a large-scale, real-world mobile telephone call dataset


title: Lattice Model for Fermionic Toric Code

abstract:
  The Z_2 topological order in Z_2 spin liquid and in exactly soluble Kitaev
toric code model is the simplest topological order for 2+1D bosonic systems.
More general 2+1D bosonic topologically ordered states can be constructed via
exact soluble string-net models. However, the most important topologically
ordered phases of matter are arguably the fermionic fractional quantum Hall
states. Topological phases of matter for fermion systems are strictly richer
than their bosonic counterparts because locality has different meanings for the
two kinds of systems. In this paper, we describe a simple fermionic version of
the toric code model to illustrate many salient features of fermionic exactly
soluble models and fermionic topologically ordered states.


title: Precision spectroscopy by photon-recoil signal amplification

abstract:
  Precision spectroscopy of atomic and molecular ions offers a window to new
physics, but is typically limited to species with a cycling transition for
laser cooling and detection. Quantum logic spectroscopy has overcome this
limitation for species with long-lived excited states. Here, we extend quantum
logic spectroscopy to fast, dipole-allowed transitions and apply it to perform
an absolute frequency measurement. We detect the absorption of photons by the
spectroscopically investigated ion through the photon recoil imparted on a
co-trapped ion of a different species, on which we can perform efficient
quantum logic detection techniques. This amplifies the recoil signal from a few
absorbed photons to thousands of fluorescence photons. We resolve the line
center of a dipole-allowed transition in 40Ca+ to 1/300 of its observed
linewidth, rendering this measurement one of the most accurate of a broad
transition. The simplicity and versatility of this approach enables
spectroscopy of many previously inaccessible species.


title: Radical re-appraisal of water structure in hydrophilic confinement

abstract:
  The structure of water confined in MCM41 silica cylindrical pores is studied
to determine if confined water really is simply a version of the bulk liquid
which can be substantially supercooled without crystallisation. A combination
of total neutron scattering from the porous silica, both wet and dry,and
computer simulation using a realistic model of the scattering substrate isused.
The water in the pore is divided into three regions: core, interfacial and
overlap. The average local densities of water in these simulations are found to
be about 20% lower than bulk water density, while the density in the core
region is below, but closer to, the bulk density. There is a decrease in both
local and core densities when the temperature is lowered from 298K to 210K. The
radical proposal is made here that water in hydrophilic confinement is under
significant tension, around -100MPa, inside the pore.


title:
Probing the axion-photon coupling: phenomenological and experimental
  perspectives. A snowmass white paper

abstract:
  We present a brief overview of the ongoing searches for the axion particle
via its coupling to photons. Both the classical QCD axions and more recently
proposed Axion-Like-Particles are considered. Astrophysical bounds on the
axion-photon coupling come from considerations of stellar energy loss during
Helium burning, in both low- and high-mass stars. Helioscopes look for
back-conversion of solar axions into x-ray photons in strong laboratory
magnetic fields. Finally, haloscopes aim to detect dark matter axions in our
galactic halo. Both types of searches are expecting significant advances in the
future, which will enable them to probe large, well-motivated parts of the
parameter space below the stellar cooling bounds.


title: Realistic Implementation of Massive Yang Mills for rho and a1 Mesons

abstract:
  We revisit the massive Yang-Mills approach to implement axial-/vector mesons
into the chiral pion Lagrangian. Employing the non-linear realization of chiral
symmetry, we compute vector and axial-vector spectral functions. This includes,
for the first time, a resummation of the $\rho$ propagator in the $a_1$
selfenergy while maintaining a partially conserved axial-vector current (PCAC).
A realistic $\rho$ propagator, combined with a recent idea of a chirally
invariant continuum in the vector and axial-vector channels, turns out be
critical to obtain a quantitative description of hadronic $\tau$-decay data
which has not been achieved before in local-gauge approaches to the chiral
lagrangian. The thus obtained model provides a realistic basis to rigorously
address the long-standing question of chiral symmetry restoration in the
context of dilepton data in heavy-ion collisions.


title: Holographic Baryons from Oblate Instantons

abstract:
  We investigate properties of baryons in a family of holographic field
theories related to the Sakai-Sugimoto model of holographic QCD. Starting with
the $N_f=2$ Sakai-Sugimoto model, we truncate to a 5D Yang-Mills action for the
gauge fields associated with the noncompact directions of the flavour
D8-branes. We define a free parameter $\gamma$ that controls the strength of
this Yang-Mills term relative to the Chern-Simons term that couples the abelian
gauge field to the SU(2) instanton density. Moving away from $\gamma = 0$
should incorporate some of the effects of taking the Sakai-Sugimoto model away
from large 't Hooft coupling $\lambda$. In this case, the baryon ground state
corresponds to an oblate SU(2) instanton on the bulk flavour branes: the usual
SO(4) symmetric instanton is deformed to spread more along the field theory
directions than the radial direction. We numerically construct these
anisotropic instanton solutions for various values of $\gamma$ and calculate
the mass and baryon charge profile of the corresponding baryons. Using the
value $\gamma = 2.55$ that has been found to best fit the mesonic spectrum of
QCD, we find a value for the baryon mass of 1.19 GeV, significantly more
realistic than the value 1.60 GeV computed previously using an SO(4) symmetric
ansatz for the instanton.


