title:
Near-infrared H2 and Continuum Survey of Extended Green Objects. II.
  Complete Census for the Northern Galactic Plane

abstract:
  We discuss 94 Extended Green Objects (EGOs) in the northern Galactic plane
cataloged by Cyganowski et al, based on near-infrared narrowband H2 (2.122
{\mu}m and continuum observations from the United Kingdom Infrared Telescope.
This data set is three times larger than our previous study, and is unbiased by
preselection. As discussed in the previous paper, the morphologies of the 4.5
{\mu}m emission generally resemble those of the near-infrared continuum, but
are different from those of the H2 emission. Of our sample, only 28% of EGOs
with H2 emission show similar morphologies between 4.5 {\mu}m and H2 emission.
These results suggest that the 4.5 {\mu}m emission mainly comes from scattered
continuum from the embedded young stellar object (YSO), and partially from H2
emission. About half of EGOs are associated with H2 outflows, if the H2 outflow
incompleteness is considered. The H2 outflow detection rate for EGOs with
K-band detections (61%) is significantly higher than for those without K-band
detections (36%). This difference may be due to the fact that both H2 and
K-band emissions are associated with outflows, i.e., H2 emission and K-band
continuum are associated with shocks and outflow cavities, respectively. We
also compared the correlation between the H2 outflows and Class I 44 GHz
methanol masers from literature. The methanol masers can be located upstream or
downstream of the H2 outflows and some bright H2 spots or outflows are not
associated with methanol masers, suggesting that methanol masers and H2
emission trace different excitation conditions.


title: Freudenthal ranks: GHZ vs. W

abstract:
  The Hilbert space of three-qubit pure states may be identified with a
Freudenthal triple system. Every state has an unique \emph{Freudenthal rank}
ranging from 1 to 4, which is determined by a set of automorphism group
covariants. It is shown here that the optimal success rates for winning a
three-player non-local game, varying over all local strategies, are strictly
ordered by the Freudenthal rank of the shared three-qubit resource.


title: Signatures of particle decay in 21 cm absorptions from first minihalos

abstract:
  The imprint of decaying dark matter (DM) particles in characteristics of the
"21 cm fores" -- absorptions in 21 cm from minihalos in spectra of distant
radio-loud sources -- is considered within a 1D self-consistent hydrodynamic
description of minihalos from their turnaround point to virialization. The most
pronounced influence of decaying DM on evolution of minihalos is found in the
mass range $M=10^5-10^6\msun$, for which unstable DM with the current upper
limit of the ionization rate $\xi_{L} = 0.59\times 10^{-25}$ s$^{-1}$ depresses
21 cm optical depth by an order of magnitude compared to the standard
recombination scenario. Even rather a modest ionization $\xi \sim 0.3\xi_L$
practically "erases" absorption features and results in a considerable decrease
(by factor of more than 2.5) of the number of strong ($W_\nu^{obs} \simgt 0.3$
kHz at $z\simeq 10$) absorptions. At such circumstances broad-band observations
are to be more suitable for inferring physical conditions of the absorbing gas.
X-ray photons from stellar activity of initial episodes of star formation can
compete the contribution from decaying DM only at $z<10$. Therefore, when
observed the 21 cm signal will allow to follow evolution of decaying DM
particles in the redshift range $z=10-15$. Contrary, in case of non-detection
of the 21 cm signal in the frequency range $\nu<140$ MHz a lower limit on the
ionization rate from decaying dark matter can be established.


title:
Graded decomposition numbers of Ariki-Koike algebras for blocks of small
  weight

abstract:
  We present some blocks of Ariki-Koike algebras $\mathcal{H}_{n,r}$ for which
the decomposition matrices are independent of the characteristic of the
underlying field. We complete the description of the graded decomposition
numbers for blocks of Ariki-Koike algebras of weight at most two, which
consists of analysing the indecomposable core blocks at level $r = 3$, and give
a closed formula for the decomposition numbers in this case.


title:
Low-latitude coronal holes, decaying active regions and global coronal
  magnetic structure

abstract:
  We study the relationship between decaying active region magnetic fields,
coronal holes and the global coronal magnetic structure using Global
Oscillations Network Group (GONG) synoptic magnetograms, Solar Terrestrial
RElations Observatory (STEREO) extreme ultra-violet (EUV) synoptic maps and
coronal potential-field source-surface (PFSS) models. We analyze 14 decaying
regions and associated coronal holes occurring between early 2007 and late
2010, four from cycle 23 and 10 from cycle 24. We investigate the relationship
between asymmetries in active regions' positive and negative magnetic
intensities, asymmetric magnetic decay rates, flux imbalances, global field
structure and coronal hole formation. Whereas new emerging active regions
caused changes in the large-scale coronal field, the coronal fields of the 14
decaying active regions only opened under the condition that the global coronal
structure remained almost unchanged. This was because the dominant
slowly-varying, low-order multipoles prevented opposing-polarity fields from
opening and the remnant active-region flux preserved the regions' low-order
multipole moments long after the regions had decayed. Thus the polarity of each
coronal hole necessarily matched the polar field on the side of the streamer
belt where the corresponding active region decayed. For magnetically isolated
active regions initially located within the streamer belt, the more intense
polarity generally survived to form the hole. For non-isolated regions, flux
imbalance and topological asymmetry prompted the opposite to occur in some
cases.


title: Mean Field Games and Systemic Risk

abstract:
  We propose a simple model of inter-bank borrowing and lending where the
evolution of the log-monetary reserves of $N$ banks is described by a system of
diffusion processes coupled through their drifts in such a way that stability
of the system depends on the rate of inter-bank borrowing and lending. Systemic
risk is characterized by a large number of banks reaching a default threshold
by a given time horizon.
  Our model incorporates a game feature where each bank controls its rate of
borrowing/lending to a central bank. The optimization reflects the desire of
each bank to borrow from the central bank when its monetary reserve falls below
a critical level or lend if it rises above this critical level which is chosen
here as the average monetary reserve. Borrowing from or lending to the central
bank is also subject to a quadratic cost at a rate which can be fixed by the
regulator. We solve explicitly for Nash equilibria with finitely many players,
and we show that in this model the central bank acts as a clearing house,
adding liquidity to the system without affecting its systemic risk. We also
study the corresponding Mean Field Game in the limit of large number of banks
in the presence of a common noise.


title:
Penalization method for a nonlinear Neumann PDE via weak solutions of
  reflected SDEs

abstract:
  In this paper we prove an approximation result for the viscosity solution of
a system of semi-linear partial differential equations with continuous
coefficients and nonlinear Neumann boundary condition. The approximation we use
is based on a penalization method and our approach is probabilistic. We prove
the weak uniqueness of the solution for the reflected stochastic differential
equation and we approximate it (in law) by a sequence of solutions of
stochastic differential equations with penalized terms. Using then a suitable
generalized backward stochastic differential equation and the uniqueness of the
reflected stochastic differential equation, we prove the existence of a
continuous function, given by a probabilistic representation, which is a
viscosity solution of the considered partial differential equation. In
addition, this solution is approximated by solutions of penalized partial
differential equations.


title: Pair tunneling of two atoms out of a trap

abstract:
  A simple theory for the tunneling of two cold atoms out of a trap in the
presence of an attractive contact force is developed. Two competing decay
channels, respectively for single-atom and bound-pair tunneling, contribute
independently to the decay law of the mean atom number in the trap. The
single-atom tunneling rate is obtained through the quasiparticle wave function
formalism. For pair tunneling an effective equation for the center-of-mass
motion is derived, so the calculation of the corresponding tunneling rate is
again reduced to a simpler one-body problem. The predicted dependence of
tunneling rates on the interaction strength qualitatively agrees with a recent
measurement of the two-atom decay time [G. Zuern, A. N. Wenz, S. Murmann, T.
Lompe, and S. Jochim, arXiv:1307.5153].


title: Observables and Microscopic Entropy of Higher Spin Black Holes

abstract:
  In the context of recently proposed holographic dualities between higher spin
theories in AdS3 and 1+1-dimensional CFTs with W-symmetry algebras, we revisit
the definition of higher spin black hole thermodynamics and the dictionary
between bulk fields and dual CFT operators. We build a canonical formalism
based on three ingredients: a gauge-invariant definition of conserved charges
and chemical potentials in the presence of higher spin black holes, a canonical
definition of entropy in the bulk, and a bulk-to-boundary dictionary aligned
with the asymptotic symmetry algebra. We show that our canonical formalism
shares the same formal structure as the so-called holomorphic formalism, but
differs in the definition of charges and chemical potentials and in the
bulk-to-boundary dictionary. Most importantly, we show that it admits a
consistent CFT interpretation. We discuss the spin-2 and spin-3 cases in detail
and generalize our construction to theories based on the hs[\lambda] algebra,
and on the sl(N,R) algebra for any choice of sl(2,R) embedding.


title: A linear bound on the Manickam-Miklos-Singhi Conjecture

abstract:
  Suppose that we have a set of numbers x_1, ..., x_n which have nonnegative
sum. How many subsets of k numbers from {x_1, ..., x_n} must have nonnegative
sum? Manickam, Miklos, and Singhi conjectured that for n at least 4k the answer
is (n-1 \choose k-1). This conjecture is known to hold when n is large compared
to k. The best known bounds are due to Alon, Huang, and Sudakov who proved the
conjecture when n > 33k^2. In this paper we improve this bound by showing that
there is a constant C such that the conjecture holds when n > Ck.


title: Quantum Black Holes, Elliptic Genera and Spectral Partition Functions

abstract:
  We study M-theory and D-brane quantum partition functions for microscopic
black hole ensembles within the context of the AdS/CFT correspondence in terms
of highest weight representations of infinite-dimensional Lie algebras,
elliptic genera, and Hilbert schemes, and describe their relations to elliptic
modular forms. The common feature in our examples lie in the modular properties
of the characters of certain representations of the pertinent affine Lie
algebras, and in the role of spectral functions of hyperbolic three-geometry
associated with q-series in the calculation of elliptic genera. We present new
calculations of supergravity elliptic genera on local Calabi-Yau threefolds in
terms of BPS invariants and spectral functions, and also of equivariant D-brane
elliptic genera on generic toric singularities. We use these examples to
conjecture a link between the black hole partition functions and elliptic
cohomology.


