title: The CMSSM and NUHM1 after LHC Run 1

abstract:
  We analyze the impact of data from the full Run 1 of the LHC at 7 and 8 TeV
on the CMSSM with mu > 0 and < 0 and the NUHM1 with mu > 0, incorporating the
constraints imposed by other experiments such as precision electroweak
measurements, flavour measurements, the cosmological density of cold dark
matter and the direct search for the scattering of dark matter particles in the
LUX experiment. We use the following results from the LHC experiments: ATLAS
searches for events with MET accompanied by jets with the full 7 and 8 TeV
data, the ATLAS and CMS measurements of the mass of the Higgs boson, the CMS
searches for heavy neutral Higgs bosons and a combination of the LHCb and CMS
measurements of B_s to mu+mu- and B_d to mu+mu-. Our results are based on
samplings of the parameter spaces of the CMSSM for both mu>0 and mu<0 and of
the NUHM1 for mu > 0 with 6.8 x 10^6, 6.2 x 10^6 and 1.6 x 10^7 points,
respectively, obtained using the MultiNest tool. The impact of the Higgs mass
constraint is assessed using FeynHiggs 2.10.0, which provides an improved
prediction for the masses of the MSSM Higgs bosons in the region of heavy
squark masses. It yields in general larger values of M_h than previous versions
of FeynHiggs, reducing the pressure on the CMSSM and NUHM1. We find that the
global chi^2 functions for the supersymmetric models vary slowly over most of
the parameter spaces allowed by the Higgs mass and the MET searches, with
best-fit values that are comparable to the chi^2/dof for the best Standard
Model fit. We provide 95% CL lower limits on the masses of various sparticles
and assess the prospects for observing them during Run 2 of the LHC.


title:
Quantum phase transition in the chirality of the (2+1)-dimensional Dirac
  oscillator

abstract:
  We study the (2+1)-dimensional Dirac oscillator in the presence of an
external uniform magnetic field ($B$). We show how the change of the strength
of $B$ leads to the existence of a quantum phase transition in the chirality of
the system. A critical value of the strength of the external magnetic field
($B_c$) can be naturally defined in terms of physical parameters of the system.
While for $B=B_c$ the fermion can be considered as a free particle without
defined chirality, for $B<B_c$ ($B>B_c$) the chirality is left (right) and
there exist a net potential acting on the fermion. For the three regimes
defined in the quantum phase transition of chirality, we observe that the
energy spectra for each regime is drastically different. Then, we consider the
$z$-component of the orbital angular momentum as an order parameter that
characterizes the quantum phase transition.


title:
Ultra-Sensitive Chip-Based Photonic Temperature Sensor Using Ring
  Resonator Structures

abstract:
  Resistance thermometry provides a time-tested method for taking temperature
measurements. However, fundamental limits to resistance-based approaches has
produced considerable interest in developing photonic temperature sensors to
leverage advances in frequency metrology and to achieve greater mechanical and
environmental stability. Here we show that silicon-based optical ring resonator
devices can resolve temperature differences of 1 mK using the traditional
wavelength scanning methodology. An even lower noise floor of 80 microkelvin
for measuring temperature difference is achieved in the side-of-fringe,
constant power mode measurement.


title:
Dressing with Control: using integrability to generate desired solutions
  to Einstein's equations

abstract:
  Motivated by integrability of the sine-Gordon equation, we investigate a
technique for constructing desired solutions to Einstein's equations by
combining a dressing technique with a control-theory approach. After reviewing
classical integrability, we recall two well-known Killing field reductions of
Einstein's equations, unify them using a harmonic map formulation, and state
two results on the integrability of the equations and solvability of the
dressing system. The resulting algorithm is then combined with an asymptotic
analysis to produce constraints on the degrees of freedom arising in the
solution-generation mechanism. The approach is carried out explicitly for the
Einstein vacuum equations. Applications of the technique to other geometric
field theories are also discussed.


title: McKay Centralizer Algebras

abstract:
  For a finite subgroup $G$ of the special unitary group $SU_2$, we study the
centralizer algebra $Z_k(G) = End_G(V^{\otimes k})$ of $G$ acting on the
$k$-fold tensor product of its defining representation $V= \mathbb{C}^2$. These
subgroups are in bijection with the simply-laced affine Dynkin diagrams. The
McKay correspondence relates the representation theory of these groups to the
associated Dynkin diagram, and we use this connection to show that the
structure and representation theory of $Z_k(G)$ as a semisimple algebra is
controlled by the combinatorics of the corresponding Dynkin diagram.


title: Muckenhoupt-Wheeden conjectures in higher dimensions

abstract:
  In recent work by Reguera and Thiele and by Reguera and Scurry, two
conjectures about joint weighted estimates for Calder\'on-Zygmund operators and
the Hardy-Littlewood maximal function have been refuted in the one-dimensional
case. One of the key ingredients for these results is the construction of
weights for which the action of the Hilbert transform is substantially bigger
than that of the maximal function. In this work, we show that a similar
construction is possible for classical Calder\'on-Zygmund operators in higher
dimensions. This allows us to fully disprove the conjectures.