title: Strong Higgs Interactions at a Linear Collider

abstract:
  We study the impact of Higgs precision measurements at a high-energy and
high-luminosity linear electron positron collider, such as CLIC or the ILC, on
the parameter space of a strongly interacting Higgs boson. Some combination of
anomalous couplings are already tightly constrained by current fits to
electroweak observables. However, even small deviations in the cross sections
of single and double Higgs production, or the mere detection of a triple Higgs
final state, can help establish whether it is a composite state and whether or
not it emerges as a pseudo-Nambu-Goldstone boson from an underlying broken
symmetry. We obtain an estimate of the ILC and CLIC sensitivities on the
anomalous Higgs couplings from a study of WW scattering and hh production which
can be translated into a sensitivity on the compositeness scale 4\pi f, or
equivalently on the degree of compositeness \xi=v^2/f^2. We summarize the
current experimental constraints, from electroweak data and direct resonance
searches, and the expected reach of the LHC and CLIC on \xi and on the scale of
the new resonances.


title: Maximum Spectral Luminous Efficacy of White Light

abstract:
  As lighting efficiency improves, it is useful to understand the theoretical
limits to luminous efficacy for light that we perceive as white. Independent of
the efficiency with which photons are generated, there exists a
spectrally-imposed limit to the luminous efficacy of any source of photons. We
find that, depending on the acceptable bandpass and---to a lesser extent---the
color temperature of the light, the ideal white light source achieves a
spectral luminous efficacy of 250--370 lm/W. This is consistent with previous
calculations, but here we explore the maximum luminous efficacy as a function
of photopic sensitivity threshold, color temperature, and color rendering
index; deriving peak performance as a function of all three parameters. We also
present example experimental spectra from a variety of light sources,
quantifying the intrinsic efficacy of their spectral distributions.


title: A sum rule for the critical zeros of $\zeta(s)$

abstract:
  The two-parameter series over the critical zeros of the Riemann Zeta function
  $Re\sum_{\rho}\frac{x^{(\rho-a)/4a}}{\sqrt{\rho-a}\sinh[\frac{\pi}{2}\sqrt{\frac{\rho-a}{a}}]\zeta'(\rho)}$
  is evaluated in terms of $\zeta(s)$ on the real axis.


title:
Yakutsk array radio emission registration results in the energy range of
  3*10^16-5*10^18 eV

abstract:
  This paper presents the set of measurements of ultra-high energy air shower
radio emission at frequency 32 MHz in period of 2008-2012. The showers are
selected by geomagnetic and azimuth angles and then by the energy in three
intervals: 3*10^16 3*10^17 eV, 3*10^17 6*10^17 eV and 6*10^17 5*10^18 eV. In
each energy interval average lateral distribution function using mathematically
averaged data from antennas with different directions are plotted. In the
paper, using experimental data the dependence of radio signal averaged
amplitude from geomagnetic angle, the shower axis distance and the energy are
determined. Depth of maximum of cosmic ray showers Xmax for the given energy
range is evaluated. The evaluation is made according QGSJET model calculations
and average lateral distribution function shape.


title:
Anisotropic two-dimensional electron gas at SrTiO3(110) protected by its
  native overlayer

abstract:
  Two dimensional electron gases (2DEGs) at a oxide heterostructures are
attracting considerable attention, as these might substitute conventional
semiconductors for novel electronic devices [1]. Here we present a minimal
set-up for such a 2DEG -the SrTiO3(110)-(4 x 1) surface, natively terminated
with one monolayer of chemically-inert titania. Oxygen vacancies induced by
synchrotron radiation migrate under- neath this overlayer, this leads to a
confining potential and electron doping such that a 2DEG develops. Our angular
resolved photoemission spectroscopy (ARPES) and theoretical results show that
confinement along (110) is strikingly different from a (001) crystal
orientation. In particular the quantized subbands show a surprising
"semi-heavy" band, in contrast to the analogue in the bulk, and a high
electronic anisotropy. This anisotropy and even the effective mass of the (110)
2DEG is tunable by doping, offering a high flexibility to engineer the
properties of this system.


