title: Spin relaxation in ultracold spin-orbit coupled $^{40}$K gas

abstract:
  We report the anomalous Dyakonov-Perel' spin relaxation in ultracold
spin-orbit coupled $^{40}$K gas when the coupling between $|9/2,9/2\ >$ and
$|9/2,7/2\ >$ states (atcing as the effective Zeeman magnetic field) is much
stronger than the spin-orbit coupled field. Both the transverse and
longitudinal spin relaxations are investigated with small and large spin
polarizations. It is found that with small spin polarization, the transverse
(longitudinal) spin relaxation is divided into four (two) regimes: the normal
weak scattering regime, the anomalous Dyakonov-Perel'-like regime, the
anomalous Elliott-Yafet-like regime and the normal strong scattering regime
(the anomalous Elliott-Yafet-like regime and the normal strong scattering
regime), with only the normal weak scattering regime being in the weak
scattering limit. This is very different from the conventional situation under
the weak magnetic field, which is divided into the weak and strong scattering
regimes according to the weak/strong scattering limit. With large spin
polarization, we find that the Hartree-Fock self-energy, which acts as an
effective magnetic field, can markedly suppress the transverse spin relaxation
in both weak and strong scattering limits. Moreover, by noting that as both the
momentum relaxation time and the Hartree-Fock effective magnetic field vary
with the scattering length in cold atoms, the anomalous Dyakonov-Perel'-like
regime is suppressed and the transverse spin relaxation is hence divided into
three regimes in the scattering length dependence: the normal weak scattering
regime, the anomalous Elliott-Yafet-like regime and the strong scattering
regime. On the other hand, the longitudinal spin relaxation is again divided
into the anomalous EY-like and normal strong scattering regimes. ...


title:
Eavesdropping time and frequency: phase noise cancellation along a
  time-varying path, such as an optical fiber

abstract:
  Single-mode optical fiber is a highly efficient connecting medium, used not
only for optical telecommunications but also for the dissemination of
ultra-stable frequencies or timing signals. In 1994, Ma, Jungner, Ye and Hall
described a measurement and control system to deliver the same optical
frequency at two places, namely the two ends of a fiber, by eliminating the
"fiber-induced phase-noise modulation, which corrupts high-precision
frequency-based applications". We present a simple detection and control scheme
to deliver the same optical frequency at many places anywhere along a
transmission path, or in its vicinity, with a relative instability of 1 part in
$10^{19}$. The same idea applies to radio frequency and timing signals. This
considerably simplifies future efforts to make precise timing/frequency signals
available to many users, as required in some large scale science experiments.


title:
Verification of first-principles codes: comparison of total energies,
  phonon frequencies, electron-phonon coupling and zero-point motion correction
  to the gap between ABINIT and QE/Yambo

abstract:
  With the ever-increasing sophistication of codes, the verification of the
implementation of advanced theoretical formalisms becomes critical. In
particular, cross comparison between different codes provides a strong hint in
favor of the correctness of the implementations, and a measure of the
(hopefully small) possible numerical differences. We lead a rigorous and
careful study of the quantities that enter in the calculation of the zero-point
motion renormalization of the direct band gap of diamond due to electron-phonon
coupling, starting from the total energy, and going through the computation of
phonon frequencies and electron-phonon matrix elements. We rely on two
independent implementations : Quantum Espresso + Yambo and ABINIT. We provide
the order of magnitude of the numerical discrepancies between the codes, that
are present for the different quantities: less than $10^{-5}$ Hartree per atom
on the total energy (-5.722 Ha/at), less than 0.07 cm$^{-1}$ on the
$\Gamma,L,X$ phonon frequencies (555 to 1330 cm$^{-1}$), less than 0.5% on the
square of the electron-phonon matrix elements and less than 4 meV on the
zero-point motion renormalization of each eigenenergies (44 to 264 meV). Within
our approximations, the DFT converged direct band gap renormalization in
diamond due to the electron-phonon coupling is -0.409 eV (reduction of the band
gap).


title:
Valence quark and meson cloud contributions to the $\gamma^\ast N \to
  N^\ast(1520)$ form factors

abstract:
  The covariant spectator quark model is applied to the $\gamma^\ast N \to
N^\ast(1520)$ reaction. The valence quark contributions to the electromagnetic
form factors and helicity transition amplitudes are estimated from the
covariant structure of the $N^\ast(1520)$ wave function calibrated by the
experimental data for large squared momentum transfer $Q^2$. The difference
between the model results and the experimental data is then used to
parameterize the low $Q^2$ behavior, where meson cloud effects are assumed to
dominate. This parametrization can be very useful for future studies of the
reaction, as well as for the extension of the transition form factors to the
timelike region.


title:
One Possible Reason for Double-Peaked Maxima in Solar Cycles: Is a
  Second Maximum of Solar Cycle 24 Coming?

abstract:
  We investigate solar activity by focusing on double maxima in solar cycles
and try to estimate the shape of the current solar cycle (Cycle 24) during its
maximum. We analyzed data for Solar Cycle 24 by using Learmonth Solar
Observatory sunspot group data since 2008. All sunspot groups (SGs) recorded
during this time interval were separated into two groups: The first group
includes small SGs [A, B, C, H, classes by the Zurich classification], and the
second group consists of large SGs [D, E, and F]. We then calculated small and
large sunspot group numbers, their sunspot numbers [SSN] and Zurich numbers
[Rz] from their daily mean numbers as observed on the solar disk during a given
month. We found that the temporal variations for these three different
separations behave similarly. We also analyzed the general shape of solar
cycles from Cycle 1 to 23 by using monthly International Sunspot Number [ISSN]
data and found that the durations of maxima were about 2.9 years. Finally, we
used ascending time and SSN relationship and found that the maximum of the
Cycle 24 should be later than 2011. Thus, we conclude that i) one possible
reason for a double maximum in solar cycles is the different behavior of large
and small sunspot groups, and ii) a double maximum is coming for Solar Cycle
24.


title:
Creation and revival of ring dark solitons in a toroidal Bose-Einstein
  condensate

abstract:
  We propose a protocol for the simultaneous controlled creation of multiple
concentric ring dark solitons in a toroidally trapped Bose-Einstein condensate.
The decay of these solitons into a vortex-antivortex necklace shows revivals of
the soliton structure, but eventually becomes an example of quantum turbulence.


title: The Fixed Points of the Multivariate Smoothing Transform

abstract:
  Let $N,d > 1$ be fixed integers, let $(T_1, ..., T_N)$ be random d-by-d
matrices with nonnegative entries and $Q$ a random d-vector with nonnegative
entries. This induces a mapping (the multivariate smoothing transform) on
probability laws on the nonnegative cone by $S \eta := \mathrm{Law\ of}\ (T_1
X_1 + ... + T_N X_N + Q)$, where the $X_i$ are iid with law $\eta$ and
independent of $(T_1, ..., T_N, Q)$. Under conditions similar to those for the
well-studied case d=1, a complete characterization of all fixed points of $S$
is obtained.


title:
Developing Tutorials for Advanced Physics Students: Processes and
  Lessons Learned

abstract:
  When education researchers describe newly developed curricular materials,
they typically concentrate on the research base behind their design, and the
efficacy of the final products, but do not highlight the initial stages of
creating the actual materials. With the aim of providing useful information for
faculty engaged in similar projects, we describe here our development of a set
of in-class tutorials for advanced undergraduate electrodynamics students, and
discuss factors that influenced their initial design and refinement. Among the
obstacles to be overcome was the investigation of student difficulties within
the short time frame of our project, and devising ways for students to engage
in meaningful activities on advanced-level topics within a single 50-minute
class period. We argue for a process that leverages faculty experience and
classroom observations, and present several guidelines for tutorial development
and implementation in upper-division physics classrooms.


title:
Tracing magnetic separators and their dependence on IMF clock angle in
  global magnetospheric simulations

abstract:
  A new, efficient, and highly accurate method for tracing magnetic separators
in global magnetospheric simulations with arbitrary clock angle is presented.
The technique is to begin at a magnetic null and iteratively march along the
separator by finding where four magnetic topologies meet on a spherical
surface. The technique is verified using exact solutions for separators
resulting from an analytic magnetic field model that superposes dipolar and
uniform magnetic fields. Global resistive magnetohydrodynamic simulations are
performed using the three-dimensional BATS-R-US code with a uniform
resistivity, in eight distinct simulations with interplanetary magnetic field
(IMF) clock angles ranging from 0 (parallel) to 180 degrees (anti-parallel).
Magnetic nulls and separators are found in the simulations, and it is shown
that separators traced here are accurate for any clock angle, unlike the last
closed field line on the Sun-Earth line that fails for southward IMF. Trends in
magnetic null locations and the structure of magnetic separators as a function
of clock angle are presented and compared with those from the analytic field
model. There are many qualitative similarities between the two models, but
quantitative differences are also noted. Dependence on solar wind density is
briefly investigated.


title:
Swift J053041.9-665426, a new Be/X-ray binary pulsar in the Large
  Magellanic Cloud

abstract:
  We observed the newly discovered X-ray source Swift J053041.9-665426 in the
X-ray and optical regime to confirm its proposed nature as a high mass X-ray
binary. We obtained XMM-Newton and Swift X-ray data, along with optical
observations with the ESO Faint Object Spectrograph, to investigate the
spectral and temporal characteristics of Swift J053041.9-665426. The XMM-Newton
data show coherent X-ray pulsations with a period of 28.77521(10) s (1 sigma).
The X-ray spectrum can be modelled by an absorbed power law with photon index
within the range 0.76 to 0.87. The addition of a black body component increases
the quality of the fit but also leads to strong dependences of the photon
index, black-body temperature and absorption column density. We identified the
only optical counterpart within the error circle of XMM-Newton at an angular
distance of ~0.8 arcsec, which is 2MASS J05304215-6654303. We performed optical
spectroscopy from which we classify the companion as a B0-1.5Ve star. The X-ray
pulsations and long-term variability, as well as the properties of the optical
counterpart, confirm that Swift J053041.9-665426 is a new Be/X-ray binary
pulsar in the Large Magellanic Cloud.


title:
Monitoring young associations and open clusters with Kepler in two-wheel
  mode

abstract:
  We outline a proposal to use the Kepler spacecraft in two-wheel mode to
monitor a handful of young associations and open clusters, for a few weeks
each. Judging from the experience of similar projects using ground-based
telescopes and the CoRoT spacecraft, this program would transform our
understanding of early stellar evolution through the study of pulsations,
rotation, activity, the detection and characterisation of eclipsing binaries,
and the possible detection of transiting exoplanets. Importantly, Kepler's wide
field-of-view would enable key spatially extended, nearby regions to be
monitored in their entirety for the first time, and the proposed observations
would exploit unique synergies with the GAIA ESO spectroscopic survey and, in
the longer term, the GAIA mission itself. We also outline possible strategies
for optimising the photometric performance of Kepler in two-wheel mode by
modelling pixel sensitivity variations and other systematics.