title:
Cosmological Perturbation Theory as a Tool for Estimating Box-Scale
  Effects in N-body Simulations

abstract:
  In performing cosmological N-body simulations, it is widely appreciated that
the growth of structure on the largest scales within a simulation box will be
inhibited by the finite size of the simulation volume. Following ideas set
forth in Seto (1999), this paper shows that standard (a.k.a. 1-loop)
cosmological perturbation theory (SPT) can be used to predict, in an
approximate way, the deleterious effect of the box scale on the power spectrum
of density fluctuations in simulation volumes. Alternatively, this approach can
be used to quickly estimate post facto the effect of the box scale on power
spectrum results from existing simulations. In this way SPT can help determine
whether larger box sizes or other more-sophisticated methods are needed to
achieve a particular level of precision for a given application (e.g.
simulations to measure the non-linear evolution of baryon acoustic
oscillations). I focus on SPT in this note and show that its predictions differ
only by about a factor of two or less from the measured suppression inferred
from both powerlaw and $\Lambda$CDM $N$-body simulations. It should be possible
to improve the accuracy of these predictions through using more-sophisticated
perturbation theory models. An appendix compares power spectrum measurements
from the powerlaw simulations at outputs where box-scale effects are minimal to
perturbation theory models and previously-published fitting functions. These
power spectrum measurements are included with this paper to aid efforts to
develop new perturbation theory models.


title: Cyclostationary Spectrum Sensing in Cognitive Radios Using FRESH Filters

abstract:
  This paper deals with spectrum sensing in Cognitive Radios to enable
unlicensed secondary users to opportunistically access a licensed band. The
ability to detect the presence of a primary user at a low signal to noise ratio
(SNR) is a challenging prerequisite to spectrum sensing and earlier proposed
techniques like energy detection and cyclostationary detection have only been
partially successful. This paper proposes the use of FRESH (FREquency SHift)
filters [1] to enable spectrum sensing at low SNR by optimally estimating a
cyclostationary signal using its spectral coherence properties. We establish
the mean square error convergence of the adaptive FRESH filter through
simulation. Subsequently, we formulate a cyclostationarity based binary
hypothesis test on the filtered signal and observe the resultant detection
performance. Simulation results show that the proposed approach performs better
than energy detection and cyclostationary detection techniques for spectrum
sensing.


title: On the Challenges of Physical Implementations of RBMs

abstract:
  Restricted Boltzmann machines (RBMs) are powerful machine learning models,
but learning and some kinds of inference in the model require sampling-based
approximations, which, in classical digital computers, are implemented using
expensive MCMC. Physical computation offers the opportunity to reduce the cost
of sampling by building physical systems whose natural dynamics correspond to
drawing samples from the desired RBM distribution. Such a system avoids the
burn-in and mixing cost of a Markov chain. However, hardware implementations of
this variety usually entail limitations such as low-precision and limited range
of the parameters and restrictions on the size and topology of the RBM. We
conduct software simulations to determine how harmful each of these
restrictions is. Our simulations are designed to reproduce aspects of the
D-Wave quantum computer, but the issues we investigate arise in most forms of
physical computation.


title: Temporal percolation in activity driven networks

abstract:
  We study the temporal percolation properties of temporal networks by taking
as a representative example the recently proposed activity driven network model
[N. Perra et al., Sci. Rep. 2, 469 (2012)]. Building upon an analytical
framework based on a mapping to hidden variables networks, we provide
expressions for the percolation time marking the onset of a giant connected
component in the integrated network. In particular, we consider both the
generating function formalism, valid for degree uncorrelated networks, and the
general case of networks with degree correlations. We discuss the different
limits of the two approach, indicating the parameter regions where the
correlated threshold collapses onto the uncorrelated case. Our analytical
prediction are confirmed by numerical simulations of the model. The temporal
percolation concept can be fruitfully applied to study epidemic spreading on
temporal networks. We show in particular how the susceptible-infected- removed
model on an activity driven network can be mapped to the percolation problem up
to a time given by the spreading rate of the epidemic process. This mapping
allows to obtain addition information on this process, not available for
previous approaches.


title: The Six Circles Theorem revisited

abstract:
  The Six Circles Theorem of C. Evelyn, G. Money-Coutts, and J. Tyrrell
concerns chains of circles inscribed into a triangle: the first circle is
inscribed in the first angle, the second circle is inscribed in the second
angle and tangent to the first circle, the third circle is inscribed in the
third angle and tangent to the second circle, and so on, cyclically. The
theorem asserts that if all the circles touch the sides of the triangle, and
not their extensions, then the chain is 6-periodic. We show that, in general,
the chain is eventually 6-periodic but may have an arbitrarily long pre-period.


title: Probing the models: Abundances for high-mass stars in binaries

abstract:
  The complexity of composite spectra of close binary star system makes study
of the spectra of their component stars extremely difficult. For this reason
there exists very little information on the photospheric chemical composition
of stars in close binaries, despite its importance for informing our
understanding of the evolutionary processes of stars. In a long-term
observational project we aim to fill this gap with systematic abundance studies
for the variety of binary systems. The core of our analysis is the spectral
disentangling technique, which allows isolation of the individual component
star spectra from the time-series of observed spectra.
  We present new results for high-mass stars in close binaries. So far, we have
measured detailed abundances for 22 stars in a dozen detached binary systems.
The parameter space for the stars in our sample comprises masses in the range
8--22 M_sun, surface gravities of 3.1--4.2 (c.g.s.) and projected rotational
velocities of 30--240 km/s. Whilst recent evolutionary models for rotating
single stars predict changes in photospheric abundances even during the main
sequence lifetime, no star in our sample shows signs of these predicted
changes. It is clear that other effects prevail in the chemical evolution of
components in binary stars even at the beginning of their evolution.