title:
Searches for resonances in the tb and tc final states at the
  high-luminosity LHC

abstract:
  We study resonances decaying to one top quark and one additional quark (b or
c) at the low- luminosity and high-luminosity 14 TeV LHC and at a future 33 TeV
hadron collider in the context of Snowmass 2013. A heavy W boson that
preferentially couples to quarks can be found through its decay to tb. A
Kaluza-Klein gluon might have a significant branching ratio to tc. The final
state in these searches has a lepton and neutrino from a W boson decay plus two
jets, at least one of which is b-tagged. We give expected limits as a function
of W boson and KKg masses for different collider energy and integrated
luminosity options.


title:
Robust Quantification of Galaxy Cluster Morphology Using Asymmetry and
  Central Concentration

abstract:
  We present a novel quantitative scheme of cluster classification based on the
morphological properties that are manifested in X-ray images. We use a
conventional radial surface brightness concentration parameter (c_{SB}) as
defined previously by others, and a new asymmetry parameter, which we define in
this paper. Our asymmetry parameter, which we refer to as photon asymmetry
($A_{phot}), was developed as a robust substructure statistic for cluster
observations with only a few thousand counts. To demonstrate that photon
asymmetry exhibits better stability than currently popular power ratios and
centroid shifts, we artificially degrade the X-ray image quality by: (a) adding
extra background counts, (b) eliminating a fraction of the counts, (c)
increasing the width of the smoothing kernel, and (d) simulating cluster
observations at higher redshift. The asymmetry statistic presented here has a
smaller statistical uncertainty than competing substructure parameters,
allowing for low levels of substructure to be measured with confidence.
A_{phot} is less sensitive to the total number of counts than competing
substructure statistics, making it an ideal candidate for quantifying
substructure in samples of distant clusters covering wide range of
observational S/N. Additionally, we show that the asymmetry-concentration
classification separates relaxed, cool core clusters from
morphologically-disturbed mergers, in agreement with by-eye classifications.
Our algorithms, freely available as Python scripts
(https://github.com/ndaniyar/aphot) are completely automatic and can be used to
rapidly classify galaxy cluster morphology for large numbers of clusters
without human intervention.


title: Are gamma-ray bursts the same at high redshift and low redshift?

abstract:
  The majority of Swift gamma-ray bursts (GRBs) observed at z > 6 have prompt
durations of T90 < 30s, which, at first sight, is surprising given that
cosmological time-dilation means this corresponds to < 5s in their rest frames.
We have tested whether these high-redshift GRBs are consistent with being drawn
from the same population as those observed at low-redshift by comparing them to
an artificially red-shifted sample of 114 z < 4 bursts. This is accomplished
using two methods to produce realistic high-z simulations of light curves based
on the observed characteristics of the low-z sample. In Method 1 we use the
Swift/BAT data directly, taking the photons detected in the harder bands to
predict what would be seen in the softest energy band if the burst were seen at
higher-z. In Method 2 we fit the light curves with a model, and use that to
extrapolate the expected behaviour over the whole BAT energy range at any
redshift. Based on the results of Method 2, a K-S test of their durations finds
a ~1% probability that the high-z GRB sample is drawn from the same population
as the bright low-z sample. Although apparently marginally significant, we must
bear in mind that this test was partially a posteriori, since the rest-frame
short durations of several high-z bursts motivated the study in the first
instance.


title: The surprising Crab pulsar and its nebula: A review

abstract:
  The Crab nebula and its pulsar (referred to together as "Crab") have
historically played a central role in astrophysics. True to their legacy,
several unique discoveries have been made recently. The Crab was found to emit
gamma-ray pulsations up to energies of 400 GeV, beyond what was previously
expected from pulsars. Strong gamma-ray flares, of durations of a few days were
discovered from within the nebula, while the source was previously expected to
be stable in flux on these time scales. Here we review these intriguing and
suggestive developments. In this context we give an overview of the
observational properties of the Crab and our current understanding of pulsars
and their nebulae.


title: Anomalous Fermi liquid phase in metallic Skyrmion crystals

abstract:
  In non-centrosymmetric crystals such as MnSi, magnetic order can take the
form of a skyrmion crystal (SkX) . In this phase, conduction electrons coupled
to the local magnetic moments acquire a Berry's phase, leading to an emergent
electromagnetism. Motivated by experimental reports of a non-Fermi liquid phase
in MnSi, in which resistivity is observed to scale as $\Delta \rho \sim
T^{3/2}$, here we examine the effect of coupling phonons of an incommensurate
SkX to electrons. Despite the formal similarity to a system consisting of a
Fermi surface coupled to an electromagnetic field, the Berry phase fluctuations
do not lead to non-Fermi liquid behavior. Instead, we propose a different
mechanism in which electrons scatter off columnar fluctuation in a
three-dimensional SkX. When the effects of lattice induced anisotropy are
neglected, these fluctuations are ultra-soft and induce an `anomalous Fermi
liquid' in which Landau quasiparticles survive but with an anomalous $\Delta
\rho(T)\sim T^{7/4}$ resistivity perpendicular to the columns, and a Fermi
liquid resistivity along them.