title: Multiparton Interactions and Double Parton Scatterings in CMS

abstract:
  Multiparton interactions are introduced in order to explain a wide range of
phenomena in p-p collisions. We present the most recent CMS measurements
sensitive to multiparton interactions and hard double parton scattering at 7
TeV. In particular, the W+dijet channel and a scenario with four light jets in
the final state are described.


title: Inhomogeneous Spatially Dispersive Electromagnetic Media

abstract:
  Two key types of inhomogeneous spatially dispersive media are described, both
based on a spatially dispersive generalisation of the single resonance model of
permittivity. The boundary conditions for two such media with different
properties are investigated using Lagrangian and distributional methods. Wave
packet solutions to Maxwell's equations, where the permittivity varies and is
periodic in the medium, are then found.


title:
The Kep-Cont Mission: Continuing the observation of high-amplitude
  variable stars in the Kepler field of view

abstract:
  As a response to the Kepler white paper call, we propose to keep Kepler
pointing to its current field of view and continue observing thousands of large
amplitude variables (Cepheid, RR Lyrae and delta Scuti stars among others) with
high cadence in the Kep-Cont Mission. The degraded pointing stability will
still allow observation of these stars with reasonable (better than millimag)
precision. The Kep-Cont mission will allow studying the nonradial modes in
Blazhko-modulated and first overtone RR Lyrae stars and will give a better view
on the period jitter of the only Kepler Cepheid in the field. With continued
continuous observation of the Kepler RR Lyrae sample we may get closer to the
origin of the century-old Blazhko problem. Longer time-span may also uncover
new dynamical effects like apsidal motion in eclipsing binaries. A continued
mission will have the advantage of providing unprecedented, many-years-long
homogeneous and continuous photometric data of the same targets. We investigate
the pragmatic details of such a mission and find a number of advantages,
especially the minimal need of reprogramming of the flight software. Another
undeniable advantage of the current field of view is the completed, ongoing and
planned ground-based follow-up observations and allocated telescope times
focusing on the current field. We emphasize that while we propose this
continuation as an independent mission, we can easily share slots with e.g.
planetary mission with a strong belief that both (or more) communities can
still benefit from Kepler's current capabilities.


title:
The Kepler-SEP Mission: Harvesting the South Ecliptic Pole
  large-amplitude variables with Kepler

abstract:
  As a response to the white paper call, we propose to turn Kepler to the South
Ecliptic Pole (SEP) and observe thousands of large amplitude variables for
years with high cadence in the frame of the Kepler-SEP Mission. The degraded
pointing stability will still allow observing these stars with reasonable
(probably better than mmag) accuracy. Long-term continuous monitoring already
proved to be extremely helpful to investigate several areas of stellar
astrophysics. Space-based missions opened a new window to the dynamics of
pulsation in several class of pulsating variable stars and facilitated detailed
studies of eclipsing binaries. The main aim of this mission is to better
understand the fascinating dynamics behind various stellar pulsational
phenomena (resonances, mode coupling, chaos, mode selection) and interior
physics (turbulent convection, opacities). This will also improve the
applicability of these astrophysical tools for distance measurements,
population and stellar evolution studies. We investigated the pragmatic details
of such a mission and found a number of advantages: minimal reprogramming of
the flight software, a favorable field of view, access to both galactic and LMC
objects. However, the main advantage of the SEP field comes from the large
sample of well classified targets, mainly through OGLE. Synergies and
significant overlap (spatial, temporal and in brightness) with both ground-
(OGLE, LSST) and space-based missions (GAIA, TESS) will greatly enhance the
scientific value of the Kepler-SEP mission. GAIA will allow full
characterization of the distance indicators. TESS will continuously monitor
this field for at least one year, and together with the proposed mission
provide long time series that cannot be obtained by other means. If Kepler-SEP
program is successful, there is a possibility to place one of the so-called
LSST "deep-drilling" fields in this region.


title: Perpendicular Ion Heating by Reduced Magnetohydrodynamic Turbulence

abstract:
  Recent theoretical studies argue that the rate of stochastic ion heating in
low-frequency Alfv\'en-wave turbulence is given by $Q_\perp = c_1 [(\delta u)^3
/\rho] \exp(-c_2/\epsilon)$, where $\delta u$ is the rms turbulent velocity at
the scale of the ion gyroradius $\rho$, $\epsilon = \delta u/v_{\perp \rm i}$,
$v_{\perp \rm i}$ is the perpendicular ion thermal speed, and $c_1$ and $c_2$
are dimensionless constants. We test this theoretical result by numerically
simulating test particles interacting with strong reduced magnetohydrodynamic
(RMHD) turbulence. The heating rates in our simulations are well fit by this
formula. The best-fit values of $c_1$ are $\sim 1$. The best-fit values of
$c_2$ decrease (i.e., stochastic heating becomes more effective) as the grid
size and Reynolds number of the RMHD simulations increase. As an example, in a
$1024^2 \times 256$ RMHD simulation with a dissipation wavenumber of order the
inverse ion gyroradius, we find $c_2 = 0.21$. We show that stochastic heating
is significantly stronger in strong RMHD turbulence than in a field of randomly
phased Alfv\'en waves with the same power spectrum, because coherent structures
in strong RMHD turbulence increase orbit stochasticity in the regions where
ions are heated most strongly. We find that $c_1$ increases by a factor of
$\sim 3$ while $c_2$ changes very little as the ion thermal speed increases
from values $\ll v_{\rm A}$ to values $\sim v_{\rm A}$, where $v_{\rm A}$ is
the Alfv\'en speed. We discuss the importance of these results for
perpendicular ion heating in the solar wind.


title: Triangulations with few ears: symmetry classes and disjointness

abstract:
  An ear in a triangulation $T$ of a convex $n$-gon $P$ is a triangle of $T$
that shares two sides with $P$ itself. Certain enumerational and structural
problems become easier when one considers only triangulations with few ears. We
demonstrate this in two ways. First, for $k=2, 3$, we find the number of
symmetry classes of triangulations with $k$ ears. Second, for $k=2, 3$, we
determine the number of triangulations disjoint from a given triangulation:
this number depends only on $n$ for $k=2$, and only on lengths of branches of
the dual tree for $k=3$.


title: On Squares in Lucas Sequences

abstract:
  In this short paper, we prove, by only using elementary tools, general cases
when $U_n(P,Q) \neq \square$, where $U_n(P,Q)$ is the Lucas sequence of the
first type.


title:
From the Physics of Interacting Polymers to Optimizing Routes on the
  London Underground

abstract:
  Optimizing paths on networks is crucial for many applications, from subway
traffic to Internet communication. As global path optimization that takes
account of all path-choices simultaneously is computationally hard, most
existing routing algorithms optimize paths individually, thus providing
sub-optimal solutions. We employ the physics of interacting polymers and
disordered systems to analyze macroscopic properties of generic
path-optimization problems and derive a simple, principled, generic and
distributed routing algorithm capable of considering simultaneously all
individual path choices. We demonstrate the efficacy of the new algorithm by
applying it to: (i) random graphs resembling Internet overlay networks; (ii)
travel on the London underground network based on Oyster-card data; and (iii)
the global airport network. Analytically derived macroscopic properties give
rise to insightful new routing phenomena, including phase transitions and
scaling laws, which facilitate better understanding of the appropriate
operational regimes and their limitations that are difficult to obtain
otherwise.

categories: physics.soc-ph cond-mat.dis-nn cond-mat.stat-mech cs.NI nlin.AO


title: ${\cal PT}$-symmetric coupler with $\chi^{(2)}$ nonlinearity

abstract:
  We introduce the notion of a ${\cal PT}$-symmetric dimer with a $\chi^{(2)}$
nonlinearity. Similarly to the Kerr case, we argue that such a nonlinearity
should be accessible in a pair of optical waveguides with quadratic
nonlinearity and gain and loss, respectively. An interesting feature of the
problem is that because of the two harmonics, there exist in general two
distinct gain/loss parameters, different values of which are considered herein.
We find a number of traits that appear to be absent in the more standard cubic
case. For instance, bifurcations of nonlinear modes from the linear solutions
occur in two different ways depending on whether the first or the second
harmonic amplitude is vanishing in the underlying linear eigenvector. Moreover,
a host of interesting bifurcation phenomena appear to occur including
saddle-center and pitchfork bifurcations which our parametric variations
elucidate. The existence and stability analysis of the stationary solutions is
corroborated by numerical time-evolution simulations exploring the evolution of
the different configurations, when unstable.


title:
On the equivalence between coarse and uniform embeddability of
  quasi-Banach spaces into a Hilbert space

abstract:
  We give a direct proof of the fact that a quasi-Banach space coarsely embeds
into a Hilbert space if and only if it uniformly embeds into a Hilbert space.


title:
Wave front adaptation using a deformable mirror for adiabatic
  nanofocusing along an ultrasharp gold taper

abstract:
  We describe and demonstrate the use of an adaptive wave front optimization
scheme for enhancing the efficiency of adiabatic nanofocusing of surface
plasmon polariton (SPP) waves along an ultrasharp conical gold taper. Adiabatic
nanofocusing is an emerging and promising scheme for controlled focusing of far
field light into nanometric volumes. It comprises three essential steps: SPP
excitation by coupling far field light to an SPP waveguide, SPP propagation
along the waveguide and adiabatic SPP nanofocusing towards a geometric
singularity. For commonly used complex waveguide geometries, such as, e.g.,
conical metal tapers, a realistic modeling and efficiency optimization is
challenging. Here, we use a deformable mirror to adaptively control the wave
front of the incident far field light. We demonstrate an eight-fold enhancement
in nanofocusing efficiency and analyze the shape of the resulting optimized
wave front. The introduced wave front optimization scheme is of general
interest for guiding and controlling light on the nanoscale.