title:
The GALEX Arecibo SDSS Survey VII: The Bivariate Neutral
  Hydrogen-Stellar Mass Function for Massive Galaxies

abstract:
  We present the bivariate neutral atomic hydrogen (HI)---stellar mass function
(HISMF) (phi(M_HI, M_*)) for massive (log M_*/M_sun > 10) galaxies derived from
a sample of 480 local (0.025 < z < 0.050) galaxies observed in HI at Arecibo as
part of the GALEX Arecibo SDSS Survey (GASS). We fit six different models to
the HISMF and find that a Schechter function that extends down to a 1% HI gas
fraction, with an additional fractional contribution below that limit, is the
best parametrization of the HISMF. We calculate Omega_{HI, M_* >10^10} and find
that massive galaxies contribute 41% of the HI density in the local universe.
In addition to the binned HISMF we derive a continuous bivariate fit, which
reveals that the Schechter parameters only vary weakly with stellar mass:
M_HI^*, the characteristic HI mass, scales as M_*^0.39, alpha, the slope of the
HISMF at moderate HI masses, scales as M_*^0.07, and f, the fraction of
galaxies with HI gas fraction greater than 1%, scales as M_*^-0.24. The
variation of f with stellar mass should be a strong constraint for numerical
simulations. To understand the physical mechanisms that produce the shape of
the HISMF we redefine the parameters of the Schechter function as explicit
functions of stellar mass and star formation rate to produce a trivariate fit.
This analysis reveals strong trends with SFR. While M_HI^* varies weakly with
stellar mass and SFR, alpha is a stronger function of both stellar mass and
especially star formation rate. The HISMF is a crucial tool that can be used to
constrain cosmological galaxy simulations, test observational predictions of
the HI content of populations of galaxies, and identify galaxies whose
properties deviate from average trends.


title:
Multi-terminal Thermoelectric Transport in a Magnetic Field: Bounds on
  Onsager Coefficients and Efficiency

abstract:
  Thermoelectric transport involving an arbitrary number of terminals is
discussed in the presence of a magnetic field breaking time-reversal symmetry
within the linear response regime using the Landauer-B\"uttiker formalism. We
derive a universal bound on the Onsager coefficients that depends only on the
number of terminals. This bound implies bounds on the efficiency and on
efficiency at maximum power for heat engines and refrigerators. For isothermal
engines pumping particles and for absorption refrigerators these bounds become
independent even of the number of terminals. On a technical level, these
results follow from an original algebraic analysis of the asymmetry index of
doubly substochastic matrices and their Schur complements.


title: Amplified Fermion Production from Overpopulated Bose Fields

abstract:
  We study the real-time dynamics of fermions coupled to scalar fields in a
linear sigma model, which is often employed in the context of preheating after
inflation or as a low-energy effective model for quantum chromodynamics. We
find a dramatic amplification of fermion production in the presence of highly
occupied bosonic quanta for weak as well as strong couplings. For this we
consider the range of validity of different methods: lattice simulations with
male/female fermions, the mode functions approach and the quantum 2PI effective
action with its associated kinetic theory. For strongly coupled fermions we
find a rapid approach to a Fermi-Dirac distribution with time-dependent
temperature and chemical potential parameters, while the bosons are still far
from equilibrium.


title: Cardano v Tartaglia: The Great Feud Goes Supernatural

abstract:
  Many of the stories surrounding the famous sixteenth century feud between
Girolamo Cardano and Niccolo Tartaglia are completely unsupported by the
historical record. In particular, stories that have Tartaglia aiding and
abetting Cardano's arrest for heresy are chronologically impossible.


title:
Event-by-event Hydrodynamic Simulations for Relativistic Heavy-ion
  Collisions

abstract:
  In this thesis, I show my Ph.D. work on event-by-event hydrodynamic
simulations for relativistic heavy-ion collision. I show that event-by-event
hydrodynamic simulations have become an indispensable tool for studying
relativistic heavy-ion collisions and how it can be used to explain many
phenomena. Different chapters focus on different topics; it mainly includes:
Chap 2: comparison between single-shot hydrodynamics event-by-event
hydrodynamic simulations. Chap 3: using the elliptic and triangular flow data
measured by the ALICE collaboration at the LHC to constrain initial condition
models. Chap 4: study on correlations between event-plane angles. Chap 5: how
resonance decay calculation can be speed up by a factor of 10. Chap 6: study on
fluctuations of event planes angle {\Psi}n(pT) and their theoretical and
experimental consequences. Chap 7: sampling particles according to the
Cooper-Frye formula.


title: On meteors, earthworms and WIMPs

abstract:
  We study a model of mass redistribution on a finite graph. We address the
questions of convergence to equilibrium and the rate of convergence. We present
theorems on the distribution of empty sites and the distribution of mass at a
fixed vertex. These distributions are related to random permutations with
certain peak sets.


title: Evolution of the Magnetic Field in Accreting Neutron Stars

abstract:
  In this thesis we address the question of {\em the evolution of the magnetic
field in neutron stars}. There has been sufficient observational indication
suggesting a causal connection between the binary history of neutron stars and
the evolution of their magnetic field. In particular, it is believed that the
generation of the low-field millisecond pulsars is a consequence of the
processing of normal high-field neutron stars in binary systems. Therefore, in
this thesis we try to understand the mechanism of field evolution in neutron
stars that are members of binary systems with an aim to understand the problem
of millisecond pulsar generation. To this end we have looked at four related
problems as described below : 1. the effect of diamagnetic screening on the
final field of a neutron star accreting material from its binary companion; 2.
evolution of magnetic flux located in the crust of an accreting neutron star;
3. application of the above-mentioned model to real systems and a comparison
with observations; 4. an investigation into the consequences of magnetic flux
being initially located in the core of the star and its observational
implications.


title: PHENIX Experiment Results from the RHIC Beam Energy Scan Program

abstract:
  The PHENIX Experiment at RHIC has conducted a beam energy scan at several
collision energies in order to search for signatures of the QCD critical point
and the onset of deconfinement. PHENIX has conducted measurements of transverse
energy production, muliplicity fluctuations, the skewness and kurtosis of net
charge distributions, Hanbury-Brown Twiss correlations, charged hadron flow,
and energy loss. The data analyzed to date show no significant indications of
the presence of the critical point.


title:
Coherence phenomena between initial and final state radiation in a dense
  QCD medium

abstract:
  In this work we investigate medium modifications to the interference pattern
between initial and final state radiation. We compute single gluon production
off a highly energetic parton that undergoes a hard scattering and subsequently
crosses a dense QCD medium of finite size. We extend our previous studies
obtained at first order in opacity by providing general results for multiple
soft scatterings and their specific formulation within the harmonic oscillator
approximation. We show that there is a gradual onset of decoherence between the
initial and final state radiation due to multiple scatterings, that opens the
phase space for large angle emissions. By examining the multiplicity of
produced gluons, we observe a potentially large double logarithmic enhancement
for dense media and small opening angles. This result points to a possible
modification of the evolution equations due to a QCD medium of finite size. We
briefly comment on the phenomenological consequences of this setup in
high-energy nuclear collisions.


title: On the Arithmetic determination of the trace

abstract:
  Let $K$ be a number field, which is tame and non totally real. In this
article we give a numerical criterion, depending only on the ramification
behavior of ramified primes in $K$, to decide whether or not the integral trace
of $K$ is isometric to the integral trace of another number field $L$. As a
byproduct of our proofs here, and in contrast with our previous results for
cubic fields of positive discriminant, we show that for cubic fields of
negative discriminant isometry between integral traces is equivalent to
equality of discriminants.


title:
Finite-State Markov Modeling of Leaky Waveguide Channels in
  Communication-based Train Control (CBTC) Systems

abstract:
  Leaky waveguide has been adopted in communication based train control (CBTC)
systems, as it can significantly enhance railway network efficiency, safety and
capacity. Since CBTC systems have high requirements for the train ground
communications, modeling the leaky waveguide channels is very important to
design the wireless networks and evaluate the performance of CBTC systems. In
the letter, we develop a finite-state Markov channel (FSMC) model for leaky
waveguide channels in CBTC systems based on real field channel measurements
obtained from a business operating subway line. The proposed FSMC channel model
takes train locations into account to have a more accurate channel model. The
overall leaky waveguide is divided into intervals, and an FSMC model is applied
in each interval. The accuracy of the proposed FSMC model is illustrated by the
simulation results generated from the model and the real field measurement
results.


title:
Pressure dependent relaxation in the photo-excited Mott insulator
  ETF2TCNQ: Influence of hopping and correlations on quasiparticle
  recombination rates

abstract:
  Femtosecond relaxation of photo-excited quasiparticles in the one dimensional
Mott insulator ET-F2TCNQ are measured as a function of external pressure, which
is used to tune the electronic structure. By fitting the static optical
properties and measuring femtosecond decay times at each pressure value, we
correlate the relaxation rates with the electronic bandwidth t and on the
intersite correlation energy V. The scaling of relaxation times with
microscopic parameters is different than for metals and semiconductors. The
competition between localization and delocalization of the Mott-Hubbard exciton
dictates the efficiency of the decay, as exposed by a fit based on the solution
of the time-dependent extended Hubbard Hamiltonian.


title:
Ticks, Deer, Mice, and a Touch of Sensitivity: A Recipe for Controlling
  Lyme Disease

abstract:
  Borrelia burgdorferi sensu stricto is a bacterial spirochete prevalent in the
Northeastern United States that causes Lyme disease. Lyme disease is the most
common arthropod-borne disease in the United States; affecting mice, deer,
humans and other mammals. The disease is spread by Ixodes Scapularis, a species
of tick whose primary food source are deer and mice. Reducing the population of
ticks feeding on both large and small mammals below some critical threshold can
decrease the prevalence of Lyme disease among humans. A simplified,
six-dimensional Susceptible-Infected, SI, model is used to capture the
mice-deer-tick dynamics while considering the impact of varying
population-specific death rates on infected population size. We analyzed the
stability of the models two equilibria, the unstable disease free equilibrium
and the endemic equilibrium. Static forward sensitivity analysis is conducted
on the basic reproduction number and the endemic equilibrium. A dynamic
approach was explored to observe change in the sensitivity of the death rates
over time. These analyses were conducted to determine the efficacy of changing
death rates in order to reduce prevalence of Lyme disease.


title: Econophysics Research in India in the last two Decades

abstract:
  We discuss here researches on econophysics done from India in the last two
decades. The term `econophysics' was formally coined in India (Kolkata) in
1995. Since then many research papers, books, reviews, etc. have been written
by scientists. Many institutions are now involved in this research field and
many conferences are being organized there. In this article we give an account
(of papers, books, reviews, papers in proceedings volumes etc.) of this
research from India.