categories: cond-mat.str-el cond-mat.mes-hall cond-mat.other hep-ph


title: Finding Rare AGN: XMM-Newton and Chandra Observations of SDSS Stripe 82

abstract:
  We have analyzed the {\it XMM-Newton} and {\it Chandra} data overlapping
$\sim$16.5 deg$^2$ of Sloan Digital Sky Survey Stripe 82, including $\sim$4.6
deg$^2$ of proprietary {\it XMM-Newton} data that we present here. In total,
3362 unique X-ray sources are detected at high significance. We derive the {\it
XMM-Newton} number counts and compare them with our previously reported {\it
Chandra} Log$N$-Log$S$ relations and other X-ray surveys. The Stripe 82 X-ray
source lists have been matched to multi-wavelength catalogs using a maximum
likelihood estimator algorithm. We discovered the highest redshift ($z=5.86$)
quasar yet identified in an X-ray survey. We find 2.5 times more high
luminosity (L$_x \geq 10^{45}$ erg s$^{-1}$) AGN than the smaller area {\it
Chandra} and {\it XMM-Newton} survey of COSMOS and 1.3 times as many identified
by XBo\"otes. Comparing the high luminosity AGN we have identified with those
predicted by population synthesis models, our results suggest that this AGN
population is a more important component of cosmic black hole growth than
previously appreciated. Approximately a third of the X-ray sources not detected
in the optical are identified in the infrared, making them candidates for the
elusive population of obscured high luminosity AGN in the early universe.


title:
The Morphology and Dynamics of Jet-Driven Supernova Remnants: the Case
  of W49B

abstract:
  The circumstellar medium (CSM) of a massive star is modified by its winds
before a supernova (SN) explosion occurs, and thus the evolution of the
resulting supernova remnant (SNR) is influenced by both the geometry of the
explosion as well as the complex structure of the CSM. Motivated by recent work
suggesting the SNR W49B was a jet-driven SN expanding in a complex CSM, we
explore how the dynamics and the metal distributions in a jet-driven explosion
are modified by the interaction with the surrounding environment. In
particular, we perform hydrodynamical calculations to study the dynamics and
explosive nucleosynthesis of a jet-driven SN triggered by the collapse of a 25
solar masses Wolf-Rayet star and its subsequent interaction with the CSM up to
several hundred years following the explosion. We find that although the CSM
has small-scale effects on the structure of the SNR, the overall morphology and
abundance patterns are reflective of the initial asymmetry of the SN explosion.
Thus, we predict that jet-driven SNRs, such as W49B, should be identifiable
based on morphology and abundance patterns at ages up to several hundred years,
even if they expand into a complex CSM environment.


title:
Order-by-disorder and magnetic field response in Heisenberg-Kitaev model
  on a hyperhoneycomb lattice

abstract:
  We study the finite temperature phase diagram of the Heisenberg-Kitaev model
on a three dimensional hyperhoneycomb lattice. Using semiclassical analysis and
classical Monte-Carlo simulations, we investigate quantum and thermal
order-by-disorder, as well as the magnetic ordering temperature. We find the
parameter regime where quantum and thermal fluctuations favor different
magnetic orders, which leads to an additional finite temperature phase
transition within the ordered phase. This transition, however, occurs at a
relatively low temperature and the entropic effects may dominate most of the
finite temperature region below the ordering temperature. In addition, we
explore the magnetization process in the presence of a magnetic field and
discover spin-flop transitions which are sensitive to the applied-field
direction. We discuss implications of our results for future experiments on a
hyperhoneycomb lattice system such as the recently discovered \beta-Li2IrO3.


title: The Transition to the Metallic State in Low Density Hydrogen

abstract:
  Solid atomic hydrogen is one of the simplest systems to undergo a
metal-insulator transition. Near the transition, the electronic degrees of
freedom become strongly correlated and their description provides a difficult
challenge for theoretical methods. As a result, the order and density of the
phase transition are still subject to debate. In this work we use diffusion
quantum Monte Carlo to benchmark the transition between paramagnetic and
anti-ferromagnetic body centered cubic atomic hydrogen in its ground state. We
locate the density of the transition by computing the equation of state for
these two phases and identify the phase transition order by computing the band
gap near the phase transition. These benchmark results show that the phase
transition is continuous and occurs at a Wigner-Seitz radius of $r_s=2.27(3)
a_0$. We compare our results to previously reported density functional theory,
Hedin's GW approximation, and dynamical mean field theory results.