title:
Exact Stochastic Unraveling of an Optical Coherence Dynamics by Cumulant
  Expansion

abstract:
  A numerically exact Monte Carlo scheme for calculation of open quantum system
dynamics is proposed and implemented. The method consists of a Monte-Carlo
summation of a perturbation expansion in terms of trajectories in Liouville
phase-space with respect to the coupling between the excited states of the
molecule. The trajectories are weighted by a complex decoherence factor based
on the second-order cumulant expansion of the environmental evolution. The
method can be used with an arbitrary environment characterized by a general
correlation function and arbitrary coupling strength. It is formally exact for
harmonic environments, and it can be used with arbitrary temperature. Time
evolution of an optically excited Frenkel exciton dimer representing a
molecular exciton interacting with a charge transfer state is calculated by the
proposed method. We calculate the evolution of the optical coherence elements
of the density matrix and linear absorption spectrum, and compare them with the
predictions of standard simulation methods.


title:
Application of Expurgated PPM to Indoor Visible Light Communications -
  Part I: Single-User Systems

abstract:
  Visible light communications (VLC) in indoor environments suffer from the
limited bandwidth of LEDs as well as from the inter-symbol interference (ISI)
imposed by multipath. In this work, transmission schemes to improve the
performance of indoor optical wireless communication (OWC) systems are
introduced. Expurgated pulse-position modulation (EPPM) is proposed for this
application since it can provide a wide range of peak to average power ratios
(PAPR) needed for dimming of the indoor illumination. A correlation decoder
used at the receiver is shown to be optimal for indoor VLC systems, which are
shot noise and background-light limited. Interleaving applied on EPPM in order
to decrease the ISI effect in dispersive VLC channels can significantly
decrease the error probability. The proposed interleaving technique makes EPPM
a better modulation option compared to PPM for VLC systems or any other
dispersive OWC system. An overlapped EPPM pulse technique is proposed to
increase the transmission rate when bandwidth-limited white LEDs are used as
sources.


title: Laurent Phenomenon Sequences

abstract:
  In this paper, we undertake a systematic study of recurrences x_{m+n}x_{m} =
P(x_{m+1}, ..., x_{m+n-1}) which exhibit the Laurent phenomenon. Some of the
most famous among these sequences come from the Somos and the Gale-Robinson
recurrences. Our approach is based on finding period 1 seeds of Laurent
phenomenon algebras of Lam-Pylyavskyy. We completely classify polynomials P
that generate period 1 seeds in the cases of n=2,3 and of mutual binomial
seeds. We also find several other interesting families of polynomials P whose
generated sequences exhibit the Laurent phenomenon. Our classification for
binomial seeds is a direct generalization of a result by Fordy and Marsh, that
employs a new combinatorial gadget we call a double quiver.


title:
AID: An Energy Efficient Decoding Scheme for LDPC Codes in Wireless Body
  Area Sensor Networks

abstract:
  One of the major challenges in Wireless Body Area Networks (WBANs) is to
prolong the lifetime of network. Traditional research work focuses on
minimizing transmit power, however, in the case of short range communication
the consumption power in decoding is significantly larger than transmit power.
This paper investigates the minimization of total power consumption by reducing
the decoding power consumption. For achieving a desired Bit Error Rate (BER),
we introduce some fundamental results on the basis of iterative message-passing
algorithms for Low Density Parity Check Code (LDPC). To reduce energy
dissipation in decoder, LDPC based coded communications between sensors are
considered. Moreover, we evaluate the performance of LDPC at different code
rates and introduce Adaptive Iterative Decoding (AID) by exploiting threshold
on the number of iterations for a certain BER. In iterative LDPC decoding, the
total energy consumption of network is reduced by 20 to 25 percent.


title: Criticality and quenched disorder: rare regions vs. Harris criterion

abstract:
  We employ scaling arguments and optimal fluctuation theory to establish a
general relation between quantum Griffiths singularities and the Harris
criterion for quantum phase transitions in disordered systems. If a clean
critical point violates the Harris criterion, it is destabilized by weak
disorder. At the same time, the Griffiths dynamical exponent $z'$ diverges upon
approaching the transition, suggesting unconventional critical behavior. In
contrast, if the Harris criterion is fulfilled, power-law Griffiths
singularities can coexist with clean critical behavior but $z'$ saturates at a
finite value. We present applications of our theory to a variety of systems
including quantum spin chains, classical reaction-diffusion systems and
metallic magnets; and we discuss modifications for transitions above the upper
critical dimension. Based on these results we propose a unified classification
of phase transitions in disordered systems.


title:
Lower bounds for resonance counting functions for Schr\"odinger
  operators with fixed sign potentials in even dimensions

abstract:
  If the dimension $d$ is even, the resonances of the Schr\"odinger operator
$-\Delta +V$ on ${\mathbb R}^d$ with $V$ bounded and compactly supported are
points on $\Lambda$, the logarithmic cover of ${\mathbb C} \setminus \{0\}$. We
show that for fixed sign potentials $V$ and for nonzero integers $m$, the
resonance counting function for the $m$th sheet of $\Lambda$ has maximal order
of growth.


title: The Swift/BAT Hard X-ray Transient Monitor

abstract:
  The Swift/Burst Alert Telescope (BAT) hard X-ray transient monitor provides
near real-time coverage of the X-ray sky in the energy range 15-50 keV. The BAT
observes 88% of the sky each day with a detection sensitivity of 5.3 mCrab for
a full-day observation and a time resolution as fine as 64 seconds. The three
main purposes of the monitor are (1) the discovery of new transient X-ray
sources, (2) the detection of outbursts or other changes in the flux of known
X-ray sources, and (3) the generation of light curves of more than 900 sources
spanning over eight years. The primary interface for the BAT transient monitor
is a public web page. Between 2005 February 12 and 2013 April 30, 245 sources
have been detected in the monitor, 146 of them persistent and 99 detected only
in outburst. Among these sources, 17 were previously unknown and were
discovered in the transient monitor. In this paper, we discuss the methodology
and the data processing and filtering for the BAT transient monitor and review
its sensitivity and exposure. We provide a summary of the source detections and
classify them according to the variability of their light curves. Finally, we
review all new BAT monitor discoveries; for the new sources that are previously
unpublished, we present basic data analysis and interpretations.


title:
Improved $^{192,194,195,196}$Pt($n,\gamma $) and $^{192}$Ir($n,\gamma $)
  astrophysical reactions rates

abstract:
  $^{192}$Pt is produced solely by the slow neutron capture (\textit{s})
nucleosynthesis process and hence an accurate ($n$,$\gamma $) reaction rate for
this nuclide would allow its use as an important calibration point near the
termination of the \textit{s}-process nucleosynthesis flow. For this reason, we
have measured neutron capture and total cross sections for $%
^{192,194,195,196,nat}$Pt in the energy range from 10 eV to several hundred keV
at the Oak Ridge Electron Linear Accelerator. Measurements on the other Pt
isotopes were, in part, necessitated by the fact that only a relatively small
$^{192}$Pt sample of modest enrichment was available. Astrophysical $%
^{192,194,195,196}$Pt($n,\gamma $) reaction rates, accurate to approximately
3%--5 %, were calculated from these data. No accurate reaction rates have been
published previously for any of these isotopes. At \textit{s}-process
temperatures, previously recommended rates are larger (by as much as 35%) and
have significantly different shapes as functions of temperature, than our new
rates. We used our new Pt results, together with $^{191,193}$Ir(n,$% \gamma $)
data, to calibrate nuclear statistical model calculations and hence obtain an
improved rate for the unmeasured \textit{s}-process branching-point isotope
$^{192}$Ir.


title: Gravitational Coset Models

abstract:
  The algebra A(D-3)+++ dimensionally reduces to the E(D-1) symmetry algebra of
(12-D)-dimensional supergravity. An infinite set of five-dimensional
gravitational objects trivially embedded in D-dimensions is constructed by
identifying the null geodesic motion on cosets embedded in the generalised
Kac-Moody algebra A(D-3)+++. By analogy with supergravity these are bound
states of dual gravitons. The metric interpolates continuously between exotic
gravitational solutions generated by the action of the Geroch group but is not
a continuously transforming solution of the Einstein-Hilbert action. We
investigate mixed-symmetry fields in the brane sigma model, identify actions
for the full interpolating bound state and understand the obstruction to the
bound state being a solution of the Einstein-Hilbert action.


title:
Monte Carlo Simulation of 6MV Elekta Synergy Platform Linac photon beam
  using Gate/Geant4

abstract:
  The present work is devoted to develop a computational model using the Gate
Monte Carlo software for the simulation of a 6MV photon beam given by Elekta
Synergy Platform medical linear accelerator treatment head. The model includes
the major components of the multileaf accelerator head and a homogeneous water
phantom. Calculations were performed for a photon beam with several treatment
fields size ranging from 5*5 cm2 to 30*30 cm2 at 100 cm distance from source.
The simulation is successfully validated by comparison with experimental
distributions measured at the Regional Hassan II Oncology Center. Good
agreement between simulations and measurements was observed, with dose
differences of about 1.6% and 1.8% for depth doses and lateral dose profiles,
respectively. The gamma index comparisons were also performed where more than
98% of the points for all simulations passed the standard quality assurance
criteria of 3mm/3%.


title: An elementary fact about unlinked braid closures

abstract:
  Let n be a positive integer. We provide a Khovanov homology proof of the
following classical fact: If the closure of an n-strand braid is the
n-component unlink, then the braid is trivial.


title: Commensurable continued fractions

abstract:
  We compare two families of continued fractions algorithms, the symmetrized
Rosen algorithm and the Veech algorithm. Each of these algorithms expands real
numbers in terms of certain algebraic integers. We give explicit models of the
natural extension of the maps associated with these algorithms; prove that
these natural extensions are in fact conjugate to the first return map of the
geodesic flow on a related surface; and, deduce that, up to a conjugacy, almost
every real number has an infinite number of common approximants for both
algorithms.


title: Resiliently evolving supply-demand networks

abstract:
  The ability to design a transport network such that commodities are brought
from suppliers to consumers in a steady, optimal, and stable way is of great
importance for nowadays distribution systems. In this Letter, by using the
circuit laws of Kirchhoff and Ohm, we provide the exact capacities of the edges
that an optimal supply-demand network should have to operate stably under
perturbations. The perturbations we consider are the evolution of the
connecting topology, the decentralisation of hub sources or sinks, and the
intermittence of suppliers/consumers characteristics. We analyse these
conditions and the impact of our results, both on the current UK power-grid
structure and on numerically generated evolving archetypal network topologies.