title:
Compatible systems of symplectic Galois representations and the inverse
  Galois problem III. Automorphic construction of compatible systems with
  suitable local properties

abstract:
  This article is the third and last part of a series of three articles about
compatible systems of symplectic Galois representations and applications to the
inverse Galois problem.
  This part proves the following new result for the inverse Galois problem for
symplectic groups. For any even positive integer n and any positive integer d,
PSp_n(F_{l^d}) or PGSp_n(F_{l^d}) occurs as a Galois group over the rational
numbers for a positive density set of primes l.
  The result is obtained by showing the existence of a regular, algebraic,
self-dual, cuspidal automorphic representation of GL_n(A_Q) with local types
chosen so as to obtain a compatible system of Galois representations to which
the results from Part II of this series apply.


title:
Non-empirical Generalized Gradient Approximation Free Energy Functional
  for Orbital-free Simulations

abstract:
  We report the first wholly non-empirical generalized gradient approximation,
non-interacting free energy functional for orbital-free density functional
theory and use that new functional to provide forces for finite-temperature
molecular dynamics simulations in the warm dense matter (WDM) regime The new
functional provides good-to-excellent agreement with reference Kohn-Sham
calculations under WDM conditions at a minuscule fraction of the computational
cost of corresponding orbital-based simulations.


title:
NLO QCD corrections to diphoton plus jet production through graviton
  exchange

abstract:
  We present the NLO QCD corrections to the production of a photon pair in
association with one jet, where the photons are stemming from graviton decay,
within models of large extra dimensions. Our results for the loop amplitudes
are produced with the program GOSAM for automated one-loop calculations. We
show distributions for several observables for 4, 5 and 6 extra dimensions and
demonstrate that the differential K-factors are far from being uniform.


title: Evaluating Astronomy Literacy of the General Public

abstract:
  A scientifically literate society is important for many different reasons,
some of which include democratic and scientific topics. This study was
performed in order to identify topics in astronomy and science in general that
may not be well understood by the general public. Approximately 1,000 adults at
a popular science museum in Philadelphia, PA completed True-False survey
questions about basic astronomy concepts. The participants were also asked to
provide their age, gender, and highest degree obtained. Although 93 +/- 0.8% of
the participants correctly answered that scientists can calculate the age of
the Earth, only 58 +/- 2% provided the correct response that scientists can
calculate the age of the Universe. Some participants (30 +/- 1%) responded that
scientists have found life on Mars. Females scored an average total score of 78
+/- 2%, whereas males scored an average 85 +/- 1%. Participants with an age of
56 and over had an average score of 78 +/- 4% compared to participants under
the age of 56 that were found to have an average score of 82 +/- 2%. Lastly,
participants' highest degree obtained scaled with number of correct responses,
with graduate level degree earners providing the largest amount of correct
responses and an average score of 86 +/- 2%.


title:
A New Mattress Development Based on Pressure Sensors for Body-contouring
  Uniform Support

abstract:
  For getting good sleep quality, an improved approach of new mattress
development based on the pressure sensors for body-contouring uniform support
is proposed in this paper. This method solved the problems of innerspring
mattresses that cannot allow body-contouring uniform support, and foam
mattresses that cannot provide everybody equal comfort from the same mattress.
By the buried pressure sensor array and actuator array in foam layer of a
mattress, both are connected to a controller to generate the pressure
distribution mapping of a human body on the mattress, then from the data of
this mapping, some of the actuators are driven up or down by the controller to
generate a body-contouring uniform support. By the aid of mathematical
morphology algorithms, user can also choose a different support mode by another
wireless controller with touch-screen to accommodate personal favorite firmness
of the mattress and to take his tensed mood and pressure off with good sleep
until daylight. Moreover, some other homecare functions, such as temperature
measurement, sleep on posture correction and fall down prevention, can approach
by additional hardware and software as user requirement in the future.


title:
Mass of a lattice polaron from extended Holstein model using Yukawa
  potential

abstract:
  Renormalization of the mass of an electron is studied within the framework of
the Extended Holstein model at strong coupling regime and nonadiabatic limit.
In order to take into account an effect of screening of an electron-phonon
interaction on a polaron it is assumed that the electron-phonon interaction
potential has the Yukawa form and screening of the electron-phonon interaction
is due to the presence of other electrons in a lattice. The forces are derived
from the Yukawa type electron-phonon interaction potential. It is emphasized
that the early considered screened force of
Refs.\cite{kor-giant,spencer,hague-etal,hague-kor} is a particular case of the
force deduced from the Yukawa potential and is approximately valid at large
screening radiuses compared to the distances under consideration. The Extended
Holstein polaron with the Yukawa type potential is found to be a more mobile
than polaron studied in early works at the same screening regime.


title: Notes on a new construction of hyperkahler metrics

abstract:
  We review a construction of hyperkahler metrics proposed in joint work of
Davide Gaiotto, Greg Moore and the author. A key ingredient in this
construction is a collection of integer "DT invariants" obeying the
wall-crossing formula of Kontsevich-Soibelman.


title:
Cosmological model dependence of the galaxy luminosity function:
  far-infrared results in the Lemaitre-Tolman-Bondi model

abstract:
  This is the first paper of a series aiming at investigating galaxy formation
and evolution in the giant-void class of the Lemaitre-Tolman-Bondi (LTB) models
that best fits current cosmological observations. Here we investigate the
Luminosity Function (LF) methodology, and how its estimates would be affected
by a change on the cosmological model assumed in its computation. Are the
current observational constraints on the allowed Cosmology enough to yield
robust LF results? We use the far-infrared source catalogues built on the
observations performed with the Herschel/PACS instrument, and selected as part
of the PACS evolutionary probe (PEP) survey. Schechter profiles are obtained in
redshift bins up to z approximately 4, assuming comoving volumes in both the
standard model, that is, Friedmann-Lemaitre-Robertson-Walker metric with a
perfect fluid energy-momentum tensor, and non-homogeneous LTB dust models,
parametrized to fit the current combination of results stemming from the
observations of supernovae Ia, the cosmic microwave background, and baryonic
acoustic oscillations. We find that the luminosity functions computed assuming
both the standard model and LTB void models show in general good agreement.
However, the faint-end slope in the void models shows a significant departure
from the standard model up to redshift 0.4. We demonstrate that this result is
not artificially caused by the used LF estimator which turns out to be robust
under the differences in matter-energy density profiles of the models. The
differences found in the LF slopes at the faint end are due to variation in the
luminosities of the sources, which depend on the geometrical part of the model.
It follows that either the standard model is over-estimating the number density
of faint sources or the void models are under-estimating it.


title: Interplay of Superconductivity and Spin-Dependent Disorder

abstract:
  The finite temperature phase diagram for the 2D attractive fermion Hubbard
model with spin-dependent disorder is considered within Bogoliubov-de Gennes
mean field theory. Three types of disorder are studied. In the first, only one
species is coupled to a random site energy; in the second, the two species both
move in random site energy landscapes which are of the same amplitude, but
different realizations; and finally, in the third, the disorder is in the
hopping rather than the site energy. For all three cases we find that, unlike
the case of spin-symmetric randomness, where the energy gap and average order
parameter do not vanish as the disorder strength increases, a critical disorder
strength exists separating distinct phases. In fact, the energy gap and the
average order parameter vanish at distinct transitions, $V_{c}^{\rm gap}$ and
$V_{c}^{\rm op}$, allowing for a gapless superconducting (gSC) phase. The gSC
phase becomes smaller with increasing temperature, until it vanishes at a
temperature $T^{\ast}$.


title:
Superconducting specific heat jump $\Delta C_{\rm el} \propto T_c^\beta
  \ (\beta \approx 2)$ for K$_{1-x}$Na$_x$Fe$_2$As$_2$

abstract:
  We present a systematic study of the electronic specific heat jump ($\Delta
C_{\rm el}$) at the superconducting transition temperature $T_c$ of
K$_{1-x}$Na$_x$Fe$_2$As$_2$. Both $T_c$ and $\Delta C_{\rm el}$ monotonously
decrease with increasing $x$. The specific heat jump scales approximately with
a power-law, $\Delta C_{\rm el} \propto T_c^{\beta}$, with $\beta \approx 2$
determined by the impurity scattering rate, in contrast to most iron-pnictide
superconductors, where the remarkable Bud'ko-Ni-Canfield (BNC) scaling $\Delta
C_{\rm el} \propto T^3$ has been found. Both the $T$ dependence of $C_{\rm
el}(T)$ in the superconducting state and the nearly quadratic scaling of
$\Delta C_{\rm el}$ at $T_c$ are well described by the Eliashberg-theory for a
two-band $d$-wave superconductor with weak pair-breaking due to nonmagnetic
impurities. The disorder induced by the Na substitution significantly
suppresses the small gaps leading to gapless states in the slightly disordered
superconductor, which results in a large observed residual Sommerfeld
coefficient in the superconducting state for $x > 0$.


title: Assessing the quality of a student-generated question repository

abstract:
  We present results from a study that categorizes and assesses the quality of
questions and explanations authored by students, in question repositories
produced as part of the summative assessment in introductory physics courses
over the past two years. Mapping question quality onto the levels in the
cognitive domain of Bloom's taxonomy, we find that students produce questions
of high quality. More than three-quarters of questions fall into categories
beyond simple recall, in contrast to similar studies of student-authored
content in different subject domains. Similarly, the quality of
student-authored explanations for questions was also high, with approximately
60% of all explanations classified as being of high or outstanding quality.
Overall, 75% of questions met combined quality criteria, which we hypothesize
is due in part to the in-class scaffolding activities that we provided for
students ahead of requiring them to author questions.


title: Weierstrass points on Kummer extensions

abstract:
  For Kummer extensions $y^m=f(x)$, we discuss conditions for an integer be a
Weierstrass gap at a place $P$. In the case of totally ramified places, the
conditions will be necessary and sufficient. As a consequence, we extend
independent results of several authors.


title: Screening magnetic fields by a superconducting disk: a simple model

abstract:
  We introduce a simple approach to evaluate the magnetic field distribution
around superconducting samples, based on the London equations; the elementary
variable is the vector potential. This procedure has no adjustable parameters,
only the sample geometry and the London length, $\lambda$, determine the
solution. The calculated field reproduces quantitatively the measured induction
field above MgB$_2$ disks of different diameters, at 20K and for applied fields
lower than 0.4T. The model can be applied if the flux line penetration inside
the sample can be neglected when calculating the induction field distribution
outside the superconductor. Finally we show on a cup-shape geometry how one can
design a magnetic shield satisfying a specific constraint.