title:
The Influence of Differential Irradiation and Circulation on the Thermal
  Evolution of Gas Giant Planets. I. Upper Limits from Radiative Equilibrium

abstract:
  As a planet ages it cools and its radius shrinks, at a rate set by the
efficiency with which heat is transported from the interior out to space. The
bottleneck for this transport is at the boundary between the convective
interior and the radiative atmosphere; the opacity there sets the global
cooling rate. Models of planetary evolution are often one-dimensional, such
that the radiative-convective boundary (RCB) is defined by a single
temperature, pressure, and opacity. In reality the spatially inhomogenous
stellar heating pattern and circulation in the atmosphere could deform the RCB,
allowing heat from the interior to escape more efficiently through regions with
lower opacity. We present an analysis of the degree to which the RCB could be
deformed and the resultant change in the evolutionary cooling rate. In this
initial work we calculate the upper limit for this effect by comparing an
atmospheric structure in local radiative equilibrium to its 1D equivalent. We
find that the cooling through an uneven RCB could be enhanced over cooling
through a uniform RCB by as much as 10-50%. We also show that the deformation
of the RCB (and the enhancement of the cooling rate) increases with a greater
incident stellar flux or a lower inner entropy. Our results indicate that this
mechanism could significantly change a planet's thermal evolution, causing it
to cool and shrink more quickly than would otherwise be expected. This may
exacerbate the well known difficulty in explaining the very large radii
observed for some hot Jupiters.


title: Generalized quiver mutations and single-centered indices

abstract:
  Quiver quantum mechanics is invariant under Seiberg duality. A mathematical
consequence is that the cohomology of the Higgs branch moduli space is
invariant under mutations of the quiver. The Coulomb branch formula, on the
other hand, conjecturally expresses the Poincar\'e / Dolbeault polynomial of
the Higgs branch moduli space in terms of certain quantities known as
single-centered indices. In this work we determine the transformations of these
single-centered indices under mutations. Moreover, we generalize these
mutations to quivers whose nodes carry single-centered indices different from
unity. Although the Higgs branch description of these generalized quivers is
currently unknown, the Coulomb branch formula is conjectured to be invariant
under generalized mutations.


title:
The state of globular clusters at birth: emergence from the gas-embedded
  phase

abstract:
  In this paper, we discuss the origin of the observed correlation between
cluster concentration c and present-day mass function (PDMF) slope {\alpha}
reported by De Marchi, Paresce & Pulone. This relation can either be reproduced
from universal initial conditions combined with some dynamical mechanism(s)
that alter(s) the cluster structure and mass function over time, or it must
arise early on in the cluster lifetime, such as during the gas-embedded phase
of cluster formation. Using a combination of Monte Carlo and N-body models for
globular cluster evolution performed with the MOCCA and NBODY6 codes,
respectively, we explore a number of dynamical mechanisms that could affect the
observed relation.
  For the range of initial conditions considered here, our results are
consistent with an universal initial binary fraction \approx 10% (which does
not, however, preclude 100%) and an universal initial stellar mass function
resembling the standard Kroupa distribution. Most of the dispersion observed in
the c-{\alpha} relation can be attributed to two-body relaxation and Galactic
tides. However, dynamical processes alone could not have reproduced the
dispersion in concentration, and we require at least some correlation between
the initial concentration and the total cluster mass. We argue that the origin
of this trend could be connected to the gas-embedded phase of cluster
evolution.


title: Schmidt's Conjecture and Star Formation in Molecular Clouds

abstract:
  We investigate Schmidt's conjecture (i.e., that the star formation rate
scales in a power-law fashion with the gas density) for four well-studied local
molecular clouds (GMCs). Using the Bayesian methodology we show that a local
Schmidt scaling relation of the form Sigma*(A_K) = kappa x (A_K)^{beta}
(protostars pc^{-2}) exists within (but not between) GMCs. Further we find that
the Schmidt scaling law, by itself, does not provide an adequate description of
star formation activity in GMCs. Because the total number of protostars
produced by a cloud is given by the product of Sigma*(A_K) and S'(> A_K), the
differential surface area distribution function, integrated over the entire
cloud, the cloud's structure plays a fundamental role in setting the level of
its star formation activity. For clouds with similar functional forms of
Sigma*(A_K), observed differences in their total SFRs are primarily due to the
differences in S'(> A_K) between the clouds. The coupling of Sigma*(A_K) with
the measured S'(> A_K) in these clouds also produces a steep jump in the SFR
and protostellar production above A_K ~ 0.8 magnitudes. Finally, we show that
there is no global Schmidt law that relates the star formation rate and gas
mass surface densities between GMCs. Consequently, the observed
Kennicutt-Schmidt scaling relation for disk galaxies is likely an artifact of
unresolved measurements of GMCs and not a result of any underlying physical law
of star formation characterizing the molecular gas.