title:
Herbig Stars' Near-Infrared Excess: An Origin in the Protostellar Disk's
  Magnetically-Supported Atmosphere

abstract:
  Young stars with masses 2-8 Suns, called the Herbig Ae and Be stars, often
show a near-infrared excess too large to explain with a
hydrostatically-supported circumstellar disk of gas and dust. At the same time
the accretion flow carrying the circumstellar gas to the star is thought to be
driven by magneto-rotational turbulence, which according to numerical MHD
modeling yields an extended low-density atmosphere supported by the magnetic
fields. We demonstrate that the base of the atmosphere can be optically-thick
to the starlight and that the parts lying near 1 AU are tall enough to double
the fraction of the stellar luminosity reprocessed into the near-infrared. We
generate synthetic spectral energy distributions (SEDs) using Monte Carlo
radiative transfer calculations with opacities for sub-micron silicate and
carbonaceous grains. The synthetic SEDs closely follow the median Herbig SED
constructed recently by Mulders and Dominik, and in particular match the large
near-infrared flux, provided the grains have a mass fraction close to
interstellar near the disk's inner rim.


title: Habitable worlds with no signs of life

abstract:
  'Most habitable worlds in the cosmos will have no remotely detectable signs
of life' is proposed as a biological hypothesis to be tested in studies of
exoplanets. Habitable planets could be discovered elsewhere in the Universe,
yet there are many hypothetical scenarios whereby the search for life on them
could yield negative results. Scenarios for habitable worlds with no remotely
detectable signatures of life include: planets that are habitable, but have no
biosphere (Uninhabited Habitable Worlds); planets with life, but lacking any
detectable surface signatures of that life (laboratory examples are provided)
and planets with life, where the concentration of atmospheric gases produced or
removed by biota are impossible to disentangle from abiotic processes because
of the lack of detailed knowledge of planetary conditions (the 'problem of
exoplanet thermodynamic uncertainty'). A rejection of the hypothesis would
require that the origin of life usually occurs on habitable planets, that
spectrally detectable pigments and/or metabolisms that produce unequivocal
biosignature gases (e.g. oxygenic photosynthesis) usually evolve and that the
organisms that harbour them usually achieve a sufficient biomass to produce
biosignatures detectable to alien astronomers.


title: Parameterization for qT-spectrum of inclusive Z-boson hadroproduction

abstract:
  We propose a simple parameterization for $q_T$-spectrum of inclusive
$Z$-boson production, and test it against world collider data at different
energies. The fit gives good agreement with the data, and indicates the
existence of two distinguishable breaks in the $q_T$-spectrum. Energy
dependences of the fitted parameters are discussed.


title:
A Model of Gene Expression Based on Random Dynamical Systems Reveals
  Modularity Properties of Gene Regulatory Networks

abstract:
  Here we propose a new approach to modeling gene expression based on the
theory of random dynamical systems (RDS) that provides a general coupling
prescription between the nodes of any given regulatory network given the
dynamics of each node is modeled by a RDS. The main virtues of this approach
are the following: (i) it provides a natural way to obtain arbitrarily large
networks by coupling together simple basic pieces, thus revealing the
modularity of regulatory networks; (ii) the assumptions about the stochastic
processes used in the modeling are fairly general, in the sense that the only
requirement is stationarity; (iii) there is a well developed mathematical
theory, which is a blend of smooth dynamical systems theory, ergodic theory and
stochastic analysis that allows one to extract relevant dynamical and
statistical information without solving the system; (iv) one may obtain the
classical rate equations form the corresponding stochastic version by averaging
the dynamic random variables (small noise limit). It is important to emphasize
that unlike the deterministic case, where coupling two equations is a trivial
matter, coupling two RDS is non-trivial, specially in our case, where the
coupling is performed between a state variable of one gene and the switching
stochastic process of another gene and, hence, it is not a priori true that the
resulting coupled system will satisfy the definition of a random dynamical
system. We shall provide the necessary arguments that ensure that our coupling
prescription does indeed furnish a coupled regulatory network of random
dynamical systems. Finally, the fact that classical rate equations are the
small noise limit of our stochastic model ensures that any validation or
prediction made on the basis of the classical theory is also a validation or
prediction of our model.


title:
Discrete and Continuous, Probabilistic Anticipation for Autonomous
  Robots in Urban Environments

abstract:
  This paper develops a probabilistic anticipation algorithm for dynamic
objects observed by an autonomous robot in an urban environment. Predictive
Gaussian mixture models are used due to their ability to probabilistically
capture continuous and discrete obstacle decisions and behaviors; the
predictive system uses the probabilistic output (state estimate and covariance)
of a tracking system, and map of the environment to compute the probability
distribution over future obstacle states for a specified anticipation horizon.
A Gaussian splitting method is proposed based on the sigma-point transform and
the nonlinear dynamics function, which enables increased accuracy as the number
of mixands grows. An approach to caching elements of this optimal splitting
method is proposed, in order to enable real-time implementation. Simulation
results and evaluations on data from the research community demonstrate that
the proposed algorithm can accurately anticipate the probability distributions
over future states of nonlinear systems.


title: Coupling light into graphene plasmons through surface acoustic waves

abstract:
  We propose a scheme for coupling laser light into graphene plasmons with the
help of electrically generated surface acoustic waves. The surface acoustic
wave forms a diffraction grating which allows to excite the long lived
phonon-like branch of the hybridized graphene plasmon-phonon dispersion with
infrared laser light. Our approach avoids patterning the graphene sheet, does
not rely on complicated optical near-field techniques, and allows to
electrically switch the coupling between far field radiation and propagating
graphene plasmons.


title: Random mass splitting and a quenched invariance principle

abstract:
  We will investigate a random mass splitting model and the closely related
random walk in a random environment (RWRE). The heat kernel for the RWRE at
time t is the mass splitting distribution at t. We prove a quenched invariance
principle for the RWRE which gives us a quenched central limit theorem for the
mass splitting model. Our RWRE has an environment which is changing with time.
We follow the outline for proving a quenched invariant process for a random
walk in a space-time random environment laid out by Rassoul-Agha and
Sepp\"al\"ainen which in turn was based on the work of Kipnis and Varadhan and
others.


title: From correlation functions to event shapes

abstract:
  We present a new approach to computing event shape distributions or, more
precisely, charge flow correlations in a generic conformal field theory (CFT).
These infrared finite observables are familiar from collider physics studies
and describe the angular distribution of global charges in outgoing radiation
created from the vacuum by some source. The charge flow correlations can be
expressed in terms of Wightman correlation functions in a certain limit. We
explain how to compute these quantities starting from their Euclidean analogues
by means of a non-trivial analytic continuation which, in the framework of CFT,
can elegantly be performed in Mellin space. The relation between the charge
flow correlations and Euclidean correlation functions can be reformulated
directly in configuration space, bypassing the Mellin representation, as a
certain Lorentzian double discontinuity of the correlation function integrated
along the cuts. We illustrate the general formalism in N=4 SYM, making use of
the well-known results on the four-point correlation function of half-BPS
scalar operators. We compute the double scalar flow correlation in N=4 SYM, at
weak and strong coupling and show that it agrees with known results obtained by
different techniques. One of the remarkable features of the N=4 theory is that
the scalar and energy flow correlations are proportional to each other.
Imposing natural physical conditions on the energy flow correlations
(finiteness, positivity and regularity), we formulate additional constraints on
the four-point correlation functions in N=4 SYM that should be valid at any
coupling and away from the planar limit.


title:
Non-universal Casimir Effect in Saturated Superfluid $^4$He Films at
  T$_\lambda$

abstract:
  Measurements of Casimir effects in $^4$He films in the vicinity of the bulk
superfluid transition temperature $T_\lambda$ have been carried out, where
changes in the film thickness and the superfluid density are both monitored as
a function of temperature. The Kosterlitz-Thouless superfluid onset temperature
in the film is found to occur just as the Casimir dip in the film thickness
from critical fluctuations becomes evident. Additionally, a new film-thickening
effect is observed precisely at $T_\lambda$ when the temperature is swept
extremely slowly. We propose that this is a non-universal Casimir effect
arising from the viscous suppression of second sound modes in the film.


title:
Gamma-ray burst models with general dynamics and fits to Fermi LAT
  bursts

abstract:
  We present a dissipative photospheric model for gamma-ray bursts where the
usual Band peak around MeV energies arises as synchrotron emission from around
the photosphere. We treat the initial acceleration in a general way and the GeV
emission arises as the interaction of photospheric radiation and the shocked
electrons at the deceleration radius. We show some applications of this model.


title: Strong asymptotic freeness for free orthogonal quantum groups

abstract:
  We prove that the normalized standard generators of the free orthogonal
quantum group $O_N^+$ converge strongly to a free semicircular system as $N \to
\infty$. Analogous results are obtained for the free unitary quantum groups,
and some applications are given.


title: Quantum Weak Measurements and Cosmology

abstract:
  The indeterminism of quantum mechanics generally permits the independent
specification of both an initial and a final condition on the state. Quantum
pre-and-post-selection of states opens up a new, experimentally testable,
sector of quantum mechanics, when combined with statistical averages of
identical weak measurements. In this paper I apply the theory of weak quantum
measurements combined with pre-and-post-selection to cosmology. Here,
pre-selection means specifying the wave function of the universe or, in a
popular semi-classical approximation, the initial quantum state of a subset of
quantum fields propagating in a classical back-ground spacetime. The novel
feature is post-selection: the additional specification of a condition on the
quantum state in the far future. I discuss "natural" final conditions, and show
how they may lead to potentially large and observable effects at the present
cosmological epoch. I also discuss how pre-and-post-selected quantum contrast
to the expectation value of the stress-energy-momentum tensor, resolving a
vigorous debate from the 1970's. The paper thus provides a framework for
computing large-scale cosmological effects arising from this new sector of
quantum mechanics. A simple experimental test is proposed.


title: Natural TeV-Scale Left-Right Seesaw for Neutrinos and Experimental Tests

abstract:
  We present a TeV-scale left-right ultraviolet completion of type-I seesaw for
neutrino masses based on the $SU(2)_L\times SU(2)_R\times U(1)_{B-L}$ gauge
group without parity, which leads to "large" light-heavy neutrino mixing while
keeping the neutrino masses small in a natural manner guaranteed by discrete
symmetries. We point out specific observable implications of this class of
models if the $SU(2)_R$-breaking scale is of order 5 TeV, in searches for
lepton flavor violating processes such as $\mu\to e\gamma$, $\mu\to 3 e$ and
$\mu-e$ conversion in nuclei, and lepton number violating processes such as
neutrinoless double beta decay as well as at the LHC. In particular, if the
upper limit on BR$(\mu\to e\gamma)$ improves by one order of magnitude, a large
range of the parameters of the model would be ruled out.