title:
Collision and Diffusion in Microwave Breakdown of Nitrogen Gas in and
  around Microgaps

abstract:
  The microwave induced breakdown of N2 gas in microgaps was modeled using the
collision frequency between electrons and neutral molecules and the effective
electric field concept. Low pressure breakdown at the threshold electric field
occurs outside the gap, but at high pressures it is found to occur inside the
microgap with a large threshold breakdown electric field corresponding to a
very large electron oscillation amplitude. Three distinct pressure regimes are
apparent in the microgap breakdown: a low pressure multipactor branch, a
mid-pressure Paschen branch, both of which occur in the space outside the
microgap, and a high pressure diffusion-drift branch, which occurs inside the
microgap. The Paschen and diffusion-drift branches are divided by a sharp
transition and each separately fits the collision frequency model. There is
evidence that considerable electron loss to the microgap faces accompanies the
diffusion-drift branch in microgaps.


title: Energetic Causal Sets

abstract:
  We propose an approach to quantum theory based on the energetic causal sets,
introduced in Cort\^{e}s and Smolin (2013). Fundamental processes are causal
sets whose events carry momentum and energy, which are transmitted along causal
links and conserved at each event. Energetic causal set models differ from
other spacetime-free causal set approaches, e.g. Ref. [2] proposed causal sets
based on quantum information processing systems, and Ref. [3] proposed causal
sets constructed out of standard model particles. Fundamentally there are
amplitudes for causal processes in energetic causal sets, but no space-time. An
embedding of the causal processes in an emergent space-time arises only at the
semiclassical level. Hence, fundamentally there are no commutation relations,
no uncertainty principle and, indeed, no $\hbar$. All that remains of quantum
theory is the relationship between the absolute value squared of complex
amplitudes and probabilities. Consequently, we find that neither locality, nor
non locality, are primary concepts, only causality exists at the fundamental
level.


title:
Spin State Detection and Manipulation and Parity Violation in a Single
  Trapped Ion

abstract:
  Atomic Parity Violation provides the rare opportunity of a low energy window
into possible new fundamental processes at very high mass scales normally
investigated at large high energy accelerators. Precise measurements on atomic
systems are currently the most sensitive probes of many kinds of new physics,
and complement high energy experiments. Present atomic experiments are
beginning to reach their limits of precision due to either sensitivity,
systematics or atomic structure uncertainties. An experiment in a single
trapped Barium ion can improve on all of these difficulties. This experiment
uses methods to precisely manipulate and detect the spin state of a single ion
in order to measure a parity induced splitting of the ground state magnetic
sublevels in externally applied laser fields. The same methods can be used to
provide precise measurements of more conventional atomic structure parameters.


title: Quantum nondemolition detection of a propagating microwave photon

abstract:
  The ability to nondestructively detect the presence of a single, traveling
photon has been a long-standing goal in optics, with applications in quantum
information and measurement. Realising such a detector is complicated by the
fact that photon-photon interactions are typically very weak. At microwave
frequencies, very strong effective photon-photon interactions in a waveguide
have recently been demonstrated. Here we show how this type of interaction can
be used to realize a quantum nondemolition measurement of a single propagating
microwave photon. The scheme we propose uses a chain of solid-state 3-level
systems (transmons), cascaded through circulators which suppress photon
backscattering. Our theoretical analysis shows that microwave-photon detection
with fidelity around 90% can be realized with existing technologies.


title: New Production Mechanism for Heavy Neutrinos at the LHC

abstract:
  We study a new production mechanism for heavy neutrinos at the LHC, which
dominates over the usually considered $s$-channel $W$-exchange diagram for
heavy-neutrino masses larger than 100 - 200 GeV. The new mechanism is
infrared-enhanced by $t$-channel $W\gamma$-fusion processes. This has important
implications for experimental tests of the seesaw mechanism of neutrino masses,
and in particular, for the ongoing heavy neutrino searches at the LHC. We find
that the direct collider limits on the light-to-heavy neutrino mixing can be
significantly improved, when this new production channel is properly taken into
account. The scope of this new mechanism can equally well be extended to other
exotic searches at the LHC.


title:
Sensitivity of atmospheric neutrinos in Super-Kamiokande to Lorentz
  violation

abstract:
  This talk, given at CPT'13, showed Super-Kamiokande atmospheric-neutrino
Monte Carlo sensitivity to Lorentz-violation effects using the perturbative
model derived from the Standard-Model Extension.


title: Tuza's Conjecture for Graphs of Maximum Average Degree Less Than 7

abstract:
  Tuza's Conjecture states that if a graph $G$ does not contain more than $k$
edge-disjoint triangles, then some set of at most $2k$ edges meets all
triangles of $G$. We prove Tuza's Conjecture for all graphs $G$ having no
subgraph with average degree at least $7$. As a key tool in the proof, we
introduce a notion of reducible sets for Tuza's Conjecture; these are
substructures which cannot occur in a minimal counterexample to Tuza's
Conjecture. We also introduce weak K\"onig--Egerv\'ary graphs, a generalization
of the well-studied K\"onig--Egerv\'ary graphs.


title:
Security limitation on a class of device-independent quantum key
  distribution

abstract:
  Recently there were many proposals on device-independent (DI) quantum key
distribution protocol whose security is based on the violation of the
Clauser-Horne-Shimony-Holt inequality. However, as a statistical law, a certain
extent of fluctuation has to be allowed. We show that the eavesdropper can make
use of this property to obtain a remarkable part of the secret key by replacing
some of the DI nonlocal boxes with local ones. On the contrary, the same
cheating strategy does not apply to the device-dependent (DD) version of the
protocol. Thus such kind of DI protocol is less secure than its DD counterpart.


title: Classifying Orders in the Sklyanin Algebra

abstract:
  One of the major open problems in noncommutative algebraic geometry is the
classification of noncommutative surfaces, and this paper resolves a
significant case of this problem. Specifically, let S denote the 3-dimensional
Sklyanin algebra over an algebraically closed field k and assume that S is not
a finite module over its centre. (This algebra corresponds to a generic
noncommutative P^2.) Let A be any connected graded k-algebra that is contained
in and has the same quotient ring as a Veronese ring S^(3n). Then we give a
reasonably complete description of the structure of A. This is most
satisfactory when A is a maximal order, in which case we prove, subject to a
minor technical condition, that A is a noncommutative blowup of S^(3n) at a
(possibly non-effective) divisor on the associated elliptic curve E. It follows
that A has surprisingly pleasant properties; for example it is automatically
noetherian, indeed strongly noetherian, and has a dualizing complex.


title: Toeplitzness of composition operators in several variables

abstract:
  Motivated by the work of Nazarov and Shapiro on the unit disk, we study
asymptotic Toeplitzness of composition operators on the Hardy space of the unit
sphere in C^n. We extend some of their results but we also show that new
phenomena appear in higher dimensions.


title:
Tunable Coupling of Two-Dimensional Superconductors in Bilayer SrTiO3
  Heterostructures

abstract:
  Interlayer coupling effects between high mobility two-dimensional
superconductors are studied in bilayer delta-doped SrTiO3 heterostructures. By
tuning the undoped SrTiO3 spacer layer between the dopant planes, clear tunable
coupling is demonstrated in the variation of the sheet carrier density, Hall
mobility, superconducting transition temperature, and the temperature- and
angle-dependences of the superconducting upper critical field. Systematic
variation is found between one effective (merged) two-dimensional
superconductor to two decoupled two-dimensional superconductors. In the
intermediate coupled regime, a crossover is observed due to coupling arising
from inter-sub-band interactions.


title: Noncommutative Blowups of Elliptic Algebras

abstract:
  We develop a ring-theoretic approach for blowing up many noncommutative
projective surfaces. Let T be an elliptic algebra (meaning that, for some
central element g of degree 1, T/gT is a twisted homogeneous coordinate ring of
an elliptic curve E at an infinite order automorphism). Given an effective
divisor d on E whose degree is not too big, we construct a blowup T(d) of T at
d and show that it is also an elliptic algebra. Consequently it has many good
properties: for example, it is strongly noetherian, Auslander-Gorenstein, and
has a balanced dualizing complex. We also show that the ideal structure of T(d)
is quite rigid. Our results generalise those of the first author. In the
companion paper "Classifying Orders in the Sklyanin Algebra", we apply our
results to classify orders in (a Veronese subalgebra of) a generic cubic or
quadratic Sklyanin algebra.


title:
Exact results for boundaries and domain walls in 2d supersymmetric
  theories

abstract:
  We apply supersymmetric localization to N=(2,2) gauged linear sigma models on
a hemisphere, with boundary conditions, i.e., D-branes, preserving B-type
supersymmetries. We explain how to compute the hemisphere partition function
for each object in the derived category of equivariant coherent sheaves, and
argue that it depends only on its K theory class. The hemisphere partition
function computes exactly the central charge of the D-brane, completing the
well-known formula obtained by an anomaly inflow argument. We also formulate
supersymmetric domain walls as D-branes in the product of two theories. In
particular 4d line operators bound to a surface operator, corresponding via the
AGT relation to certain defects in Toda CFT's, are constructed as domain walls.
Moreover we exhibit domain walls that realize the sl(2) affine Hecke algebra.


title: Coding for Random Projections

abstract:
  The method of random projections has become very popular for large-scale
applications in statistical learning, information retrieval, bio-informatics
and other applications. Using a well-designed coding scheme for the projected
data, which determines the number of bits needed for each projected value and
how to allocate these bits, can significantly improve the effectiveness of the
algorithm, in storage cost as well as computational speed. In this paper, we
study a number of simple coding schemes, focusing on the task of similarity
estimation and on an application to training linear classifiers. We demonstrate
that uniform quantization outperforms the standard existing influential method
(Datar et. al. 2004). Indeed, we argue that in many cases coding with just a
small number of bits suffices. Furthermore, we also develop a non-uniform 2-bit
coding scheme that generally performs well in practice, as confirmed by our
experiments on training linear support vector machines (SVM).


title:
Emergent collective phenomena in a mixture of hard shapes through active
  rotation

abstract:
  We investigate collective phenomena with rotationally driven spinners of
concave shape. Each spinner experiences a constant internal torque in either a
clockwise or counterclockwise direction. Although the spinners are modeled as
hard, otherwise non-interacting rigid bodies, we find that their active motion
induces an effective interaction that favors rotation in the same direction.
With increasing density and activity, phase separation occurs via spinodal
decomposition, as well as self-organization into rotating crystals. We observe
the emergence of cooperative, super-diffusive motion along interfaces, which
can transport inactive test particles. Our results demonstrate novel phase
behavior of actively rotated particles that is not possible with linear
propulsion or in non-driven, equilibrium systems of identical hard particles.