title:
Coverage versus Supply Cost in Facility Location: Physics of Frustrated
  Spin Systems

abstract:
  A comprehensive coverage is crucial for communication, supply and
transportation networks, yet it is limited by the requirement of extensive
infrastructure and heavy energy consumption. Here we draw an analogy between
spins in antiferromagnet and outlets in supply networks, and apply techniques
from the studies of disordered systems to elucidate the effects of balancing
the coverage and supply costs on the network behavior. A readily applicable,
coverage optimization algorithm is derived. Simulation results show that
magnetized and antiferromagnetic domains emerge and coexist to balance the need
for coverage and energy saving. The scaling of parameters with system size
agrees with the continuum approximation in two dimensions and the tree
approximation in random graphs. Due to frustration caused by the competition
between coverage and supply cost, a transition between easy and hard
computation regimes is observed. We further suggest a local expansion approach
to greatly simplify the message updates which shed light on simplifications in
other problems.


title:
Cryptographic security of the quantum key distribution from the triangle
  inequality

abstract:
  We show that the Csiszar-Korner sufficient condition for secure cryptographic
key generation with the help of quantum theory can be easily derived using the
triangle inequality for an information-theoretic distance.


title:
Prediction of the $D_s^*$ width from a calculation of its radiative
  decay in full lattice QCD

abstract:
  We determine the rate for $D_s^* \rightarrow D_s \gamma$ for the first time
from lattice QCD and include the full effect of $u$, $d$ and $s$ sea quarks.
The valence quarks are implemented using the Highly Improved Staggered Quark
(HISQ) formalism and we normalise the vector current nonperturbatively. We
obtain $M(D_s^*)-M(D_s)$ of 148(4) MeV, in good agreement with experiment. The
value of the decay constant of the $D_s^*$ we find to be 274(6) MeV, so that
$f_{D_s^*}/f_{D_s} = 1.10(2)$. For the radiative decay we find $\Gamma(D_s^*
\rightarrow D_s \gamma)$ = 0.066(26) keV. Given the experimental branching
fraction for this decay we predict a total width for the $D_s^*$ of 0.070(28)
keV, making this the longest lived charged vector meson.


title:
Study of the Kelvin-Helmholtz instability through simulation with the
  code Athena

abstract:
  Kelvin-Helmholtz instabilities are common in astrophysical systems, ranging
from jet black holes up to protoplanetary accretion disk. An astrophysical
object with strong characteristics of the Kelvin-Helmholtz instability is
Caraguejo Nebula, in which the material expansion was caused by the explosion
of a supernova about 1000 years ago. This instability occurs at the boundary
between two fluids of different densities when one of the fluids accelerated
with respect to the other. In order to study this instability, we performed a
simulation with the code ATHENA Eulerian mesh. For this simulation, we consider
a square domain with periodic boundaries on the sides, and reflecting on the
boundary of the top and bottom. The upper box is filled with a gas density
{\rho}=1.0, pressure P1 = 1.0, adiabatic index {\gamma}=5/3, and velocity
u1=0.03 in the x direction (to the right). The lower portion has a density
{\rho}=2.0, the same pressure, velocity, and adiabatic index, only in the
opposite direction to the left. Speed is defined as a sinusoidal function,
which creates the initial disturbance. As a result, we observe the principle of
instability and the formation of vortices, with well-defined ridges. The
distinctness of the boundary between the material of high and low density is
well preserved due to the relatively low diffusion algorithm. We also note that
the simulation evolving vortices formed from the turmoil merge.


title: Characteristic integrals in 3D and linear degeneracy

abstract:
  Conservation laws vanishing along characteristic directions of a given system
of PDEs are known as characteristic conservation laws, or characteristic
integrals. In 2D, they play an important role in the theory of
Darboux-integrable equations. In this paper we discuss characteristic integrals
in 3D and demonstrate that, for a class of second-order linearly degenerate
dispersionless integrable PDEs, the corresponding characteristic integrals are
parametrised by points on the Veronese variety.


title: On the LHCb anomaly in B -> K* l+ l-

abstract:
  The latest LHCb angular analysis of the rare decay B -> K* mu+ mu- shows some
discrepancies from the SM up to the 3.7 sigma level. There is a consistent new
physics explanation of these anomalies, while it is also reasonable that these
anomalies are just statistical fluctuations and/or a direct consequence of
underestimated hadronic uncertainties. We briefly discuss possible cross-checks
of the various hypotheses with an analysis of the inclusive B -> Xs l+ l- based
on the data collected by the B factories Babar and Belle and also based on
future opportunities at SuperBelle. We also present a global analysis of the
latest LHCb data under the hypothesis of Minimal Flavour Violation. The latter
is an important benchmark scenario for new physics models. Any measurements
beyond the MFV bounds and relations unambiguously indicate the existence of new
flavour structures next to the Yukawa couplings of the Standard Model. However,
if new physics is responsible for these discrepancies, we show it is compatible
with the MFV hypothesis, so no new flavour structures are needed. Moreover, we
analyse the impact of the correlations between the observables based on a Monte
Carlo study.


title: Extremely Slow Spin Relaxation in a Spin-Unpolarized Quantum Hall System

abstract:
  Cyclotron spin-flip excitation in a nu=2 quantum Hall system, being separated
from the ground state by a slightly smaller gap than the cyclotron energy and
from upper magnetoplasma excitation by the Coulomb gap [S. Dickmann and I.V.
Kukushkin, Phys. Rev. B 71, 241310(R) (2005) ; L.V. Kulik, I.V. Kukushkin, S.
Dickmann, V.E. Kirpichev, A.B. Vankov, A.L. Parakhonsky, J.H. Smet, K. von
Klitzing, and W. Wegscheider, Phys. Rev. B 72, 073304 (2005)] cannot relax in a
purely electronic way except only with the emission of a shortwave acoustic
phonon (k~3*10^7/cm). As a result, relaxation in a modern wide-thickness
quantum well occurs very slowly. We calculate the characteristic relaxation
time to be ~1s. Extremely slow relaxation should allow the production of a
considerable density of zero-momenta cyclotron spin-flip excitations in a very
small phase volume, thus forming a highly coherent ensemble - the Bose-Einstein
condensate. The condensate state can be controlled by short optical pulses (<1
mcs), switching it on and off.