title:
Application of Expurgated PPM to Indoor Visible Light Communications -
  Part II: Access Networks

abstract:
  Providing network access for multiple users in a visible light communication
(VLC) system that utilizes white light emitting diodes (LED) as sources
requires new networking techniques adapted to the lighting features. In this
paper we introduce two multiple access techniques using expurgated PPM (EPPM)
that can be implemented using LEDs and support lighting features such as
dimming. Multilevel symbols are used to provide M-ary signaling for multiple
users using multilevel EPPM (MEPPM). Using these multiple-access schemes we are
able to control the optical peak to average power ratio (PAPR) in the system,
and hereby control the dimming level. In the first technique, the M-ary data of
each user is first encoded using an optical orthogonal code (OOC) assigned to
the user, and the result is fed into a EPPM encoder to generate a multilevel
signal. The second multiple access method uses sub-sets of the EPPM
constellation to apply MEPPM to the data of each user. While the first approach
has a larger Hamming distance between the symbols of each user, the latter can
provide higher bit-rates for users in VLC systems using bandwidth-limited LEDs.


title: Searching for pulsars using image pattern recognition

abstract:
  In this paper, we present a novel artificial intelligence (AI) program that
identifies pulsars from recent surveys using image pattern recognition with
deep neural nets---the PICS (Pulsar Image-based Classification System) AI. The
AI mimics human experts and distinguishes pulsars from noise and interferences
by looking for patterns from candidate. The information from each pulsar
candidate is synthesized in four diagnostic plots, which consist of up to
thousands pixel of image data. The AI takes these data from each candidate as
its input and uses thousands of such candidates to train its ~9000 neurons.
Different from other pulsar selection programs which use pre-designed patterns,
the PICS AI teaches itself the salient features of different pulsars from a set
of human-labeled candidates through machine learning. The deep neural networks
in this AI system grant it superior ability in recognizing various types of
pulsars as well as their harmonic signals. The trained AI's performance has
been validated with a large set of candidates different from the training set.
In this completely independent test, PICS ranked 264 out of 277 pulsar-related
candidates, including all 56 previously known pulsars, to the top 961 (1%) of
90008 test candidates, missing only 13 harmonics. The first non-pulsar
candidate appears at rank 187, following 45 pulsars and 141 harmonics. In other
words, 100% of the pulsars were ranked in the top 1% of all candidates, while
80% were ranked higher than any noise or interference. The performance of this
system can be improved over time as more training data are accumulated. This AI
system has been integrated into the PALFA survey pipeline and has discovered
six new pulsars to date.


title: Coupling and thermal equilibrium in general-covariant systems

abstract:
  A fully general-covariant formulation of statistical mechanics is still
lacking. We take a step toward this theory by studying the meaning of
statistical equilibrium for coupled, parametrized systems. We discuss how to
couple parametrized systems. We express the thermalization hypothesis in a
general-covariant context. This takes the form of vanishing of information
flux. An interesting relation emerges between thermal equilibrium and gauge.


title: On the Hall Effect in the pseudogap phase of cuprates

abstract:
  Angle resolved photoemission (ARPES) experiments reveal the coherent
electronic excitation in the energy spectrum of under- and optimally doped
cuprates at temperatures above their temperature of transition into
superconducting state only near nodal points on the parts of the "bare" Fermi
surface known as the Fermi arcs. That raises questions about the meaning and
possible interpretations of the experimental data. Below we derive expressions
for the Hall coefficient for the Fermi arc model both in weak and strong
magnetic fields.


title:
Formation of double glass in binary mixtures of anisotropic particles:
  Dynamic heterogeneities in rotations and displacements

abstract:
  We study glass behavior in a mixture of elliptic and circular particles in
two dimensions at low temperatures using an orientation-dependent Lennard-Jones
potential. The ellipses have a mild aspect ratio ($\sim 1.2$) and tend to align
at low temperatures, while the circular particles play the role of impurities
disturbing the ellipse orientations at a concentration of 20%. These impurities
have a size smaller than that of the ellipses and attract them in the
homeotropic alignment. As a result, the coordination number around each
impurity is mostly five or four in glassy states. We realize double glass,
where both the orientations and the positions are disordered but still hold
mesoscopic order. We find a strong heterogeneity in the flip motions of the
ellipses, which sensitively depends on the impurity clustering. The average
rotational diffusion constant is determined by rapidly flipping ellipses, which
still remain even at low temperatures in our model. In contrast, the non-flip
rotations (with angle changes not close to $\pm \pi$) are mainly caused by the
cooperative configuration changes involving many particles. Then, there arises
a long-time heterogeneity in the non-flip rotations closely correlated with the
dynamic heterogeneity in displacements.


title:
Low Transverse Momentum Heavy Quark Pair Production to Probe Gluon
  Tomography

abstract:
  We derive the transverse momentum dependent (TMD) factorization for heavy
quark pair production in deep inelastic scattering, where the total transverse
momentum is much smaller than the invariant mass of the pair. The factorization
is demonstrated at one-loop order, in both Ji-Ma-Yuan and Collins-11 schemes
for the TMD definitions, and the hard factors are calculated accordingly. Our
result provides a solid theoretical foundation for the phenomenological
investigations of the gluon TMDs in this process, and can be extended to other
similar hard processes, including dijet (di-hadron) production in DIS.


title:
An Exploratory Data Survey of Drug Name Incidence and Prevalence From
  the FDA's Adverse Event Reporting System, 2004 to 2012Q2

abstract:
  Drug Names, Population Level Surveillance and the FDA's Adverse Event
Reporting System: An Exploratory Data Survey of Drug Name Incidence and
Prevalence, 2004-2012Q2 Purpose: To count and monitor the drug names reported
in the publicly available version of the Federal Adverse Event Reporting System
(FAERS) from 2004 to 2012Q2 in a maximized sensitivity relational model.
Methods: Data mining and data modeling was conducted and event based summary
statistics with plots were created from over nine continuous years of
continuous FAERS data. Results: This FAERS model contains 344,452 individual
drug names and 432,541,994 count references which occurred across 4,148,761
human subjects in the 34 quarter study period. Plots for the top 100 scoring
drug name references are reported by year and quarter; the top 100 drug names
contain 143,384,240 references or 33% of all drug name references over 34
quarters of continuous FAERS data. Conclusions: While FAERS contains many drugs
and adverse event reports, its data pertains to very few of them. Drug name
incidence lends timely and effective surveillance of large populations of
Averse Event Reports and does not require the cause of the AE, nor its validity
to be known to detect a mass poisoning.


title:
A general class of free boundary problems for fully nonlinear parabolic
  equations

abstract:
  In this paper we consider the fully nonlinear parabolic free boundary problem
$$ \left\{\begin{array}{ll} F(D^2u) -\partial_t u=1 & \text{a.e. in}Q_1 \cap
\Omega\\ |D^2 u| + |\partial_t u| \leq K & \text{a.e. in}Q_1\setminus\Omega,
\end{array} \right. $$ where $K>0$ is a positive constant, and $\Omega$ is an
(unknown) open set.
  Our main result is the optimal regularity for solutions to this problem:
namely, we prove that $W_x^{2,n} \cap W_t^{1,n} $ solutions are locally
$C_x^{1,1}\cap C_t^{0,1} $ inside $Q_1$. A key starting point for this result
is a new BMO-type estimate which extends to the parabolic setting the main
result in \cite{CH}.
  Once optimal regularity for $u$ is obtained, we also show regularity for the
free boundary $\partial\Omega\cap Q_1$ under the extra condition that $\Omega
\supset \{u \neq 0 \}$, and a uniform thickness assumption on the coincidence
set $\{u = 0 \}$,


title:
A discontinuous functional for linear response time-dependent density
  functional theory: the exact-exchange kernel and approximate forms

abstract:
  We present a detailed study of the exact-exchange (EXX) kernel of
time-dependent density functional theory with an emphasis on its discontinuity
at integer particle numbers. It was recently found that this exact property
leads to sharp peaks and step features in the kernel that diverge in the
dissociation limit of diatomic systems [Hellgren and Gross, Phys. Rev. A,
022514 (2012)]. To further analyze the discontinuity of the kernel we here make
use of two different approximations to the EXX kernel: the PGG approximation
and a common energy denominator approximation (CEDA). It is demonstrated that
whereas the PGG approximation neglects the discontinuity the CEDA includes it
explicitly. By studying model molecular systems it is shown that the so-called
field counter-acting effect in the density functional description of molecular
chains can be viewed in terms of the discontinuity of the static kernel. The
role of the frequency dependence is also investigated, highlighting its
importance for long-range charge transfer excitations as well as inner-shell
excitations.


title: Dynamics of entanglement in a dissipative Bose-Hubbard dimer

abstract:
  We study the connection between the semiclassical phase space of the
Bose--Hubbard dimer and inherently quantum phenomena in this model, such as
entanglement and dissipation-induced coherence. Near the semiclassical
self-trapping fixed points, the dynamics of EPR entanglement and condensate
fraction consists of beats among just three eigenstates. Since persistent EPR
entangled states arise only in the neighborhood of these fixed points, our
analysis explains essentially all of the entanglement dynamics in the system.
We derive accurate analytical approximations by expanding about the
strong-coupling limit; surprisingly, their realm of validity is nearly the
entire parameter space for which the self-trapping fixed points exist. Finally,
we show significant enhancement of entanglement can be produced by applying
localized dissipation.


title: On partition function and Weyl anomaly of conformal higher spin fields

abstract:
  We study 4-dimensional higher-derivative conformal higher spin (CHS) fields
generalising Weyl graviton and conformal gravitino. They appear, in particular,
as "induced" theories in the AdS/CFT context. We consider their partition
function on curved Einstein-space backgrounds like (A)dS or sphere and
Ricci-flat spaces. Remarkably, the bosonic (integer spin s) CHS partition
function appears to be given by a product of partition functions of the
standard 2nd-derivative "partially massless" spin s fields, generalising the
previously known expression for the 1-loop Weyl graviton (s=2) partition
function. We compute the corresponding spin s Weyl anomaly coefficients a_s and
c_s. Our result for a_s reproduces the expression found recently in
arXiv:1306.5242 by an indirect method implied by AdS/CFT (which relates the
partition function of a CHS field on S^4 to a ratio of known partition
functions of massless higher spin field in AdS_5 with alternate boundary
conditions). We also obtain similar results for the fermionic CHS fields. In
this half-integer spin s case the CHS partition function on (A)dS background is
given by a product of squares of "partially massless" spin s partition
functions and one extra factor corresponding to a special massive conformally
invariant spin s field. It was noticed in arXiv:1306.5242 that the sum of the
bosonic a_s coefficients over all spins s is zero when computed using the
zeta-function regularization, and we observe that the same property is true
also in the fermionic case, suggesting that the corresponding conformal higher
spin theory may be consistent at the quantum level.