title:
Dendritic flux avalanches in Niobium single crystal near critical
  temperature

abstract:
  We report on the observation of dendritic flux avalanches in a large Niobium
single crystal. In contrast to avalanches observed in thin films, they appear
only in a very narrow temperature interval of about a tenth of a Kelvin near
the critical temperature of Nb. At a fixed temperature, we find two sets of
dendritic structures, which differ by the magnetic field required for their
formation and by the maximum distance the dendrites penetrate into the sample.
The effect is caused by dendritic flux penetration into thin superconducting
surface layers formed in the single crystal close to the critical temperature.


title: Noether gauge symmetry approach in quintom cosmology

abstract:
  In literature usual point like symmetries of the Lagrangian have been
introduced to study the symmetries and the structure of the fields. This kind
of Noether symmetry is a subclass of a more general family of symmetries,
called Noether Gauge Symmetries (NGS). Motivated by this mathematical tool, in
this article, we discuss the generalized Noether symmetry of Quintom model of
dark energy, which is a two component fluid model of quintessence and phantom
fields. Our model is a generalization of the Noether symmetries of a single and
multiple components which have been investigated in detail before. We found the
general form of the quintom potential in which the whole dynamical system has a
point like symmetry. We investigated different possible solutions of the system
for diverse family of gauge function. Specially, we discovered two family of
potentials, one corresponds to a free quintessence (phantom) and the second is
in the form of quadratic interaction between two components. These two families
of potential functions are proposed from the symmetry point of view, but in the
quintom models they are used as phenomenological models without clear
mathematical justification. From integrability point of view, we found two
forms of the scale factor: one is power law and second is de-Sitter. Some
cosmological implications of the solutions have been investigated


title:
Topological excitations and the dynamic structure factor of spin liquids
  on the kagome lattice

abstract:
  Recent neutron scattering experiments on the spin-1/2 kagome lattice
antiferromagnet ZnCu3(OH)6Cl2 (Herbertsmithite) provide the first evidence of
fractionalized excitations in a quantum spin liquid state in two spatial
dimensions. In contrast to existing theoretical models of spin liquids, the
measured dynamic structure factor reveals an excitation continuum which is
remarkably flat as a function of frequency and has almost no momentum
dependence along several high-symmetry directions. Here we show that many
experimentally observed features can be explained by the presence of
topological vison excitations in a Z2 spin liquid. These visons form flat bands
on the kagome lattice, and thus act as a momentum sink for spin-carrying
excitations which are probed by neutron scattering. We compute the dynamic
structure factor for two different Z2 spin liquids and find that one of them
describes Herbertsmithite well above a very low energy cutoff.


title:
A Trend Between Cold Debris Disk Temperature and Stellar Type:
  Implications for the Formation and Evolution of Wide-Orbit Planets

abstract:
  Cold debris disks trace the limits of planet formation or migration in the
outer regions of planetary systems, and thus have the potential to answer many
of the outstanding questions in wide-orbit planet formation and evolution. We
characterized the infrared excess spectral energy distributions of 174 cold
debris disks around 546 main-sequence stars observed by both Spitzer IRS and
MIPS. We found a trend between the temperature of the inner edges of cold
debris disks and the stellar type of the stars they orbit. This argues against
the importance of strictly temperature-dependent processes (e.g. non-water ice
lines) in setting the dimensions of cold debris disks. Also, we found no
evidence that delayed stirring causes the trend. The trend may result from
outward planet migration that traces the extent of the primordial
protoplanetary disk, or it may result from planet formation that halts at an
orbital radius limited by the efficiency of core accretion.


title: S-process in low-mass extremely metal-poor stars

abstract:
  Extremely metal-poor low-mass stars experience an ingestion of protons into
the helium-rich layer during the core He-flash, resulting in the production of
neutrons through the reactions
^{12}C(p,\gamma)^{13}N(\beta)^{13}C(\alpha,n)^{16}O. This is a potential site
for the production of s-process elements in extremely metal-poor stars not
occurring in more metal-rich counterparts. Observationally, the signatures of
s-process elements in the two most iron deficient stars observed to date,
HE1327-2326 & HE0107-5240, still await for an explanation. We investigate the
possibility that low-mass EMP stars could be the source of s-process elements
observed in extremely iron deficient stars, either as a result of
self-enrichment or in a binary scenario as the consequence of a mass transfer
episode. We present evolutionary and post-processing s-process calculations of
a 1Msun stellar model with metallicities Z=0, 10^{-8} and 10^{-7}. We assess
the sensitivity of nucleosynthesis results to uncertainties in the input
physics of the stellar models, particularly regarding the details of convective
mixing during the core He-flash. Our models provide the possibility of
explaining the C, O, Sr, and Ba abundance for the star HE0107-5240 as the
result of mass-transfer from a low-mass EMP star. The drawback of our model is
that if mass would be transferred before the primary star enters the AGB phase,
nitrogen would be overproduced and the ^{12}C/^{13}C abundance ratio would be
underproduced in comparison to the observed values. Our results show that
low-mass EMP stars cannot be ruled out as the companion stars that might have
polluted HE1327-2326 & HE0107-5240 and produced the observed s-process pattern.
However, more detailed studies of the core He-flash and the proton ingestion
episode are needed to determine the robustness of our predictions.


title: Probing the nature of the Higgs-gluon coupling

abstract:
  One and two-jet observables of dimension-7 Higgs-gluon coupling operators are
studied as probes of possible deviations from the top-loop induced gluon-Higgs
coupling. We discuss the case of both a scalar as well as a pseudo-scalar Higgs
boson and show that higher order operators can give visible deviations from
Standard Model distribution shapes.


title:
MT2-reconstructed invisible momenta as spin analizers, and an
  application to top polarization

abstract:
  Full event reconstruction is known to be challenging in cases with more than
one undetected final-state particle, such as pair production of two states each
decaying semi-invisibly. On the other hand, full event reconstruction would
allow to access angular distributions sensitive to the spin fractions of the
decaying particles, thereby dissecting their production mechanism. We explore
this possibility in the case of Standard-Model t-tbar production followed by a
leptonic decay of both W bosons, implying two undetected final-state neutrinos.
We estimate the t and tbar momentum vectors event by event using information
extracted from the kinematic variable MT2. The faithfulness of the estimated
momenta to the true momenta is then tested in observables sensitive to top
polarization and t-tbar spin correlations. Our method thereby provides a novel
approach towards the evaluation of these observables, and towards testing
t-tbar production beyond the level of the total cross section. While our
discussion is confined to t-tbar production as a benchmark, the method is
applicable to any process whose decay topology allows to construct MT2.


title: A Search for RR Lyrae Stars in Segue 2 and Segue 3

abstract:
  We present an extensive search for RR Lyrae stars in and around the
ultra-faint Milky Way companions Segue 2 and Segue 3. The former (M_V = -2.5,
Belokurov et al. 2009) appears to be an extremely faint dwarf galaxy companion
of the Milky Way. The latter (M_V = 0.0, Fadely et al. 2011) is among the
faintest star clusters known. We use B and V band time-series imaging obtained
at the WIYN 0.9 meter telescope at Kitt Peak National Observatory to search for
RR Lyrae in these objects. In our Segue 2 observations, we present a previously
unknown fundamental mode (RRab) RR Lyrae star with a period of P_ab = 0.748
days. With this measurement, we revisit the inverse correlation between <P_ab>
and <[Fe/H]> established in the literature for Milky Way dwarf galaxies and
their RR Lyrae. In this context, the long period of Segue 2's RRab star as well
as the known significant spread in metallicity in this dwarf galaxy are
consistent with the observed trend in <P_ab> and <[Fe/H]>. We derive the first
robust distance to Segue 2, using both its RRab star and spectroscopically
confirmed blue horizontal branch stars. Using [Fe/H] = -2.16 and -2.44 dex, we
find d_RRL = 36.6 +2.5/-2.4 and 37.7 +/- 2.7 kpc; assuming [Fe/H] = -2.257 dex,
we find d_BHB = 34.4 +/- 2.6 kpc. Although no RR Lyrae were present in the
Segue 3 field, we found a candidate eclipsing binary star system.


title: Separating astrophysical sources from indirect dark matter signals

abstract:
  Indirect searches for products of dark matter annihilation and decay face the
challenge of identifying an uncertain and subdominant signal in the presence of
uncertain backgrounds. Two valuable approaches to this problem are (1) using
analysis methods which take advantage of different features in the energy
spectrum and angular distribution of the signal and backgrounds, and (2) more
accurate characterization of backgrounds, which allows for more robust
identification of possible signals. These two approaches are complementary and
can be significantly strengthened when used together. I review the status of
indirect searches with gamma rays using two promising targets, the Inner Galaxy
and the Isotropic Gamma-Ray Background. For both targets, uncertainties in the
properties of backgrounds is a major limitation to the sensitivity of indirect
searches. I then highlight approaches which can enhance the sensitivity of
indirect searches using these targets.

categories: astro-ph.HE astro-ph.CO astro-ph.GA hep-ph


title:
Ground state phase diagram of the 2d Bose-Hubbard model with anisotropic
  hopping

abstract:
  We compute the ground state phase diagram of the 2d Bose-Hubbard model with
anisotropic hopping using quantum Monte Carlo simulations, connecting the 1d to
the 2d system. We find that the tip of the lobe lies on a curve controlled by
the 1d limit over the full anisotropy range while the universality class is
always the same as in the isotropic 2d system. This behavior can be derived
analytically from the lowest RG equations and has a form typical for the
underlying Kosterlitz-Thouless transition in 1d. We also compute the phase
boundary of the Mott lobe for strong anisotropy and compare it to the 1d
system. Our calculations shed light on recent cold gas experiments monitoring
the dynamics of an expanding cloud.


title: Limits on Quaoar's Atmosphere

abstract:
  Here we present high cadence photometry taken by the Acquisition Camera on
Gemini South, of a close passage by the $\sim540$ km radius Kuiper Belt Object,
(50000) Quaoar, of a r'=20.2 background star. Observations before and after the
event show that the apparent impact parameter of the event was
$0.019\pm0.004$", corresponding to a close approach of $580\pm120$ km to the
centre of Quaoar. No signatures of occultation by either Quaoar's limb or its
potential atmosphere are detectable in the relative photometry of Quaoar and
the target star, which were unresolved during closest approach. From this
photometry we are able to put constraints on any potential atmosphere Quaoar
might have. Using a Markov chain Monte Carlo and likelihood approach, we place
pressure upper limits on sublimation supported, isothermal atmospheres of pure
N$_2$, CO, and CH$_4$. For N$_2$ and CO, the upper limit surface pressures are
1 and 0.7 $\mu{bar}$ respectively. The surface temperature required for such
low sublimation pressures is $\sim33$ K, much lower than Quaoar's mean
temperature of $\sim44$ K measured by others. We conclude that Quaoar cannot
have an isothermal N$_2$ or CO atmosphere. We cannot eliminate the possibility
of a CH$_4$ atmosphere, but place upper surface pressure and mean temperature
limits of $\sim138$ nbar and $\sim44$ K respectively.