title: c-Regular cyclically ordered groups

abstract:
  We define and we characterize regular and c-regular cyclically ordered
abelian groups. We prove that every dense c-regular cyclically ordered abelian
group is elementarily equivalent to some cyclically ordered group of unimodular
complex numbers, that every discrete c-regular cyclically ordered abelian group
is elementarily equivalent to some ultraproduct of finite cyclic groups, and
that the discrete regular non-c-regular cyclically ordered abelian groups are
elementarily equivalent to the linearly cyclically ordered group of integers.


title: Pointwise recurrence for commuting measure preserving transformations

abstract:
  Let $(X,\mathcal{A}, \mu)$ be a probability measure space and let $T_i,$
$1\leq i\leq H,$ be commuting invertible measure preserving transformations on
this measure space. We prove the following pointwise results;
  The averages
  $$\frac{1}{N}\sum_{n=1}^N f_1(T_1^nx)f_2(T_2^nx)\cdots f_H(T_H^nx)$$ converge
a.e. for every function $f_i \in L^{\infty}(\mu)$ .\\ As a consequence if $T_i
= T^i$ for $1\leq i \leq H$ where $T$ is an invertible measure preserving
transformation on $(X, \mathcal{A}, \mu)$ then the averages
  $$\frac{1}{N}\sum_{n=1}^N f_1(T^nx)f_2(T^{2n}x)...f_H(T^{Hn}x)$$ converge
a.e.
  This solves a long open question on the pointwise convergence of
nonconventional ergodic averages. For $H=2$ it provides another proof of J.
Bourgain's a.e. double recurrence theorem.


title: Systematic and multifactor risk models revisited

abstract:
  Systematic and multifactor risk models are revisited via methods which were
already successfully developed in signal processing and in automatic control.
The results, which bypass the usual criticisms on those risk modeling, are
illustrated by several successful computer experiments.


title: CP Asymmetry Measurements in D Decays from Belle

abstract:
  We present measurements of CP asymmetries in D decays performed by the Belle
experiment running at the KEKB asymmetric-energy e+e- collider.


title:
Are Superluminous Supernovae Powered By Collision Or By Millisecond
  Magnetars?

abstract:
  Using our previously derived simple analytic expression for the bolometric
light curves of supernovae, we demonstrate that the collision of the fast
debris of ordinary supernova explosions with relatively slow-moving shells from
pre-supernova eruptions can produce the observed bolometric light curves of
superluminous supernovae (SLSNe) of all types. These include both, those which
can be explained as powered by spinning-down millisecond magnetars and those
which cannot. That and the observed close similarity between the bolometric
light-curves of SLSNe and ordinary interacting SNe suggest that SLSNe are
powered mainly by collisions with relatively slow moving circumstellar shells
from pre-supernova eruptions rather than by the spin-down of millisecond
magnetars born in core collapse supernova explosions.


title:
Double-hybrid density-functional theory with meta-generalized-gradient
  approximations

abstract:
  We extend the previously proposed one-parameter double-hybrid
density-functional theory [K. Sharkas, J. Toulouse, and A. Savin, J. Chem.
Phys. 134, 064113 (2011)] to meta-generalized-gradient-approximation (meta-GGA)
exchange-correlation density functionals. We construct several variants of
one-parameter double-hybrid approximations using the
Tao-Perdew-Staroverov-Scuseria (TPSS) meta-GGA functional and test them on test
sets of atomization energies and reaction barrier heights. The most accurate
variant uses the uniform coordinate scaling of the density and of the kinetic
energy density in the correlation functional, and improves over both standard
Kohn-Sham TPSS and second-order Moller-Plesset calculations.


title: Analysis of nuclear activity of ten polar ring galaxies

abstract:
  The accumulation of mass from the interaction process that forms the polar
ring galaxies is a factor that favors the conditions necessary to trigger
nonthermal nuclear activities.. This fact encouraged the chemical analysis of
ten polar ring galaxies. In order to verify the presence of an active nucleus
in these galaxias, we built diagnostic diagrams using lines H{\beta}, [OIII],
[HI], H{\alpha}, [NII], and [SII] and classified the type of nuclear activity.
For galaxies that do not show shock, the parameters N2 and O3N2 were also
determined. From this sample, we identified seven galaxies with an active
nucleus and three that behave as HII regions. One galaxy with an active nucleus
was classified as Seyfert. Although our data do not provide a statistically
significant sample, we can speculate that polar ring galaxies are a setting
conducive to trigger non-thermal nuclear activities.


title: Integration by parts and representation of information functionals

abstract:
  We introduce a new formalism for computing expectations of functionals of
arbitrary random vectors, by using generalised integration by parts formulae.
In doing so we extend recent representation formulae for the score function
introduced in Nourdin, Peccati and Swan (JFA, to appear) and also provide a new
proof of a central identity first discovered in Guo, Shamai, and Verd{\'u}
(IEEE Trans. Information Theory, 2005). We derive a representation for the
standardized Fisher information of sums of i.i.d. random vectors which use our
identities to provide rates of convergence in information theoretic central
limit theorems (both in Fisher information distance and in relative entropy).