title:
Optimal control of strong-field ionization with time-dependent
  density-functional theory

abstract:
  We show that quantum optimal control theory (OCT) and time-dependent
density-functional theory (TDDFT) can be combined to provide realistic
femtosecond laser pulses for an enhanced ionization yield in many-electron
systems. Using the H$_2$-molecule as a test case, the optimized laser pulse
from the numerically exact scheme is compared to pulses obtained from OCT+TDDFT
within the TD exact-exchange (TDEXX) and the TD local-density approximation
(TDLDA). We find that the TDDFT-pulses produces an ionization yield of up to
50% when applied to the exact system. In comparison, pulses with a single
frequency but the same fluence typically reach to yields around 5-15%, unless
the frequency is carefully tuned into a Fano-type resonance that leads to $\sim
30%$ yield. On the other hand, optimization within the exact system alone leads
to yields higher than 80%, demonstrating that correlation effects beyond the
TDEXX and TDLDA can give rise to even more efficient ionization mechanisms.


title: Online Tensor Methods for Learning Latent Variable Models

abstract:
  We introduce an online tensor decomposition based approach for two latent
variable modeling problems namely, (1) community detection, in which we learn
the latent communities that the social actors in social networks belong to, and
(2) topic modeling, in which we infer hidden topics of text articles. We
consider decomposition of moment tensors using stochastic gradient descent. We
conduct optimization of multilinear operations in SGD and avoid directly
forming the tensors, to save computational and storage costs. We present
optimized algorithm in two platforms. Our GPU-based implementation exploits the
parallelism of SIMD architectures to allow for maximum speed-up by a careful
optimization of storage and data transfer, whereas our CPU-based implementation
uses efficient sparse matrix computations and is suitable for large sparse
datasets. For the community detection problem, we demonstrate accuracy and
computational efficiency on Facebook, Yelp and DBLP datasets, and for the topic
modeling problem, we also demonstrate good performance on the New York Times
dataset. We compare our results to the state-of-the-art algorithms such as the
variational method, and report a gain of accuracy and a gain of several orders
of magnitude in the execution time.


title: Vector-like $B$ pair production at future $pp$ colliders

abstract:
  The capabilities of 14 TeV and 33 TeV pp colliders for discovering
vector-like B quarks is examined. These studies were carried out as part of the
Snowmass Community Planning exercise.


title: Instabilities near the QCD phase transition in the holographic models

abstract:
  The paper discusses phenomena close to the critical QCD temperature, using
the holographic model. One issue studied is the overcooled high-T phase, in
which we calculate quasi normal sound modes. We do not find instabilities
associated with other first order phase transitions, but nevertheless observe
drastic changes in sound propagation/dissipation. The rest of the paper
considers a cluster of the high-T phase in the UV in coexistence with the low-T
phase, in a simplified ansatz in which the wall separating them is positioned
only in the holographic coordinate. This allows to find the force on the wall
and classical motion of the cluster. When classical motion is forbidden, we
evaluate tunneling probability through the remaining barrier.


title:
SKYNET: an efficient and robust neural network training tool for machine
  learning in astronomy

abstract:
  We present the first public release of our generic neural network training
algorithm, called SkyNet. This efficient and robust machine learning tool is
able to train large and deep feed-forward neural networks, including
autoencoders, for use in a wide range of supervised and unsupervised learning
applications, such as regression, classification, density estimation,
clustering and dimensionality reduction. SkyNet uses a `pre-training' method to
obtain a set of network parameters that has empirically been shown to be close
to a good solution, followed by further optimisation using a regularised
variant of Newton's method, where the level of regularisation is determined and
adjusted automatically; the latter uses second-order derivative information to
improve convergence, but without the need to evaluate or store the full Hessian
matrix, by using a fast approximate method to calculate Hessian-vector
products. This combination of methods allows for the training of complicated
networks that are difficult to optimise using standard backpropagation
techniques. SkyNet employs convergence criteria that naturally prevent
overfitting, and also includes a fast algorithm for estimating the accuracy of
network outputs. The utility and flexibility of SkyNet are demonstrated by
application to a number of toy problems, and to astronomical problems focusing
on the recovery of structure from blurred and noisy images, the identification
of gamma-ray bursters, and the compression and denoising of galaxy images. The
SkyNet software, which is implemented in standard ANSI C and fully parallelised
using MPI, is available at http://www.mrao.cam.ac.uk/software/skynet/.

categories: astro-ph.IM cs.LG cs.NE physics.data-an stat.ML


title: Four-qubit pure states as fermionic states

abstract:
  The embedding of the $n$-qubit space into the $n$-fermion space with $2n$
modes is a widely used method in studying various aspects of these systems.
This simple mapping raises a crucial question: does the embedding preserve the
entanglement structure? It is known that the answer is affirmative for $n=2$
and $n=3$. That is, under either local unitary (LU) operations or with respect
to stochastic local operations and classical communication (SLOCC), there is a
one-to-one correspondence between the 2- (or 3)-qubit orbits and the 2- (or
3)-fermion orbits with 4 (or 6) modes. However these results do not generalize
as the mapping from the $n$-qubit orbits to the $n$-fermion orbits with $2n$
modes is no longer surjective for $n>3$. Here we consider the case of $n=4$. We
show that surprisingly, the orbit mapping from qubits to fermions remains
injective under SLOCC, and a similar result holds under LU for generic orbits.
As a byproduct, we obtain a complete answer to the problem of SLOCC equivalence
of pure 4-qubit states.


title: Measurements according to Consistent Histories

abstract:
  We critically evaluate the treatment of the notion of measurement in the
Consistent Histories approach to quantum mechanics. We find such a treatment
unsatisfactory because it relies, often implicitly, on elements external to
those provided by the formalism. In particular, we note that, in order for the
formalism to be informative when dealing with measurement scenarios, one needs
to assume that the appropriate choice of framework is such that apparatuses are
always in states of well defined pointer positions after measurements. The
problem is that there is nothing in the formalism to justify this assumption.
We conclude that the Consistent Histories approach, contrary to what is claimed
by its proponents, fails to provide a truly satisfactory resolution for the
measurement problem in quantum theory.


title:
Growth and micromagnetism of self-assembled epitaxial fcc(111) cobalt
  dots

abstract:
  We developed the self-assembly of epitaxial submicrometer-sized
face-centered-cubic (fcc) Co(111) dots using pulsed laser deposition. The dots
display atomically-fl at facets, from which the ratios of surface and interface
energies for fcc Co are deduced. Zero- field magnetic structures are
investigated with magnetic force and lorentz microscopies, revealing
vortex-based flux-closure patterns. A good agreement is found with
micromagnetic simulations.


title:
Comments on holographic current algebras and asymptotically flat four
  dimensional spacetimes at null infinity

abstract:
  We follow the spirit of a recent proposal to show that previous computations
for asymptotically flat spacetimes in four dimensions at null infinity can be
re-interpreted in terms of a well-defined holographic current algebra for the
time component of the currents. The analysis is completed by the current
algebra for the spatial components.


title:
Probabilistic global well-posedness for the supercritical nonlinear
  harmonic oscillator

abstract:
  Thanks to an approach inspired from Burq-Lebeau \cite{bule}, we prove
stochastic versions of Strichartz estimates for Schr\"odinger with harmonic
potential. As a consequence, we show that the nonlinear Schr\"odinger equation
with quadratic potential and any polynomial non-linearity is almost surely
locally well-posed in $L^{2}(\R^{d})$ for any $d\geq 2$. Then, we show that we
can combine this result with the high-low frequency decomposition method of
Bourgain to prove a.s. global well-posedness results for the cubic equation:
when $d=2$, we prove global well-posedness in $\H^{s}(\R^{2})$ for any $s>0$,
and when $d=3$ we prove global well-posedness in $\H^{s}(\R^{3})$ for any
$s>1/6$, which is a supercritical regime. Furthermore, we also obtain almost
sure global well-posedness results with scattering for NLS on $\R^{d}$ without
potential. We prove scattering results for $L^2-$supercritical equations and
$L^2-$subcritical equations with initial conditions in $L^2$ without additional
decay or regularity assumption.


title: Foundations of Garside Theory

abstract:
  This text consists of the introduction, table of contents, and bibliography
of a long manuscript (703 pages) that is currently submitted for publication.
This manuscript develops an extension of Garside's approach to braid groups and
provides a unified treatment for the various algebraic structures that appear
in this context. The complete text can be found at
http://www.math.unicaen.fr/~garside/Garside.pdf.


title: Triple Variational Principles for Self-Adjoint Operator Functions

abstract:
  For a very general class of unbounded self-adjoint operator function we prove
upper bounds for eigenvalues which lie within arbitrary gaps of the essential
spectrum. These upper bounds are given by triple variations. Furthermore, we
find conditions which imply that a point is in the resolvent set. For norm
resolvent continuous operator functions we show that the variational inequality
becomes an equality.


title: Vibrations of Jammed Disk Packings with Hertzian Interactions

abstract:
  Contact breaking and Hertzian interactions between grains can both give rise
to nonlinear vibrational response of static granular packings. We perform
molecular dynamics simulations at constant energy in 2D of frictionless
bidisperse disks that interact via Hertzian spring potentials as a function of
energy and measure directly the vibrational response from the Fourier transform
of the velocity autocorrelation function. We compare the measured vibrational
response of static packings near jamming onset to that obtained from the
eigenvalues of the dynamical matrix to determine the temperature above which
the linear response breaks down. We compare packings that interact via
single-sided (purely repulsive) and double-sided Hertzian spring interactions
to disentangle the effects of the shape of the potential from contact breaking.
Our studies show that while Hertzian interactions lead to weak nonlinearities
in the vibrational behavior (e.g. the generation of harmonics of the
eigenfrequencies of the dynamical matrix), the vibrational response of static
packings with Hertzian contact interactions is dominated by contact breaking as
found for systems with repulsive linear spring interactions.