title: The M5-brane action revisited

abstract:
  We construct an alternative form of the M5-brane action in which the
six-dimensional worldvolume is subject to a covariant split into 3+3 directions
by a triplet of auxiliary fields. We consider the relation of this action to
the original form of the M5-brane action and to a Nambu-Poisson 5-brane action
based on the Bagger-Lambert-Gustavsson model with the gauge symmetry of volume
preserving diffeomorphisms


title:
Gluino bounds: Simplified Models vs a Particular SO(10) Model (A
  Snowmass white paper)

abstract:
  We consider the results from the first run of LHC studied in the context of
simplified models and re-interpret them for a particular SO(10) model with a
non-simplified topology. Hadronic searches have been designed to obtain the
best sensitivity for the simplified models. They require multiple b-jets in the
final state. But we show that the bounds obtained from these searches are
weaker in the case of the particular model studied here, since there are fewer
b-jets.


title: Frame Transformations for Fermions

abstract:
  The analog to the Legendre addition theorem is found for half-integral
angular momentum using frame transformations for rotor states.


title: Innovation networks

abstract:
  This paper advances a framework for modeling the component interactions
between cognitive and social aspects of scientific creativity and technological
innovation. Specifically, it aims to characterize Innovation Networks; those
networks that involve the interplay of people, ideas and organizations to
create new, technologically feasible, commercially-realizable products,
processes and organizational structures. The tri-partite framework captures
networks of ideas (Concept Level), people (Individual Level) and social
structures (Social-Organizational Level) and the interactions between these
levels. At the concept level, new ideas are the nodes that are created and
linked, kept open for further investigation or closed if solved by actors at
the individual or organizational levels. At the individual level, the nodes are
actors linked by shared worldviews (based on shared professional, educational,
experiential backgrounds) who are the builders of the concept level. At the
social-organizational level, the nodes are organizations linked by common
efforts on a given project (e.g., a company-university collaboration) that by
virtue of their intellectual property or rules of governance constrain the
actions of individuals (at the Individual Level) or ideas (at the Concept
Level). After describing this framework and its implications we paint a number
of scenarios to flesh out how it can be applied.


title: Constraining the Milky Way Halo Shape Using Thin Streams

abstract:
  Tidal streams are a powerful probe of the Milky Way (MW) potential shape. In
this paper, we introduce a simple test particle method to fit stream data,
using a Markov Chain Monte Carlo technique to marginalise over uncertainties in
the progenitor's orbit and the Milky Way halo shape parameters. Applying it to
mock data of thin streams in the MW halo, we show that, even for very cold
streams, stream-orbit offsets - not modelled in our simple method - introduce
systematic biases in the recovered shape parameters. For the streams that we
consider, and our particular choice of potential parameterisation, these errors
are of order ~20% on the halo flattening parameters. However, larger systematic
errors can arise for more general streams and potentials; such offsets need to
be correctly modelled in order to obtain an unbiased recovery of the underlying
potential.
  Assessing which of the known Milky Way streams are most constraining, we find
NGC 5466 and Pal 5 are the most promising candidates. These form an interesting
pair as their orbital planes are both approximately perpendicular to each other
and to the disc, giving optimal constraints on the MW halo shape. We show that
- while with current data their constraints on potential parameters are poor -
good radial velocity data along the Pal 5 stream will provide constraints on qz
- the flattening perpendicular to the disc. Furthermore, as discussed in a
companion paper, NGC 5466 can provide rather strong constraints on the MW halo
shape parameters, if the tentative evidence for a departure from the smooth
orbit towards its western edge is confirmed.


title: Surprise: Youve got some explaining to do

abstract:
  Why are some events more surprising than others? We propose that events that
are more difficult to explain are those that are more surprising. The two
experiments reported here test the impact of different event outcomes
(Outcome-Type) and task demands (Task) on ratings of surprise for simple story
scenarios. For the Outcome-Type variable, participants saw outcomes that were
either known or less-known surprising outcomes for each scenario. For the Task
variable, participants either answered comprehension questions or provided an
explanation of the outcome. Outcome-Type reliably affected surprise judgments;
known outcomes were rated as less surprising than less-known outcomes. Task
also reliably affected surprise judgments; when people provided an explanation
it lowered surprise judgments relative to simply answering comprehension
questions. Both experiments thus provide evidence on this less-explored
explanation aspect of surprise, specifically showing that ease of explanation
is a key factor in determining the level of surprise experienced.


title: Diagonalization of the infinite q-boson system

abstract:
  We present a hierarchy of commuting operators in Fock space containing the
q-boson Hamiltonian on $\mathbb{Z}$ and show that the operators in question are
simultaneously diagonalized by Hall-Littlewood functions. As an application,
the n-particle scattering operator is computed.


title:
Applications of homological mirror symmetry to hypergeometric systems:
  duality conjectures

abstract:
  Homological mirror symmetry for crepant resolutions of Gorenstein toric
singularities leads to a pair of conjectures on certain hypergeometric systems
of PDEs. We explain these conjectures and verify them in some cases.


title:
From Higgs to pions and Back -- the Unbearable Lightness of a Composite
  Scalar Boson at 125 GeV in Purely Vectorial Theories

abstract:
  We argue that the $125 GeV$ "Higgs" particle is unlikely to arise as a
fermion- antifermion composite if the underlying dynamics is a vectorial gauge
theory. The reason is that the lightest scalar in such theories is heavier than
the lightest pseudo-scalar with the mass difference being fixed by the scale of
the theory. LHC searches suggest that the scale of any new physics, including
that of a putative new theory dynamically generating the 125 GeV "Higgs"
particle, is relatively high $\sim{(1/2TeV-1TeV)}$. Also the LHC analysis
suggests that it is {\it scalar} namely $J^P = 0^+$ rather than pseudo-scalar.
Thus it is unlikely that the "Higgs" could arise as a composite in such
theories- though it will arise in special cases when the underlying binding
gauge group is real as a fermion-fermion bound state.
  The direct considerations of the various two point functions in the large
$N_c$ limit presented below- suggest that massless pseudo-scalars, but not any
other anomalously light meson, arise as composites of massless fermions say the
massless u and $\bar{d}$ quarks in QCD. These massless pions manifest the
spontaneous breaking of the global axial symmetry in QCD with the pions being
(pseudo) Nambu Goldstone Bosons. This offers a different insight into SXSB in
QCD and most other confining non-abelian gauge vectorial gauge theory.
Specifically we consider the euclidean two point functions $F_I|x-y|$ for
asymptotic $|x-y|$ expressed as a sum over fermionic paths. We conjecture that
for the pseudo-scalar two point function - and for that case only- self
retracing paths and closely related paths make in this limit a positive,
coherent and dominant contribution, a contribution which evades the generic
asymptotic exponential fall-off and allows the lightest pseudoscalars to be
massless. The same arguments imply that the scalars are very massive.


title: Cognitive residues of similarity

abstract:
  What are the cognitive after-effects of making a similarity judgement? What,
cognitively, is left behind and what effect might these residues have on
subsequent processing? In this paper, we probe for such after-effects using a
visual search task, performed after a task in which pictures of real-world
objects were compared. So, target objects were first presented in a comparison
task (e.g., rate the similarity of this object to another) thus, presumably,
modifying some of their features before asking people to visually search for
the same object in complex scenes (with distractors and camouflaged
backgrounds). As visual search is known to be influenced by the features of
target objects, then any after-effects of the comparison task should be
revealed in subsequent visual searches. Results showed that when people
previously rated an object as being high on a scale (e.g., colour similarity or
general similarity) then visual search is inhibited (slower RTs and more
saccades in eye-tracking) relative to an object being rated as low in the same
scale. There was also some evidence that different comparison tasks (e.g.,
compare on colour or compare on general similarity) have differential effects
on visual search.


title: Particle Shape Effects on the Stress Response of Granular Packings

abstract:
  We present measurements of the stress response of packings formed from a wide
range of particle shapes. Besides spheres these include convex shapes such as
the Platonic solids, truncated tetrahedra, and triangular bipyramids, as well
as more complex, non-convex geometries such as hexapods with various arm
lengths, dolos, and tetrahedral frames. All particles were 3D-printed in hard
resin. Well-defined initial packing states were established through
preconditioning by cyclic loading under given confinement pressure. Starting
from such initial states, stress-strain relationships for axial compression
were obtained at four different confining pressures for each particle type.
While confining pressure has the largest overall effect on the mechanical
response, we find that particle shape controls the details of the stress-strain
curves and can be used to tune packing stiffness and yielding. By correlating
the experimentally measured values for the effective Young's modulus under
compression, yield stress and energy loss during cyclic loading, we identify
trends among the various shapes that allow for designing a packing's aggregate
behavior.


title: The semi-infinite q-boson system with boundary interaction

abstract:
  Upon introducing a one-parameter quadratic deformation of the q-boson algebra
and a diagonal perturbation at the end point, we arrive at a semi-infinite
q-boson system with a two-parameter boundary interaction. The eigenfunctions
are shown to be given by Macdonald's hyperoctahedral Hall-Littlewood functions
of type BC. It follows that the n-particle spectrum is bounded and absolutely
continuous and that the corresponding scattering matrix factorizes as a product
of two-particle bulk and one-particle boundary scattering matrices.


title: Restoration of Chiral Symmetry from a Boundary

abstract:
  The imposition of Dirichlet boundary conditions in lattice computations
obstructs the formation of a chiral condensate. We use chiral perturbation
theory and meson models to address the effect of a Dirichlet boundary on chiral
symmetry breaking. While pions are the longest-range modes in QCD, the
restoration of chiral symmetry due to a boundary is shown not to depend upon
the pion Compton wavelength but rather on that of the sigma meson. Power-law
finite size corrections are exposed, and require prohibitively large lattices
to overcome. We further speculate on the frustration of the chiral condensate
for the case of confinement to the surface of a sphere.