title:
Reionization on Large Scales IV: Predictions for the 21 cm signal
  incorporating the light cone effect

abstract:
  We present predictions for the 21 cm brightness temperature power spectrum
during the Epoch of Reionization (EoR). We discuss the implications of the
"light cone" effect, which incorporates evolution of the neutral hydrogen
fraction and 21 cm brightness temperature along the line of sight. Using a
novel method calibrated against radiation-hydrodynamic simulations, we model
the neutral hydrogen density field and 21 cm signal in large volumes ($L = 2$
Gpc/$h$). The inclusion of the light cone effect leads to a relative decrease
of about 50% in the 21 cm power spectrum on all scales. We also find that the
effect is more prominent at the midpoint of reionization and later. The light
cone effect also can introduce an anisotropy along the line of sight. By
decomposing the 3D power spectrum into components perpendicular to and along
the line of sight, we find that in our fiducial reionization model, there is no
significant anisotropy. However, parallel modes can contribute up to 40% more
power for shorter reionization scenarios. The scales on which the light cone
effect is relevant are comparable to scales where one measures the baryon
acoustic oscillation. We argue that due to its large comoving scale and
introduction of anisotropy, the light cone effect is important when considering
redshift space distortions and future application to the Alcock-Paczynski test
for the determination of cosmological parameters.


title:
A new model of galaxy formation: How sensitive are predicted galaxy
  luminosities to the choice of SPS model?

abstract:
  We present a new release of the GALFORM semi-analytical model of galaxy
formation and evolution, which exploits a Millennium Simulation-class N-body
run performed with the WMAP7 cosmology. We use this new model to study the
impact of the choice of stellar population synthesis (SPS) model on the
predicted evolution of the galaxy luminosity function. The semi-analytical
model is run using seven different SPS models. In each case we obtain the
rest-frame luminosity function in the far-ultra-violet, optical and
near-infrared (NIR) wavelength ranges. We find that both the predicted
rest-frame ultra-violet and optical luminosity function are insensitive to the
choice of SPS model. However, we find that the predicted evolution of the
rest-frame NIR luminosity function depends strongly on the treatment of the
thermally pulsating asymptotic giant branch (TP-AGB) stellar phase in the SPS
models, with differences larger than a factor of 2 for model galaxies brighter
than $M_{\rm AB}(K)-5$log$h<-22$ ($\sim$L$_*$ for $0\leq z\leq 1.5$). We have
also explored the predicted number counts of galaxies, finding remarkable
agreement between the results with different choices of SPS model, except when
selecting galaxies with very red optical-NIR colours. The predicted number
counts of these extremely red galaxies appear to be more affected by the
treatment of star formation in disks than by the treatment of TP-AGB stars in
the SPS models.


title: Metals and ionizing photons from dwarf galaxies

abstract:
  We estimate the potential contribution of M < 10^9 Msun dwarf galaxies to the
reionization and early metal-enrichment of the Milky Way environment, or
circum-Galactic Medium. Our approach is to use the observed properties of
ancient stars (> 12 Gyr old) measured in nearby dwarf galaxies to characterize
the star-formation at high-z. We use a merger-tree model for the build-up of
the Milky Way, which self-consistently accounts for feedback processes, and
which is calibrated to match the present-day properties of the Galaxy and its
dwarf satellites. We show that the high-z analogues of nearby dwarf galaxies
can produce the bulk of ionizing radiation (>80%) required to reionize the
Milky Way environment. Our fiducial model shows that the gaseous environment
can be 50% reionized at z ~ 8 by galaxies with 10^7 Msun < M < 10^8 Msun. At
later times, radiative feedback stops the star-formation in these small
systems, and reionization is completed by more massive dwarf galaxies by z_rei
= 6.4\pm 0.5. The metals ejected by supernova-driven outflows from M < 10^9
Msun dwarf galaxies almost uniformly fill the Milky Way environment by z ~ 5,
enriching it to Z ~ 2 10^-2 Zsun. At z ~ 2 these early metals are still found
to represent ~ 50% of the total mass of heavy elements in the circum-Galactic
Medium.