title: Linear Degrees of Freedom of the X-Channel with Delayed CSIT

abstract:
  We establish the degrees of freedom of the two-user X-channel with delayed
channel knowledge at transmitters (i.e., delayed CSIT), assuming linear coding
strategies at the transmitters. We derive a new upper bound and characterize
the linear degrees of freedom of this network to be 6/5. The converse builds
upon our development of a general lemma that shows that, if two distributed
transmitters employ linear strategies, the ratio of the dimensions of received
linear subspaces at the two receivers cannot exceed 3/2, due to delayed CSIT.
As a byproduct, we also apply this general lemma to the three-user interference
channel with delayed CSIT, thereby deriving a new upper bound of 9/7 on its
linear degrees of freedom. This is the first bound that captures the impact of
delayed CSIT on the degrees of freedom of this network, under the assumption of
linear encoding strategies.


title:
Quantum circuits based on qutrits as a tool for solving systems of
  linear equations

abstract:
  Recently, it has been presented some algorithms and physical models which
give prospects for construction of quantum computers capable to solve systems
of linear equations. The common feature which is shared in these works is the
use of qubits which allow to solve systems with $2^n$ variables. In this work
we propose a quantum circuit based on qutrits architecture which directly
allows for solving systems of equations with three variables. Proposed circuit
can be easily generalized to those with $3^n$ variables. We also present some
numerical experiments to verify the correctness of proposed solution.


title: Piggy-backing protein domains with Formal Concept Analysis

abstract:
  Identifying reliable domain-domain interactions (DDIs) will increase our
ability to predict novel protein-protein interactions (PPIs), to unravel
interactions in protein complexes, and thus gain more information about the
function and behavior of genes. One of the challenges of identifying reliable
DDIs is domain promiscuity. Promiscuous domains are domains that can occur in
many domain architectures and are therefore found in many proteins. This
becomes a problem for a method where the score of a domain-pair is the ratio
between observed and expected frequencies because the PPI network is sparse. As
such, many protein-pairs will be non-interacting and domain-pairs with
promiscuous domains will be penalized. This domain promiscuity challenge to the
problem of inferring reliable DDIs from PPIs has been recognized, and a number
of work-arounds have been proposed. In this paper, we report an application of
Formal Concept Analysis (FCA) to this problem. We find that the relationship
between formal concepts provide a natural way for rare domains to elevate the
rank of promiscuous domains, and enrich highly ranked domain-pairs with
reliable DDIs. This piggy-backing of promiscuous domains onto rare domains is
possible due to the domain architecture of proteins which mixes promiscuous
with rare domains.


title: Multi-Time Wave Functions for Quantum Field Theory

abstract:
  Multi-time wave functions such as $\phi(t_1,x_1,\ldots,t_N,x_N)$ have one
time variable $t_j$ for each particle. This type of wave function arises as a
relativistic generalization of the wave function $\psi(t,x_1,\ldots,x_N)$ of
non-relativistic quantum mechanics. We show here how a quantum field theory can
be formulated in terms of multi-time wave functions. We mainly consider a
particular quantum field theory that features particle creation and
annihilation. Starting from the particle-position representation of state
vectors in Fock space, we introduce multi-time wave functions with a variable
number of time variables, set up multi-time evolution equations, and show that
they are consistent. Moreover, we discuss the relation of the multi-time wave
function to two other representations, the Tomonaga-Schwinger representation
and the Heisenberg picture in terms of operator-valued fields on space-time. In
a certain sense and under natural assumptions, we find that all three
representations are equivalent; yet, we point out that the multi-time
formulation has several technical and conceptual advantages.


title: The R-operator for Modular Double

abstract:
  We construct the R-operator -- solution of the Yang-Baxter equation acting in
the tensor product of two infinite-dimensional representations of Faddeev's
modular double. This R-operator intertwines the product of two L-operators
associated with the modular double and it is built from three basic operators
generating the permutation group of four parameters S_4.


title: On-shell Techniques and Universal Results in Quantum Gravity

abstract:
  We compute the leading post-Newtonian and quantum corrections to the Coulomb
and Newtonian potentials using the full modern arsenal of on-shell techniques;
we employ spinor-helicity variables everywhere, use the Kawai-Lewellen-Tye
(KLT) relations to derive gravity amplitudes from gauge theory and use
unitarity methods to extract the terms needed at one-loop order. We stress that
our results are universal and thus will hold in any quantum theory of gravity
with the same low-energy degrees of freedom as we are considering. Previous
results for the corrections to the same potentials, derived historically using
Feynman graphs, are verified explicitly, but our approach presents a huge
simplification, since starting points for the computations are compact and
tedious index contractions and various complicated integral reductions are
eliminated from the onset, streamlining the derivations. We also analyze the
spin dependence of the results using the KLT factorization, and show how the
spinless correction in the framework are easily seen to be independent of the
interacting matter considered.


title:
An Urn Model Approach for Deriving Multivariate Generalized
  Hypergeometric Distributions

abstract:
  We propose new generalized multivariate hypergeometric distributions, which
extremely resemble the classical multivariate hypergeometric distributions. The
proposed distributions are derived based on an urn model approach. In contrast
to existing methods, this approach does not involve hypergeometric series.


title: Survey of Insurance Fraud Detection Using Data Mining Techniques

abstract:
  With an increase in financial accounting fraud in the current economic
scenario experienced, financial accounting fraud detection has become an
emerging topics of great importance for academics, research and industries.
Financial fraud is a deliberate act that is contrary to law, rule or policy
with intent to obtain unauthorized financial benefit and intentional
misstatements or omission of amounts by deceiving users of financial
statements, especially investors and creditors. Data mining techniques are
providing great aid in financial accounting fraud detection, since dealing with
the large data volumes and complexities of financial data are big challenges
for forensic accounting. Financial fraud can be classified into four: bank
fraud, insurance fraud, securities and commodities fraud. Fraud is nothing but
wrongful or criminal trick planned to result in financial or personal gains.
This paper describes the more details on insurance sector related frauds and
related solutions. In finance, insurance sector is doing important role and
also it is unavoidable sector of every human being.


title:
Thermodynamics of Phantom Energy Accreting onto a Black Hole in
  Einstein-Power-Maxwell Gravity

abstract:
  In this paper, we investigate the phantom energy accretion onto 3D black hole
formulated in Einstein-Power-Maxwell theory. We have presented the conditions
for critical accretion of phantom energy onto black hole. Further, we discuss
the thermodynamics of phantom energy accreting onto black hole and found that
first law of thermodynamics is easily satisfied while second law and
generalized second law of thermodynamics remain invalid and conditionally
valid, respectively. The results for BTZ black hole can be recovered by taking
Maxwellian contribution equal to zero.


title: Non-hermitean hamiltonians with unitary and antiunitary symmetry

abstract:
  We analyze several non-Hermitian Hamiltonians with antiunitary symmetry from
the point of view of their point-group symmetry. It enables us to predict the
degeneracy of the energy levels and to reduce the dimension of the matrices
necessary for the diagonalization of the Hamiltonian in a given basis set. We
can also classify the solutions according to the irreducible representations of
the point group and thus analyze their properties separately. One of the main
results of this paper is that some PT-symmetric Hamiltonians with point-group
symmetry $C_{2v}$ exhibit complex eigenvalues for all values of a potential
parameter. In such cases the PT phase transition takes place at the trivial
Hermitian limit which suggests that the phenomenon is not robust. Point-group
symmetry enables us to explain such anomalous behaviour and to choose a
suitable antiunitary operator for the PT symmetry.


title:
A direct dynamical measurement of the Milky Way's disk surface density
  profile, disk scale length, and dark matter profile at 4 kpc < R < 9 kpc

abstract:
  We present and apply rigorous dynamical modeling with which we infer
unprecedented constraints on the stellar and dark matter mass distribution
within our Milky Way (MW), based on large sets of phase-space data on
individual stars. Specifically, we model the dynamics of 16,269 G-type dwarfs
from SEGUE, which sample 5 < R_GC/kpc < 12 and 0.3 < |Z|/kpc < 3. We
independently fit a parameterized MW potential and a three-integral,
action-based distribution function (DF) to the phase-space data of 43 separate
abundance-selected sub-populations (MAPs), accounting for the complex selection
effects affecting the data. We robustly measure the total surface density
within 1.1 kpc of the mid-plane to 5% over 4.5 < R_GC/kpc < 9. Using metal-poor
MAPs with small radial scale lengths as dynamical tracers probes 4.5 < R_GC/kpc
< 7, while MAPs with longer radial scale lengths sample 7 < R_GC/kpc < 9. We
measure the mass-weighted Galactic disk scale length to be R_d = 2.15+/-0.14
kpc, in agreement with the photometrically inferred spatial distribution of
stellar mass. We thereby measure dynamically the mass of the Galactic stellar
disk to unprecedented accuracy: M_* = 4.6+/-0.3+3.0x(R_0/kpc-8)x10^{10}Msun and
a total local surface density of \Sigma_{R_0}(Z=1.1 kpc) = 68+/-4 Msun/pc^2 of
which 38+/-4 Msun/pc^2 is contributed by stars and stellar remnants. By
combining our surface density measurements with the terminal velocity curve, we
find that the MW's disk is maximal in that V_{c,disk} / V_{c,total} =
0.83+/-0.04 at R=2.2 R_d. We also constrain for the first time the radial
profile of the dark halo at such small Galactocentric radii, finding that
\rho_{DM} (r;near R_0) \propto 1 / r^\alpha with \alpha < 1.53 at 95%
confidence. Our results show that action-based distribution-function modeling
of complex stellar data sets is now a feasible approach that will be fruitful
for interpreting Gaia data.


title: Probing the Colour Structure of the Top Quark Forward-Backward Asymmetry

abstract:
  We point out that QCD coherence effects can help to identify the colour
structure of possible new physics contributions to the anomalously large
forward-backward asymmetry in top quark pair production. New physics models
that yield the same inclusive asymmetry make different predictions for its
dependence on the transverse momentum of the pair, if they have different
colour structures. From both a fixed-order effective field theory approach and
Monte Carlo studies of specific models, we find that an s-channel octet
structure is preferred.


title: Magnetic shielding of exomoons beyond the circumplanetary habitable edge

abstract:
  With most planets and planetary candidates detected in the stellar habitable
zone (HZ) being super-Earths and gas giants, rather than Earth-like planets, we
naturally wonder if their moons could be habitable. The first detection of such
an exomoon has now become feasible, and due to observational biases it will be
at least twice as massive as Mars. But formation models predict moons can
hardly be as massive as Earth. Hence, a giant planet's magnetosphere could be
the only possibility for such a moon to be shielded from cosmic and stellar
high-energy radiation. Yet, the planetary radiation belt could also have
detrimental effects on exomoon habitability. We here synthesize models for the
evolution of the magnetic environment of giant planets with thresholds from the
runaway greenhouse (RG) effect to assess the habitability of exomoons. For
modest eccentricities, we find that satellites around Neptune-sized planets in
the center of the HZ around K dwarf stars will either be in an RG state and not
be habitable, or they will be in wide orbits where they will not be affected by
the planetary magnetosphere. Saturn-like planets have stronger fields, and
Jupiter-like planets could coat close-in habitable moons soon after formation.
Moons at distances between about 5 and 20 planetary radii from a giant planet
can be habitable from an illumination and tidal heating point of view, but
still the planetary magnetosphere would critically influence their
habitability.