title:
Numerical solution of saddle point problems by block {Gram--Schmidt}
  orthogonalization

abstract:
  Saddle point problems arise in many important practical applications. In this
paper we propose and analyze some algorithms for solving symmetric saddle point
problems which are based upon the block Gram-Schmidt method. In particular, we
prove that the algorithm BCGS2 (Reorthogonalized Block Classical Gram-Schmidt)
using Householder Q-R decomposition implemented in floating point arithmetic is
backward stable, under a mild assumption on the matrix $M$. This means that the
computed vector $\tilde z$ is the exact solution to a slightly perturbed linear
system of equations $Mz = f$.


title: Aspects of fine-tuning of the Higgs mass within finite field theories

abstract:
  We reanalyze the perturbative radiative corrections to the Higgs mass within
the Standard Model in the light of the Taylor-Lagrange renormalization scheme.
This scheme naturally leads to completely finite corrections, depending on an
arbitrary scale. The formulation avoids very large individual corrections to
the Higgs mass. This illustrates the fact that the so-called fine-tuning
problem in the Standard Model is just an artifact of the regularization scheme.
It should therefore not lead to any physical interpretation in terms of the
energy scale at which new physics should show up, nor in terms of a new
symmetry. We analyze the intrinsic physical scales relevant for the description
of these radiative corrections.


title:
Self-assembly of Brownian motor by reduction of its effective
  temperature

abstract:
  Emergence, optimization and stability of a motor-like motion in a fluctuating
environment are analyzed. The emergence of motion is shown to be a general
phenomenon. A motor converges to the state with the minimum of effective
temperature and with the corresponding minimum in the rate of conformation
changes similarly as some stochastic processes converge to the states with
minimum diffusion activity. This mechanism is important to bacterial foraging
(chemotaxis). This work, therefore, raises an analogy between chemotaxis and
the emergence of living-like systems. The implications include the deviation of
stable natural or artificial machines from the minimum entropy production
principle, with a novel self-assembly mechanism for the emergence of the first
molecular motors and for mass fabrication of the future nanodevices.


title:
Dichotomies properties on computational complexity of S-packing coloring
  problems

abstract:
  This work establishes the complexity class of several instances of the
S-packing coloring problem: for a graph G, a positive integer k and a non
decreasing list of integers S = (s\_1 , ..., s\_k ), G is S-colorable, if its
vertices can be partitioned into sets S\_i , i = 1,... , k, where each S\_i
being a s\_i -packing (a set of vertices at pairwise distance greater than
s\_i). For a list of three integers, a dichotomy between NP-complete problems
and polynomial time solvable problems is determined for subcubic graphs.
Moreover, for an unfixed size of list, the complexity of the S-packing coloring
problem is determined for several instances of the problem. These properties
are used in order to prove a dichotomy between NP-complete problems and
polynomial time solvable problems for lists of at most four integers.


title: The Dark Z' Portal: Direct, Indirect and Collider Searches

abstract:
  We perform a detailed study of the dark Z' portal using a generic
parametrization of the Z'-quarks couplings, both for light (8-15)GeV and heavy
(130-1000)GeV dark matter scenarios. We present a comprehensive study of the
collider phenomenology including jet clustering, hadronization, and detector
artifacts, which allows us to derive accurate bounds from the search for new
resonances in dijet events and from mono-jet events in the LHC 7TeV, LHC 8TeV,
and Tevatron 1.96 TeV data. We also compute the dark matter relic abundance,
the relevant scattering cross sections and pair-annihilation spectrum, and
compare our results with the current PLANCK, Fermi-LAT and XENON100/LUX bounds.
Lastly, we highlight the importance of complementary searches for dark matter,
and outline the excluded versus still viable parameter space regions of the
dark Z' portal.


title: Comparing the Dynamics of Skyrmions and Superconducting Vortices

abstract:
  Vortices in type-II superconductors have attracted enormous attention as
ideal systems in which to study nonequilibrium collective phenomena, since the
self-ordering of the vortices competes with quenched disorder and thermal
effects. Dynamic effects found in vortex systems include depinning,
nonequilibrium phase transitions, creep, structural order-disorder transitions,
and melting. Understanding vortex dynamics is also important for applications
of superconductors which require the vortices either to remain pinned or to
move in a controlled fashion. Recently, topological defects called skyrmions
have been realized experimentally in chiral magnets. Here we highlight
similarities and differences between skyrmion dynamics and vortex dynamics.
Many of the previous ideas and experimental setups that have been applied to
superconducting vortices can also be used to study skyrmions. We also discuss
some of the differences between the two systems, such as the potentially large
contribution of the Magnus force in the skyrmion system that can dramatically
alter the dynamics and transport properties.


title: Determination of a Type of Permutation Binomials over Finite Fields

abstract:
  Let $f=a\x+\x^{3q-2}\in\Bbb F_{q^2}[\x]$, where $a\in\Bbb F_{q^2}^*$. We
prove that $f$ is a permutation polynomial of $\Bbb F_{q^2}$ if and only if one
of the following occurs: (i) $q=2^e$, $e$ odd, and $a^{\frac{q+1}3}$ is a
primitive $3$rd root of unity. (ii) $(q,a)$ belongs to a finite set which is
determined in the paper.