title: Merging Tree Algorithm of Growing Voids in Self Similar and CDM Models

abstract:
  Observational studies show that voids are prominent features of the large
scale structure of the present day Universe. Even though their emerging from
the primordial density perturbations and evolutionary patterns differ from dark
matter halos, N-body simulations and theoretical models have shown that voids
also merge together to form large void structures. In this study, following
Sheth & van de Weygaert (2004), we formulate an analytical approximate
description of the hierarchical void evolution of growing voids by adopting the
halo merging algorithm given by Lacey & Cole (1993) in the Einstein de Sitter
(EdS) Universe. To do this, we take into account the general volume
distribution of voids which consists of two main void processes: merging and
collapsing. We show that the volume distribution function can be reduced to a
simple form, by neglecting the collapsing void contribution since the collapse
process is negligible for large size voids. Therefore, the void volume fraction
has a contribution only from growing voids. This algorithm becomes the analogue
of the halo merging algorithm. Based on this growing void distribution, we
obtain the void merging algorithm in which we define and formulate void merging
and absorption rates, as well as void size and redshift survival probabilities
and also failure rates in terms of the self similar and currently favored dark
energy dominated cold dark matter models in the EdS Universe.


title: Asymptotic Properties of Unbounded Quadrature Domains in the Plane

abstract:
  We prove that if $\Omega$ is a simply connected quadrature domain for a
distribution with compact support and the infinity point belongs the boundary,
then the boundary has an asymptotic curve that is either a straight line or a
parabola or an infinite ray. In other words, unbounded quadrature domains in
the plane are perturbations of null quadrature domains.


title:
The Environment around the Young Massive Star Cluster RSGC 1 and HESS
  J1837-069

abstract:
  We report on Mopra observations toward the young massive star cluster RSGC 1,
adjoined by, and possibly associated with the gamma-ray source HESS J1837-069.
We measure the CO (J=1-0) distribution around the cluster and gamma-ray source,
and find that the cluster is slightly higher than the velocity ranges
associated with the Crux-Scutum arm. We reveal the cluster is associated with
much less molecular gas compared with other young massive clusters in the
Galaxy, Westerlund 1 (Wd 1) and 2 (Wd 2), which also radiate gamma-rays. We
find no other structures that would otherwise indicate the action of supernova
remnants, and due to the lack of material which may form gamma-rays by hadronic
interaction, we conclude that the gamma-rays detected from HESS J1837-069 are
not created through proton-proton interactions, and may more plausibly
originate from the pulsar that was recently found near RSGC 1.


title: Fibre bundle framework for unitary quantum fault tolerance

abstract:
  We introduce a differential geometric framework for describing families of
quantum error-correcting codes and for understanding quantum fault tolerance.
This work unifies the notion of topological fault tolerance with fault
tolerance in other kinds of quantum error-correcting codes. In particular, we
use fibre bundles with a natural flat projective connection to study the
transformation of codewords under unitary fault-tolerant evolutions. We show
that the fault-tolerant logical operations are given by the monodromy group for
either of two bundles, both of which have flat projective connections. As
concrete realizations of the general framework, we construct the bundles
explicitly for two examples of fault-tolerant families of operations, the qudit
transversal gates and the string operators in the toric code.

categories: quant-ph math-ph math.DG math.GT math.MP


title: Social Business Transformation through Gamification

abstract:
  Being an emerging business practice, gamification is going to the mainstream
to enable and transform social business initiatives across enterprises. With
the consistent focus on customer behavior and experience, there is a paradigm
shift in thinking about how Gamification and Social initiatives together help
to increase the engagement level of knowledge worker, yielding better business
results. Business scenarios for gamification are wide spread ranging from
customer service and support to communities and collaboration.
  The Paper discusses the characteristics & mechanism to learn from games that
are important for businesses to understand and apply. It also gives insights on
gamification trends, real-world business challenges and also describes on how
game thinking can revolutionize the business and create an engaging experience.


title: Stable Intersections of Tropical Varieties

abstract:
  We give several characterizations of stable intersections of tropical cycles
and establish their fundamental properties. We prove that the stable
intersection of two tropical varieties is the tropicalization of the
intersection of the classical varieties after a generic rescaling. A proof of
Bernstein's theorem follows from this. We prove that the tropical intersection
ring of tropical cycle fans is isomorphic to McMullen's polytope algebra. It
follows that every tropical cycle fan is a linear combination of pure powers of
tropical hypersurfaces, which are always realizable. We prove that every stable
intersection of constant coefficient tropical varieties defined by prime ideals
is connected through codimension one. We also give an example of a realizable
tropical variety that is connected through codimension one but whose stable
intersection with a hyperplane is not.