title: Hilbert Series for Moduli Spaces of Instantons on C^2/Z_n

abstract:
  We study chiral gauge-invariant operators on moduli spaces of G instantons
for any classical group G on A-type ALE spaces using Hilbert Series (HS).
Moduli spaces of instantons on an ALE space can be realized as Higgs branches
of certain quiver gauge theories which appear as world-volume theories on Dp
branes in a Dp-D(p+4) system with the D(p+4) branes (with or without O(p+4)
planes) wrapping the ALE space. We study in detail a list of quiver gauge
theories which are related to G-instantons of arbitrary ranks and instanton
numbers on a generic A_{n-1} ALE space and discuss the corresponding brane
configurations. For a large class of theories, we explicitly compute the Higgs
branch HS which reveals various algebraic/geometric aspects of the moduli space
such as the dimension of the space, generators of the moduli space and
relations connecting them. In a large number of examples involving lower rank
instantons, we demonstrate that HS for equivalent instantons of isomorphic
gauge groups but very different quiver descriptions do indeed agree, as
expected.


title:
A Deep Keck/NIRC2 Search for Thermal Emission from Planetary Companions
  Orbiting Fomalhaut

abstract:
  We present deep Keck/NIRC2 1.6 and 3.8 $\mu m$ imaging of Fomalhaut to
constrain the near-infrared (IR) brightness of Fomalhaut b, recently confirmed
as a likely planet (Currie et al. 2012a), and search for additional planets at
r_proj = 15--150 AU. Using advanced/novel PSF subtraction techniques, we
identify seven candidate substellar companions at projected separations
comparable to Fomalhaut b. However, multi-epoch data shows them to be
background objects. We set a new 3-$\sigma$ upper limit for Fomalhaut b's
H-band brightness of m(H) $\sim$ 23.15 or 1.5 to 4.5 M_J, depending on the
system age and planet cooling models used. We do not recover the possible point
source reported from Spitzer/IRAC data: at its location detection limits are
similar to those for Fomalhaut b. Our data when combined with other recent work
rule out planets with masses and projected separations comparable to HR 8799
bcde and planets with masses M $>$ 3 M_{J} at r_proj $>$ 45 AU. The James Webb
Space Telescope will likely be required to shed substantial further light on
Fomalhaut's planetary system.


title:
The Obscured Fraction of AGN in the XMM-COSMOS Survey: A Spectral Energy
  Distribution Perspective

abstract:
  The fraction of AGN luminosity obscured by dust and re-emitted in the mid-IR
is critical for understanding AGN evolution, unification, and parsec-scale AGN
physics. For unobscured (Type-1) AGN, where we have a direct view of the
accretion disk, the dust covering factor can be measured by computing the ratio
of re-processed mid-IR emission to intrinsic nuclear bolometric luminosity. We
use this technique to estimate the obscured AGN fraction as a function of
luminosity and redshift for 513 Type-1 AGN from the XMM-COSMOS survey. The
re-processed and intrinsic luminosities are computed by fitting the 18-band
COSMOS photometry with a custom SED-fitting code, which jointly models emission
from: hot-dust in the AGN torus, the accretion disk, and the host-galaxy. We
find a relatively shallow decrease of the luminosity ratio as a function of
Lbol, which we interpret as a corresponding decrease in the obscured fraction.
In the context of the receding torus model, where dust sublimation reduces the
covering factor of more luminous AGN, our measurements require a torus height
which increases with luminosity as h ~ Lbol^{0.3-0.4}. Our obscured
fraction-luminosity relation agrees with determinations from SDSS censuses of
Type-1 and Type-2 quasars, and favors a torus optically thin to mid-IR
radiation. We find a much weaker dependence of obscured fraction on 2-10 keV
luminosity than previous determinations from X-ray surveys, and argue that
X-ray surveys miss a significant population of highly obscured Compton-thick
AGN. Our analysis shows no clear evidence for evolution of obscured fraction
with redshift.


title: Ultra-Compact High Velocity Clouds as Minihalos and Dwarf Galaxies

abstract:
  We present dark-matter minihalo models for the Ultra-Compact High Velocity HI
Clouds (UCHVCs) recently discovered in the 21 cm ALFALFA survey. We assume
gravitational confinement of 10^4 K HI gas by flat-cored dark-matter subhalos
within the Local Group. We show that for flat cores, typical (median)
tidally-stripped cosmological subhalos at redshift z=0 have dark-matter masses
of ~10^7 M_{sun} within the central 300 pc (independent of total halo mass),
consistent with the "Strigari mass scale" observed in low-luminosity dwarf
galaxies. Flat-cored subhalos also resolve the mass-discrepancy between
simulated and observed satellites around the Milky Way. For the UCHVCs we
calculate the photoionization-limited hydrostatic gas profiles for any
distance-dependent total observed HI mass and predict the associated
(projected) HI half-mass radii, assuming the clouds are embedded in distant (d
> 300 kpc) and unstripped subhalos. For a typical UCHVC (0.9 Jy km/s) we
predict physical HI half-mass radii of 0.18 to 0.35 kpc (or angular sizes of
0.6 to 2.1 arcmin) for distances ranging from 300 kpc to 2 Mpc. As a
consistency check we model the gas rich dwarf galaxy Leo T, for which there is
a well-resolved HI column density profile and a known distance (420 kpc). For
Leo T we find that a subhalo with M_{300} ~ 8 (+/-0.2) 10^6 M_{sun} best fits
the observed HI profile. We derive an upper limit of P_{HIM} < 150 K/cm^3 for
the pressure of any enveloping hot IGM gas at the distance of Leo T. Our
analysis suggests that some of the UCHVCs may in fact constitute a population
of 21-cm-selected but optically-faint dwarf galaxies in the Local Group.


title: Locality of temperature

abstract:
  This work is concerned with thermal quantum states of Hamiltonians on spin
and fermionic lattice systems with short range interactions. We provide results
leading to a local definition of temperature, thereby extending the notion of
"intensivity of temperature" to interacting quantum models. More precisely, we
derive a perturbation formula for thermal states. The influence of the
perturbation is exactly given in terms of a generalized covariance. For this
covariance, we prove exponential clustering of correlations above a universal
critical temperature that upper bounds physical critical temperatures such as
the Curie temperature. As a corollary, we obtain that above the critical
temperature, thermal states are stable against distant Hamiltonian
perturbations. Moreover, our results imply that above the critical temperature,
local expectation values can be approximated efficiently in the error and the
system size.

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


title:
Towards A Removal of Temperature Dependencies from Abundance
  Determinations

abstract:
  The metal content of a galaxy is a key property for distinguishing between
viable galaxy evolutionary scenarios, and it strongly influences many of the
physical processes in the interstellar medium. An absolute and robust
determination of extragalactic metallicities is essential in constraining
models of chemical enrichment and chemical evolution, however, current gas
phase abundance determinations from optical fine-structure lines are uncertain
to 0.8 dex as conversion of these optical line fluxes to abundances is strongly
dependent on the electron temperature of the ionized gas. In contrast, the
far-IR emission lines can be used to derive an O++ abundance that is relatively
insensitive to temperature, while the ratio of the optical to far-IR lines
provides a consistent temperature to be used in the derivation of an O$^+$
abundance. We present observations of the [O III] 88 \micron\ fine-structure
line in NGC 628 that were obtained as part of the KINGFISH program. These data
are combined with optical IFU data to derive oxygen abundances for seven HII
regions. We find the abundance of these regions to all lie between the high and
low values of strong line calibrations and in agreement with estimates that
assume temperature fluctuations are present in the HII regions.


title: Black holes with massive graviton hair

abstract:
  No-hair theorems exclude the existence of nontrivial scalar and massive
vector hair outside four-dimensional, static, asymptotically flat black-hole
spacetimes. We show, by explicitly building nonlinear solutions, that black
holes can support massive graviton hair in theories of massive gravity. These
hairy solutions are, most likely, the generic end state of the recently
discovered monopole instability of Schwarzschild black holes in massive
graviton theories.


title:
Naive Dimensional Analysis Counting of Gauge Theory Amplitudes and
  Anomalous Dimensions

abstract:
  We show that naive dimensional analysis (NDA) is equivalent to the result
that L-loop scattering amplitudes have perturbative order N=L+Delta, with a
shift Delta that depends on the NDA-weight of operator insertions. The NDA
weight of an operator is defined in this paper, and the general NDA formula for
perturbative order N is derived. The formula is used to explain why the
one-loop anomalous dimension matrix for dimension-six operators in the Standard
Model effective field theory has entries with perturbative order ranging from 0
to 4. The results in this paper are valid for an arbitrary effective field
theory, and they constrain the coupling constant dependence of anomalous
dimensions and scattering amplitudes in a general effective field theory.


title: Nuclear binding energies from a BPS Skyrme model

abstract:
  Recently, within the space of generalized Skyrme models, a BPS submodel was
identified which reproduces some bulk properties of nuclear matter already on a
classical level and, as such, constitutes a promising field theory candidate
for the detailed and reliable description of nuclei and hadrons. Here we extend
and further develop these investigations by applying the model to the
calculation of nuclear binding energies. Concretely, we calculate these binding
energies by including the classical soliton energies, the excitation energies
from the collective coordinate quantization of spin and isospin, the
electrostatic Coulomb energies and a small explicit isospin symmetry breaking,
which accounts for the mass difference between proton and neutron. The
integrability properties of the BPS Skyrme model allow, in fact, for an
analytical calculation of all contributions, which may then be compared with
the semi-empirical mass formula. We find that for heavier nuclei, where the
model is expected to be more accurate on theoretical grounds, the resulting
binding energies are already in excellent agreement with their physical values.
This result provides further strong evidence for the viability of the BPS
Skyrme model as a distinguished starting point and lowest order approximation
for the detailed quantitative investigation of nuclear and hadron physics.


title: Fermions, Wigs, and Attractors

abstract:
  We compute the modifications to the attractor mechanism due to fermionic
corrections. In N=2, D=4 supergravity, at the fourth order, we find a new
contribution to the horizon values of the scalar fields of the vector
multiplets.