title:
Micro-wires self-assembled and 3D-connected with the help of a nematic
  liquid crystal

abstract:
  We discuss a method for producing automatic 3D connections at right places
between substrates in front to one another. The idea is based on the
materialization of disclination lines working as templates. The lines are first
created in the nematic liquid crystal (5CB) at the very place where microwires
have to be synthesized. Due to their anchoring properties, colloids dispersed
into the nematic phase produce orientational distortions around them. These
distortions, which may be considered as due to topological charges, result in a
nematic force, able to attract the colloids towards the disclinations.
Ultimately, the particles get trapped onto them, forming micro or
nano-necklaces. Before being introduced in the nematic phase, the colloids are
covered with an adhering and conducting polypyrrole film directly synthesized
at the surface of the particles (heterogeneous polymerization). In this manner,
the particles become conductive so that we may finally perform an
electropolymerization of pyrrole monomers solved in 5CB, and definitely stick
the whole necklace. The electric connection thus synthesized is analyzed by
AFM, and its strength is checked by means of hydrodynamic tests. This wiring
method could allow Moore's law to overcome the limitations that arise when
down-sizing the electronic circuits to nanometer scale.


title:
Cosmological constraints from large-scale structure growth rate
  measurements

abstract:
  We compile a list of $14$ independent measurements of large-scale structure
growth rate between redshifts $0.067 \leq z \leq 0.8$ and use this to place
constraints on model parameters of constant and time-evolving
general-relativistic dark energy cosmologies. With the assumption that gravity
is well-modeled by general relativity, we discover that growth-rate data
provide restrictive cosmological parameter constraints. In combination with
type Ia supernova apparent magnitude versus redshift data and Hubble parameter
measurements, the growth rate data are consistent with the standard
spatially-flat $\Lambda$CDM model, as well as with mildly evolving dark energy
density cosmological models.


title: Comment on "General Non-Markovian Dynamics of Open Quantum Systems"

abstract:
  The existence of a "non-Markovian dissipationless" regime, characterized by
long lived oscillations, was recently reported for a class of quantum open
systems (Zhang et al, PRL, 109, 170402, (2012)). It is claimed this could
happen in the strong coupling regime, a surprising result which has attracted
some attention. We show that this regime exists if and only if the total
Hamiltonian is unbounded from below, casting serious doubts on the usefulness
of this result.


title: The mass of the product of spheres

abstract:
  Any compact manifold with positive scalar curvature has an associated
asymptotically flat metric constructed using the Green's function of the
conformal Laplacian, and the mass of this metric is an important geometric
invariant. An explicit expression for the mass of the product of spheres $S^2
\times S^2$, both with the same Gaussian curvature, is given. Expressions for
the masses of the quotient spaces $G(2,4)$, and $\mathbb{RP}^2 \times
\mathbb{RP}^2$ are also given. The values of these masses arise in a
construction of critical metrics on certain $4$-manifolds; applications to this
problem will also be discussed.


title:
New dynamical scaling universality for quantum networks across adiabatic
  quantum phase transitions

abstract:
  We reveal universal dynamical scaling behavior across adiabatic quantum phase
transitions (QPTs) in networks ranging from traditional spatial systems (Ising
model) to fully connected ones (Dicke and Lipkin-Meshkov-Glick models). Our
findings, which lie beyond traditional critical exponent analysis and adiabatic
perturbation approximations, are applicable even where excitations have not yet
stabilized and hence provide a time-resolved understanding of QPTs encompassing
a wide range of adiabatic regimes. We show explicitly that even though two
systems may traditionally belong to the same universality class, they can have
very different adiabatic evolutions. This implies more stringent conditions
need to be imposed than at present, both for quantum simulations where one
system is used to simulate the other, and for adiabatic quantum computing
schemes.


title: Vortex dynamics in spin-orbit coupled Bose-Einstein condensates

abstract:
  I use a time-dependent Lagrangian formalism and a variational trial function
to study the dynamics of a two-component vortex in a spin-orbit coupled
Bose-Einstein condensate (BEC). For a single-component BEC, various experiments
have validated this theoretical approach, for example a thermal quench that
yields a quantized vortex in roughly 25% of trials. To be definite, I assume
the specific spin-orbit form used in recent NIST experiments, which introduces
a spatial asymmetry because of the external Raman laser beams. I here
generalize this formalism to include a two-component order parameter that has
quantized circulation in each component but not necessarily with the same
circulation. For example a singly quantized vortex in just one component yields
a BEC analog of the half-quantum vortex familiar in $^3$He-A and in $p$-wave
chiral superconductors. This and other unusual two-component vortices have both
periodic trajectories and unbounded trajectories that leave the condensate,
depending on the initial conditions. The optimized phase of the order parameter
induces a term in the particle current that cancels the contribution from the
vector potential, leaving pure circulating current around the vortex.


title:
Traversable wormholes without exotic matter in multimetric repulsive
  gravity

abstract:
  We present a static, spherically symmetric, traversable wormhole solution to
multimetric gravity which is sustained by only non-exotic matter, i.e., matter
which satisfies all energy conditions. The possibility of this solution arises
from the fact that under certain conditions the multimetric gravitational field
equations reduce to the Einstein equations, but with a negative effective
gravitational constant. We show that the Arnowitt-Deser-Misner mass of this
wormhole vanishes, so that it appears massless to observers in the
asymptotically flat spacetime. We finally speculate on the feasibility of
creating and maintaining this type of wormhole by an advanced civilization.


title: Yet another proof of the Morse index theorem

abstract:
  We give a new analytical proof of the Morse index theorem for geodesics in
Riemannian manifolds.