title: Higgs Inflation at NNLO after the Boson Discovery

abstract:
  We obtain the bound on the Higgs and top masses to have Higgs inflation
(where the Higgs field is non-minimally coupled to gravity) at full
next-to-next-to-leading order (NNLO). Comparing the result obtained with the
experimental values of the relevant parameters we find some tension, which we
quantify. Higgs inflation, however, is not excluded at the moment as the
measured values of the Higgs and top masses are close enough to the bound once
experimental and theoretical uncertainties are taken into account.


title: Plutonium hexaboride is a correlated topological insulator

abstract:
  We predict that plutonium hexaboride (PuB6) is a strongly correlated
topological insulator, with Pu in an intermediate valence state of Pu^2.7+ .
Within the combination of dynamical mean field theory and density functional
theory, we show that PuB6 is an insulator in the bulk, with non-trivial Z2
topological invariants. Its metallic surface states have large Fermi pocket at
X Dirac cones inside the bulk derived electronic states causing a large surface
thermal conductivity. PuB6 has also a very high melting temperature therefore
it has ideal solid state properties for a nuclear fuel material.


title:
Observation of Autler-Townes effect in a dispersively dressed
  Jaynes-Cummings system

abstract:
  Photon number splitting is observed in a transmon coupled to a
superconducting quasi-lumped-element resonator in the strong dispersive limit.
A thermal population of 5.474 GHz photons at an effective resonator temperature
of T = 120mK results in a weak n = 1 photon peak along with the n = 0 photon
peak in the qubit spectrum in the absence of a coherent drive on the resonator.
  Two-tone spectroscopy using independent coupler and probe tones reveals an
Autler-Townes splitting in the thermal n = 1 photon peak.
  The observed effect is explained accurately using the four lowest levels of
the dispersively dressed qubit-resonator system and compared to results from
numerical simulations of the steady-state master equation for the coupled
system.


title: Large values of the additive energy in R^d and Z^d

abstract:
  Combining Freiman's theorem with Balog-Szemeredi-Gowers theorem one can show
that if an additive set has large additive energy, then a large piece of the
set is contained in a generalized arithmetic progression of small rank and
size. In this paper, we prove the above statement with the optimal bound for
the rank of the progression. The proof strategy involves studying upper bounds
for additive energy of subsets of R^d and Z^d.


title:
Topology Identification of Directed Dynamical Networks via Power
  Spectral Analysis

abstract:
  We address the problem of identifying the topology of an unknown weighted,
directed network of LTI systems stimulated by wide-sense stationary noises of
unknown power spectral densities. We propose several reconstruction algorithms
based on the cross-power spectral densities of the network's response to the
input noises. Our first algorithm reconstructs the Boolean structure (i.e.,
existence and directions of links) of a directed network from a series of
dynamical responses. Moreover, we propose a second algorithm to recover the
exact structure of the network (including edge weights), as well as the power
spectral density of the input noises, when an eigenvalue-eigenvector pair of
the connectivity matrix is known (for example, Laplacian connectivity
matrices). Finally, for the particular cases of nonreciprocal networks (i.e.,
networks with no directed edges pointing in opposite directions) and undirected
networks, we propose specialized algorithms that result in a lower
computational cost.


title: Emergent gravity in graphene

abstract:
  We reconsider monolayer graphene in the presence of elastic deformations. It
is described by the tight - binding model with varying hopping parameters. We
demonstrate, that the fermionic quasiparticles propagate in the emergent 2D
Weitzenbock geometry and in the presence of the emergent U(1) gauge field. Both
emergent geometry and the gauge field are defined by the elastic deformation of
graphene.


title: Weak reflection principle for L\'evy processes

abstract:
  In this paper, we develop a new mathematical technique which allows us to
express the joint distribution of a Markov process and its running maximum (or
minimum) through the marginal distribution of the process itself. This
technique is an extension of the classical reflection principle for Brownian
motion, and it is obtained by weakening the assumptions of symmetry required
for the classical reflection principle to work. We call this method a weak
reflection principle and show that it provides solutions to many problems for
which the classical reflection principle is typically used. In addition, unlike
the classical reflection principle, the new method works for a much larger
class of stochastic processes which, in particular, do not possess any strong
symmetries. Here, we review the existing results which establish the weak
reflection principle for a large class of time-homogeneous diffusions on a real
line and then proceed to extend this method to the L\'{e}vy processes with
one-sided jumps (subject to some admissibility conditions). Finally, we
demonstrate the applications of the weak reflection principle in financial
mathematics, computational methods and inverse problems.


title:
Critical line of the $\Phi^4$ scalar field theory on a 4D cubic lattice
  in the local potential approximation

abstract:
  We establish the critical line of the one-component $\Phi^4$ (or
Landau-Ginzburg) model on a simple four dimensional cubic lattice. Our study is
performed in the framework of the non-perturbative renormalization group in the
local potential approximation with a soft infra-red regulator. The transition
is found to be of second order even in the Gaussian limit where first order
would be expected according to some recent theoretical predictions.


title: KeSeF - Kepler Self Follow-up Mission

abstract:
  The Kepler spacecraft is currently unable to hold a steady pointing and it is
slowly drifting during observations. We believe that if one has to deal with
targets that drift across the CCDs, one should at least be able to track the
targets well enough to correct for some -- if not most -- of the problems
caused by this drift. We therefore propose to observe as many stars as possible
in short cadance. We propose that at least all currently known planetary
candidate host stars will be so observed, with possibly known Kepler eclipsing
binaries, astroseismology targets, guest observer targets and new targets in
increasingly lower priority. We also outline the modifications needed to flight
software in order allow for such observations to take place, aiming to provide
ample non-photometric data that should allow post-processing to recover most of
the pre-failure photometric performance. In total, the KeSeF Mission will allow
Kepler to follow up it's own previous discoveries in a way that is not
otherwise possible. By doing so it will enable to continue pursuing nearly all
the science goals that made the original mission choose staring at a single
field of view in the first place.


title: Periods and nonvanishing of central L-values for GL(2n)

abstract:
  Let $\pi$ be a cuspidal automorphic representation of PGL($2n$) over a number
field $F$, and $\eta$ the quadratic idele class character attached to a
quadratic extension $E/F$. Guo and Jacquet conjectured a relation between the
nonvanishing of $L(1/2,\pi)L(1/2, \pi \otimes \eta)$ for $\pi$ of symplectic
type and the nonvanishing of certain GL($n,E$) periods. When $n=1$, this
specializes to a well-known result of Waldspurger. We prove this conjecture,
and related global results, under some local hypotheses using a simple relative
trace formula.
  We then apply these global results to obtain local results on distinguished
supercuspidal representations, which partially establish a conjecture of Prasad
and Takloo-Bighash.


title:
Optimal investment for all time horizons and Martin boundary of
  space-time diffusions

abstract:
  This paper is concerned with the axiomatic foundation and explicit
construction of a general class of optimality criteria that can be used for
investment problems with multiple time horizons, or when the time horizon is
not known in advance. Both the investment criterion and the optimal strategy
are characterized by the Hamilton-Jacobi-Bellman equation on a semi-infinite
time interval. In the case when this equation can be linearized, the problem
reduces to a time-reversed parabolic equation, which cannot be analyzed via the
standard methods of partial differential equations. Under the additional
uniform ellipticity condition, we make use of the available description of all
minimal solutions to such equations, along with some basic facts from potential
theory and convex analysis, to obtain an explicit integral representation of
all positive solutions. These results allow us to construct a large family of
the aforementioned optimality criteria, including some closed form examples in
relevant financial models.


title: Higgs-Boson Couplings Beyond the Standard Model

abstract:
  The implications for Higgs decays of potential new physics beyond the
Standard Model (BSM) are considered in the context of effective field theory,
assuming perturbative decoupling. Using existing data to restrict which
dimension-six operators can arise, it is shown that, given the existing
experimental constraints, only a small number of operators can affect the
decays of the Higgs: those that may be potentially-tree-generated (PTG) and
modify the Higgs-fermion couplings, or those that may be loop-generated (LG)
that modify the Higgs couplings to photon-photon, Z-photon and gluon-gluon.
Implications for specific branching ratios are given in terms of the
coefficients of various dimension six operators. In such a scenario, the ratios
Width(H -> WW*)/Width(H -> ZZ*) and Width(H -> W l nu)/Width(H -> Z l l) equal
to their standard model values to an accuracy of O(1%) or less.


title:
The Search for Neutrino-Antineutrino Mixing from Lorentz Invariance
  Violation using Neutrino Interactions in MINOS

abstract:
  We searched for a sidereal modulation in the rate of neutrinos observed by
the MINOS far detector. The detection of these signals could be a signature of
neutrino-antineutrino mixing due to Lorentz and CPT violation as described by
the Standard-Model Extension framework. We found no evidence for these sidereal
signals and we placed limits on the coefficients in this theory describing the
effect.


title:
The Ages of 55 Globular Clusters as Determined Using an Improved delta
  V_TO^HB Method Along with Color-Magnitude Diagram Constraints, and Their
  Implications for Broader Issues

abstract:
  Ages have been derived for 55 globular clusters (GCs) from overlays of
isochrones onto the turnoff photometry, assuming distances based on fits of
zero-age horizontal branch (ZAHB) models to the lower bound of the observed
distributions of HB stars. The error bar arising just from the "fitting" of
ZAHBs and isochrones is ~ +/- 0.25 Gyr, while that associated with distance and
chemical abundance uncertainties is ~ +/- 1.5-2 Gyr. Ages vary from mean values
of ~12.5 Gyr at [Fe/H] < -1.7 to ~11 Gyr at [Fe/H] > -1.0. At intermediate
metallicities, the age-metallicity relation (AMR) appears to be bifurcated: one
branch apparently contains clusters with disk-like kinematics, whereas the
other branch is populated by clusters with halo-type orbits. There is no
apparent dependence of age on Galactocentric distance (R_G) nor is there a
clear correlation of HB type with age. Subtle variations in the subgiant branch
(SGB) slopes of [Fe/H] < -1.5 GCs are tentatively attributed to helium
abundance differences. Curiously, GCs with steep "M13-like" SGBs tend to be
massive systems, located at small R_G, that show the strongest evidence for
multiple stellar populations. The others are typically low-mass systems that,
at the present time, should not be able to retain the matter lost by
mass-losing stars. The apparent separation of the two groups in terms of their
present-day gas retention properties is difficult to understand if all GCs were
initial ~20 times their current masses. The lowest mass systems may have never
been able to retain enough gas to produce a significant population of
second-generation stars; in this case, the observed light element abundance
variations were presumably present in the gas out of which the observed cluster
stars formed.