title:
Non-Landau damping of magnetic excitations in systems with localized and
  itinerant electrons

abstract:
  We discuss the form of the damping of magnetic excitations in a metal near a
ferromagnetic instability. The paramagnon theory predicts that the damping term
should have the form $\Omega/\Gamma (q)$ with $\Gamma (q) \propto q$ (the
Landau damping). However, the experiments on uranium metallic compounds UGe$_2$
and UCoGe showed that $\Gamma (q)$ tends to a constant value at vanishing $q$.
A non-zero $\Gamma (0)$ is impossible in systems with one type of carriers
(either localized or itinerant) because it would violate the spin conservation.
It has been conjectured recently that a non-zero $\Gamma (q)$ in UGe$_2$ and
UCoGe may be due to the presence of both localized and itinerant electrons in
these materials, with ferromagnetism involving predominantly localized spins.
We present microscopic analysis of the damping of near-critical localized
excitations due to interaction with itinerant carriers. We show explicitly how
the presence of two types of electrons breaks the cancellation between the
contributions to $\Gamma (0)$ from self-energy and vertex correction insertions
into the spin polarization bubble and discuss the special role of the
Aslamazov-Larkin processes. We show that $\Gamma (0)$ increases with $T$ both
in the paramagnetic and ferromagnetic regions, but in-between it has a peak at
$T_c$. We compare our theory with the available experimental data.


title: High Throughput Data Center Topology Design

abstract:
  With high throughput networks acquiring a crucial role in supporting
data-intensive applications, a variety of data center network topologies have
been proposed to achieve high capacity at low cost. While this literature
explores a large number of design points, even in the limited case of a network
of identical switches, no proposal has been able to claim any notion of
optimality. The case of heterogeneous networks, incorporating multiple
line-speeds and port-counts as data centers grow over time, introduces even
greater complexity.
  In this paper, we present the first non-trivial upper-bound on network
throughput under uniform traffic patterns for any topology with identical
switches. We then show that random graphs achieve throughput surprisingly close
to this bound, within a few percent at the scale of a few thousand servers.
Apart from demonstrating that homogeneous topology design may be reaching its
limits, this result also motivates our use of random graphs as building blocks
to explore the design of heterogeneous networks. Given a heterogeneous pool of
network switches, through experiments and analysis, we explore how the
distribution of servers across switches and the interconnection of switches
affect network throughput. We apply these insights to a real-world
heterogeneous data center topology, VL2, demonstrating as much as 43% higher
throughput with the same equipment.


title: The Sasaki Join, Hamiltonian 2-forms, and Sasaki-Einstein Metrics

abstract:
  By combining the join construction from Sasakian geometry with the
Hamiltonian 2-form construction from K\"ahler geometry, we recover
Sasaki-Einstein metrics discovered by physicists. Our geometrical approach
allows us to give an algorithm for computing the topology of these
Sasaki-Einstein manifolds. In particular, we explicitly compute the cohomology
rings for several cases of interest and give a formula for homotopy equivalence
in one particular 7-dimensional case. We also show that our construction gives
at least a two dimensional cone of both Sasaki-Ricci solitons and extremal
Sasaki metrics.


title: Investigation of commuting Hamiltonian in quantum Markov network

abstract:
  Graphical Models have various applications in science and engineering which
include physics, bioinformatics, telecommunication and etc. Usage of graphical
models needs complex computations in order to evaluation of marginal
functions,so there are some powerful methods including mean field
approximation, belief propagation algorithm and etc. Quantum graphical models
have been recently developed in context of quantum information and computation,
and quantum statistical physics, which is possible by generalization of
classical probability theory to quantum theory. The main goal of this paper is
preparing a primary generalization of Markov network, as a type of graphical
models, to quantum case and applying in quantum statistical physics.We have
investigated the Markov network and the role of commuting Hamiltonian terms in
conditional independence with simple examples of quantum statistical physics.


title: Partial cohomology of groups

abstract:
  We develop a cohomology theory of groups based on partial actions and explore
its relation with the partial Schur multiplier as well as with cohomology of
inverse semigroups.


title: How (not) to teach Lorentz covariance of the Dirac equation

abstract:
  In the textbook proofs of Lorentz covariance of the Dirac equation, one
treats the wave function as a spinor and gamma matrices as scalars, leading to
a quite complicated formalism with several pedagogic drawbacks. As an
alternative, I propose to teach Dirac equation and its Lorentz covariance by
using a much simpler, but physically equivalent formalism, in which these
drawbacks do not appear. In this alternative formalism, the wave function
transforms as a scalar and gamma matrices as components of a vector, such that
the standard physically relevant bilinear combinations do not change their
transformation properties. The alternative formalism allows also a natural
construction of some additional non-standard bilinear combinations with
well-defined transformation properties.