title: Joint probability density functions of random trajectories through a box

abstract:
  A wide range of physical problems can be described by randomly-oriented
linear trajectories, including any system of objects, organisms, particles, or
rays that follow a linear path. Dependent upon the particular random variables
that define translation and direction, a description of the probabilistic
behavior through a static volume can reveal evidence on an object's physical
properties. Yet more information may be available in cases where this behavior
is a function of volume shape. In this study two types of random trajectories
are considered as they pass through a box of arbitrary relative dimension. One
type defines trajectories from uniform random selection of a spatial location
paired with a directional vector; the other is formed from a uniformly
distributed position vector on a surface. The joint probability distributions
for trajectory length as a function of box position are formulated and then
examined for different size boxes, and their physical representations
discussed.


title:
Generalized PDE estimates for KPZ equations through
  Hamilton-Jacobi-Bellman formalism

abstract:
  We study in this series of articles the Kardar-Parisi-Zhang (KPZ) equation $$
\partial_t h(t,x)=\nu\Delta h(t,x)+\lambda V(|\nabla h(t,x)|) +\sqrt{D}\,
\eta(t,x), \qquad x\in{\mathbb{R}}^d $$ in $d\ge 1$ dimensions. The forcing
term $\eta$ in the right-hand side is a regularized white noise. The deposition
rate $V$ is assumed to be isotropic and convex. Assuming $V(0)\ge 0$, one finds
$V(|\nabla h|)\ltimes |\nabla h|^2$ for small gradients, yielding the equation
which is most commonly used in the literature.
  The present article, a continuation of [24], is dedicated to a generalization
of the PDE estimates obtained in the previous article to the case of a
deposition rate $V$ with polynomial growth of arbitrary order at infinity, for
which in general the Cole-Hopf transformation does not allow any more a
comparison to the heat equation. The main tool here instead is the
representation of $h$ as the solution of some minimization problem through the
Hamilton-Jacobi-Bellman formalism. This sole representation turns out to be
powerful enough to produce local or pointwise estimates in ${\cal W}$-spaces of
functions with "locally bounded averages", as in [24], implying in particular
global existence and uniqueness of solutions.


title:
Brown Dwarf Photospheres are Patchy: A Hubble Space Telescope
  Near-infrared Spectroscopic Survey Finds Frequent Low-level Variability

abstract:
  Condensate clouds strongly impact the spectra of brown dwarfs and exoplanets.
Recent discoveries of variable L/T transition dwarfs argued for patchy clouds
in at least some ultracool atmospheres. This study aims to measure the
frequency and level of spectral variability in brown dwarfs and to search for
correlations with spectral type. We used HST/WFC3 to obtain spectroscopic time
series for 22 brown dwarfs of spectral types ranging from L5 to T6 at 1.1-1.7
$\mu$m for $\approx$40 min per object. Using Bayesian analysis, we find 6 brown
dwarfs with confident $(p>95\%)$ variability in the relative flux in at least
one wavelength region at sub-percent precision, and 5 brown dwarfs with
tentative $(p>68\%)$ variability. We derive a minimum variability fraction
$f_{min}=27^{+11}_{-7}\%$ over all covered spectral types. The fraction of
variables is equal within errors for mid L, late L and mid T spectral types;
for early T dwarfs we do not find any confident variable but the sample is too
small to derive meaningful limits. For some objects, the variability occurs
primarily in the flux peak in the J or H band, others are variable throughout
the spectrum or only in specific absorption regions. Four sources may have
broad-band peak-to-peak amplitudes exceeding 1%. Our measurements are not
sensitive to very long periods, inclinations near pole-on and rotationally
symmetric heterogeneity. The detection statistics are consistent with most
brown dwarf photospheres being patchy. While multiple-percent near-infrared
variability may be rare and confined to the L/T transition, low-level
heterogeneities are a frequent characteristic of brown dwarf atmospheres.


title:
The historical development of X-ray Absorption Fine Spectroscopy and of
  its applications to Materials Science

abstract:
  This essay sketches the development of X-ray Absorption Fine Spectroscopy
(XAFS) ever since the second half of 20th century. At that time, synchrotrons
started competing with X-ray discharge tubes as the sources of the excitation
able to show the pre- and near-edge structures (XANES) and extended
oscillations (EXAFS) that characterize the X-ray absorption edge of solid
matter. Actually, modern XAFS began after 1975, when the hard-X-ray synchrotron
radiation derived from storage rings took over. Ever since, XAFS greatly
contributed to both technical refinement and to theoretical development of
Materials Science. Although a unified theory of X-ray fine absorption has not
been reached yet, many XAFS advancements benefited of theoretical models and
complex calculations made possible by the continuous growth of the computing
power, while contributing to developing new or previously never used materials.


title: Frame-like Lagrangians and presymplectic AKSZ-type sigma models

abstract:
  We study supergeometric structures underlying frame-like Lagrangians. We show
that for the theory in n spacetime dimensions both the frame-like Lagrangian
and its gauge symmetries are encoded in the target supermanifold equipped with
the odd vector field, the closed 2-form of ghost degree n-1, and the scalar
potential of ghost degree n. These structures satisfy a set of compatibility
conditions ensuring the gauge invariance of the theory. The Lagrangian and the
gauge symmetries have the same structures as those of AKSZ sigma model so that
frame-like formulation can be seen as its presymplectic generalization. In
contrast to the conventional AKSZ model the generalization allows to describe
systems with local degrees of freedom in terms of finite-dimensional target
space. We argue that the proposed frame-like approach is directly related de
Donder-Weyl polymomentum Hamiltonian formalism. Along with the standard
field-theoretical examples like Einstein-Yang-Mills theory we consider free
higher spin fields, multi-frame gravity, and parameterized systems. In
particular, we propose the frame-like action for free totally symmetric
massless fields that involves all higher spin connections on an equal footing.