title:
Carbyne from first principles: Chain of C atoms, a nanorod or a
  nanorope?

abstract:
  We report an extensive study of the properties of carbyne using
first-principles calculations. We investigate carbyne's mechanical response to
tension, bending, and torsion deformations. Under tension, carbyne is about
twice as stiff as the stiffest known materials and has an unrivaled specific
strength of up to 7.5*10^7 Nm/kg, requiring a force of ~10 nN to break a single
atomic chain. Carbyne has a fairly large room-temperature persistence length of
about 14 nm. Surprisingly, the torsional stiffness of carbyne can be zero but
can be 'switched on' by appropriate functional groups at the ends. Further,
under appropriate termination, carbyne can be switched into a
magnetic-semiconductor state by mechanical twisting. We reconstruct the
equivalent continuum-elasticity representation, providing the full set of
elastic moduli for carbyne, showing its extreme mechanical performance (e.g. a
nominal Young's modulus of 32.7 TPa with an effective mechanical thickness of
0.772 A). We also find an interesting coupling between strain and band gap of
carbyne, which is strongly increased under tension, from 3.2 to 4.4 eV under a
10% strain. Finally, we study the performance of carbyne as a nanoscale
electrical cable, and estimate its chemical stability against self-aggregation,
finding an activation barrier of 0.6 eV for the carbyne-carbyne cross-linking
reaction and an equilibrium cross-link density for two parallel carbyne chains
of 1 cross-link per 17 C atoms (2.2 nm).


title:
On sharp constants in one-dimensional embedding theorems of arbitrary
  order

abstract:
  We discuss the problem where the extremal function in embedding theorem of
some (generally speaking, non-integer) order is the constant function. We
obtain the necessary and sufficient conditions of this.


title: Communication Practices in a Distributed Scrum Project

abstract:
  While global software development (GSD) projects face cultural and time
differences, the biggest challenge is communication. We studied a distributed
student project with an industrial customer. The project lasted 3 months,
involved 25 participants, and was distributed between the University of
Victoria, Canada and Aalto University, Finland. We analyzed email
communication, version control system (VCS) data, and surveys on satisfaction.
Our aim was to find out whether reflecting on communication affected it, if
standups influenced when developers committed to the VCS repository, and if
leaders emerged in the three distributed Scrum teams. Initially students sent
on average 21 emails per day. With the reduction to 16 emails, satisfaction
with communication increased. By comparing Scrum standup times and VCS activity
we found that the live communication of standups activated people to work on
the project. Out of the three teams, one had an emergent communication
facilitator.


title: On the rank one abelian Gross-Stark conjecture

abstract:
  Let $F$ be a totally real number field, $p$ a rational prime, and $\chi$ a
finite order totally odd abelian character of Gal$(\bar{F}/F)$ such that
$\chi(\mathfrak{p})=1$ for some $\mathfrak{p}|p$. Motivated by a conjecture of
Stark, Gross conjectured a relation between the derivative of the $p$-adic
$L$-function associated to $\chi$ at its exceptional zero and the
$\mathfrak{p}$-adic logarithm of a $p$-unit in the $\chi$ component of
$F_\chi^\times$. In a recent work, Dasgupta, Darmon, and Pollack have proven
this conjecture assuming two conditions: that Leopoldt's conjecture holds for
$F$ and $p$, and that if there is only one prime of $F$ lying above $p$, a
certain relation holds between the $\mathscr{L}$-invariants of $\chi$ and
$\chi^{-1}$. The main result of this paper removes both of these conditions,
thus giving an unconditional proof of the conjecture.


title:
Comment on `Comment on `Some novel delta-function identities' by Charles
  P Frahm (Am. J. Phys 51 826--9 (1983))' by J. Franklin (Am. J. Phys 78
  1225--26 (2010))

abstract:
  We prove the formula for the second order "thick" distributional derivative
of 1/r in 3 dimensional Euclidean space. This formula generalizes the well
known Frahm formulas for the distributional derivatives of 1/r.


title: Algebraic topology of $G_2$ manifolds

abstract:
  In this paper we give a survey of various results about the topology of
oriented Grassmannian bundles related to the exceptional Lie group G_2. Some of
these results are new. We give self-contained proofs here. One often encounters
these spaces when studying submanifolds of manifolds with calibrated
geometries. For the sake of completeness we decided to collect them here in a
self-contained way to be easily accessible for future usage in calibrated
geometry. As an application we deduce existence of certain special 3 and 4
dimensional submanifolds of G_2 manifolds with special properties, which appear
in the first named author's work with S. Salur about G_2 dualities.


title:
Error Performance Analysis of DF and AF Multi-way Relay Networks with
  BPSK Modulation

abstract:
  In this paper, we analyze the error performance of decode and forward (DF)
and amplify and forward (AF) multi-way relay networks (MWRN). We consider a
MWRN with pair-wise data exchange protocol using binary phase shift keying
(BPSK) modulation in both additive white Gaussian noise (AWGN) and Rayleigh
fading channels. We quantify the possible error events in an $L$-user DF or AF
MWRN and derive accurate asymptotic bounds on the probability for the general
case that a user incorrectly decodes the messages of exactly $k$
($k\in[1,L-1]$) users. We show that at high signal-to-noise ratio (SNR), the
higher order error events ($k\geq 3$) are less probable in AF MWRN, but all
error events are equally probable in a DF MWRN. We derive the average BER of a
user in a DF or AF MWRN in both AWGN and Rayleigh fading channels under high
SNR conditions. Simulation results validate the correctness of the derived
expressions. Our results show that at medium to high SNR, DF MWRN provides
better error performance than AF MWRN in AWGN channels even with a large number
of users (for example, L=100). Whereas, AF MWRN outperforms DF MWRN in Rayleigh
fading channels even for much smaller number of users (for example, $L > 10$).


title:
Measurement of the electronic thermal conductance channels and heat
  capacity of graphene at low temperature

abstract:
  The ability to transport energy is a fundamental property of the
two-dimensional Dirac fermions in graphene. Electronic thermal transport in
this system is relatively unexplored and is expected to show unique fundamental
properties and to play an important role in future applications of graphene,
including opto-electronics, plasmonics, and ultra-sensitive bolometry. Here we
present measurements of bipolar, electron-diffusion and electron-phonon thermal
conductances, and infer the electronic specific heat, with a minimum value of
10 $k_{\rm{B}}$ ($10^{-22}$ JK$^{-1}$) per square micron. We test the validity
of the Wiedemann-Franz law and find the Lorenz number equals
$1.32\times(\pi^2/3)(k_{\rm{B}}/e)^2$. The electron-phonon thermal conductance
has a temperature power law $T^2$ at high doping levels, and the coupling
parameter is consistent with recent theory, indicating its enhancement by
impurity scattering. We demonstrate control of the thermal conductance by
electrical gating and by suppressing the diffusion channel using
superconducting electrodes, which sets the stage for future graphene-based
single microwave photon detection.


title: Decoherence via coupling to a finite quantum heat bath

abstract:
  Decoherence of a quantum state coupled to an exterior environment is at the
foundation of our understanding of the emergence of classical behavior from the
quantum world, but how does it emerge in a finite closed quantum system? Here
this is studied by modeling an isolated quantum system of a handful of
ultracold atoms confined to a double well potential and coupled to a single
atom of a different type. The ultracold atoms thermalize and serve as an
environmental bath for the single atom. We observe accelerated decoherence of
the single atom when ultracold atoms have thermalized. This is explained by the
emergence of chaotic eigenstates in the thermalized system.


title: Arrival statistics and exploration properties of mortal walkers

abstract:
  We study some of the salient features of the arrival statistics and
exploration properties of mortal random walkers, that is, walkers that may die
as they move, or as they wait to move. Such evanescence or death events have
profound consequences for quantities such as the number of distinct sites
visited which are relevant for the computation of encounter-controlled rates in
chemical kinetics. We exploit the observation that well-known methods developed
decades ago for immortal walkers are widely applicable to mortal walkers. The
particular cases of exponential and power-law evanescence are considered in
detail. Finally, we discuss the relevance of our results to the target problem
with mortal traps and a particular application thereof, namely, the defect
diffusion model. Evanescence of defects is postulated as a possible
complementary contribution or perhaps even an alternative to anomalous
diffusion to explain observed stretched exponential relaxation behavior.


title: Growth and integrability of Fourier transforms on Euclidean space

abstract:
  A fundamental theme in classical Fourier analysis relates smoothness
properties of functions to the growth and/or integrability of their Fourier
transform. By using a suitable class of $L^{p}-$multipliers, a rather general
inequality controlling the size of Fourier transforms for large and small
argument is proved. As consequences, quantitative Riemann-Lebesgue estimates
are obtained and an integrability result for the Fourier transform is developed
extending ideas used by Titchmarsh in the one dimensional setting.


title: Maximum matchings in regular graphs

abstract:
  It was conjectured by Mkrtchyan, Petrosyan, and Vardanyan that every graph
$G$ with $\Delta(G)-\delta(G) \le 1$ has a maximum matching $M$ such that any
two $M$-unsaturated vertices do not share a neighbor. In this note, we confirm
the conjecture for all $k$-regular simple graphs and also $k$-regular
multigraphs with $k\le 4$.


title:
Applications of vertex algebra covering procedures to Chevalley groups
  and modular moonshine

abstract:
  A vertex operator algebra of lattice type ADE has a standard integral form
which extends a Chevalley basis for its degree 1 Lie algebra. This integral
form may be used to define a vertex algebra over a commutative ring $R$ and to
get a Chevalley group over $R$ of the same type, acting as automorphisms of
this vertex algebra. We define vertex algebras of types BCFG over a commutative
ring and certain reduced VAs, then get analogous results about automorphism
groups. In characteristics 2 and 3, there are exceptionally large automorphism
groups. A covering algebra idea of Frohardt and Griess for Lie algebras is
applied to the vertex algebra situation.
  We use integral form and covering procedures for vertex algebras to complete
the modular moonshine program of Borcherds and Ryba for proving an embedding of
the sporadic group $F_3$ in $E_8(3)$.


title: Khovanov-Kauffman Homology for embedded Graphs

abstract:
  A discussion given to the question of extending Khovanov homology from links
to embedded graphs, by using the Kauffman topological invariant of embedded
graphs by associating family of links and knots to a such graph by using some
local replacements at each vertex in the graph.
  This new concept of Khovanov-Kauffman homology of an embedded graph
constructed to be the sum of the Khovanov homologies of all the links and knots
associated to this graph.