title:
Tweet, but Verify: Epistemic Study of Information Verification on
  Twitter

abstract:
  While Twitter provides an unprecedented opportunity to learn about breaking
news and current events as they happen, it often produces skepticism among
users as not all the information is accurate but also hoaxes are sometimes
spread. While avoiding the diffusion of hoaxes is a major concern during
fast-paced events such as natural disasters, the study of how users trust and
verify information from tweets in these contexts has received little attention
so far. We survey users on credibility perceptions regarding witness pictures
posted on Twitter related to Hurricane Sandy. By examining credibility
perceptions on features suggested for information verification in the field of
Epistemology, we evaluate their accuracy in determining whether pictures were
real or fake compared to professional evaluations performed by experts. Our
study unveils insight about tweet presentation, as well as features that users
should look at when assessing the veracity of tweets in the context of
fast-paced events. Some of our main findings include that while author details
not readily available on Twitter feeds should be emphasized in order to
facilitate verification of tweets, showing multiple tweets corroborating a fact
misleads users to trusting what actually is a hoax. We contrast some of the
behavioral patterns found on tweets with literature in Psychology research.


title: From Lattice Strong Dynamics to Phenomenology

abstract:
  We present updated results on the chiral properties of SU(3) gauge theories
with 2 and 6 massless Dirac fermions in the fundamental representation. Our
focus is on the ratio $\langle \bar{\psi} \psi \rangle / F^3$, where $\langle
\bar{\psi} \psi \rangle$ is the chiral condensate and $F$ is the
pseudo-Nambu-Goldstone-boson decay constant. This ratio is of interest in the
context of fermion mass generation within composite Higgs theories. By
re-expanding certain ratios using next-to-leading-order chiral perturbation
theory, we confirm our previous result of significant enhancement of this ratio
at $N_f = 6$ over $N_f = 2$.


title: Commutation Relations for Unitary Operators III

abstract:
  Let $U$ be a unitary operator defined on some infinite-dimensional complex
Hilbert space ${\cal H}$. Under some suitable regularity assumptions, it is
known that a local positive commutation relation between $U$ and an auxiliary
self-adjoint operator $A$ defined on ${\cal H}$ allows to prove that the
spectrum of $U$ has no singular continuous spectrum and a finite point
spectrum, at least locally. We prove that under stronger regularity hypotheses,
the local regularity properties of the spectral measure of $U$ are improved,
leading to a better control of the decay of the correlation functions. As shown
in the applications, these results may be applied to the study of periodic
time-dependent quantum systems, classical dynamical systems and spectral
problems related to the theory of orthogonal polynomials on the unit circle.


title:
Asbestiform tremolite within the Holocene late pyroclastic deposits of
  Colli Albani volcano (Latium, Italy): Occurrence and crystal-chemistry

abstract:
  This work relates the occurrence and the characterization of fibrous
tremolite within the latest pyroclastic deposits of the Colli Albani (Alban
Hills) volcano, to the south-east of Rome (Italy). These mineralizations were
observed during a systematic rock-sampling undertaken to complete the
geological survey for the new 1:50 000 map of this volcanic area. The examined
specimens were collected inside distal deposits correlated to the last Albano
Maar activity, which are geographically located within the boundaries of the
Nemi community. Tremolite occurs within both carbonate ejecta and the host
pyroclastic rocks. It shows up as whitish to light gray coloured aggregates of
crystals with fibrous aspect and sericeous brightness. Due to the extremely
small crystal dimensions, never exceeding 0.5 micron in diameter, the
micro-chemical composition of the fibres could be obtained only by combining
P-XRD, SEM-EDX and FTIR methods. Infrared spectroscopy, in particular, proved
to be a valuable technique to characterize the studied amphibole. The
composition determined is that of a Fe-free F-rich (c. 53%) tremolite with
significant (c. 20%) richterite components in solid-solution. The occurrence of
fibrous tremolite in an inhabited place, occurring as natural geological
material rather than being due to anthropogenic pollution, should be examined
with concern, because it implies complex health and legal responsibilities in
the case of mobilization due to extreme climatic events.


title: The effective gravitational decoupling between dark matter and the CMB

abstract:
  We present a detailed and self-contained analytical derivation of the
evolution of sub-horizon cosmological perturbations before decoupling, based on
previous work by S. Weinberg. These solutions are valid in the minimal LCDM
scenario, to first order in perturbation theory, in the tight-coupling limit
and neglecting neutrino shear stress. We compare them to exact numerical
solutions computed by a Boltzmann code, and we find the two to be in very good
agreement. The analytic solutions show explicitly that CDM and the
baryon-photon fluid effectively behave as separate self-gravitating fluids
until the epoch of baryon drag. This in turn leads to the surprising conclusion
that the CMB is much less sensitive to the clustering properties of minimally
coupled Dark Matter models than what would be naively expected.


title:
Parallel coordinate descent methods for composite minimization:
  convergence analysis and error bounds

abstract:
  In this paper we propose a distributed version of a randomized
block-coordinate descent method for minimizing the sum of a partially separable
smooth convex function and a fully separable non-smooth convex function. Under
the assumption of block Lipschitz continuity of the gradient of the smooth
function, this method is shown to have a sublinear convergence rate. Linear
convergence rate of the method is obtained for the newly introduced class of
generalized error bound functions. We prove that the new class of generalized
error bound functions encompasses both global/local error bound functions and
smooth strongly convex functions. We also show that the theoretical estimates
on the convergence rate depend on the number of blocks chosen randomly and a
natural measure of separability of the objective function.


title: Reconfigurable long-range phonon dynamics in optomechanical arrays

abstract:
  We investigate periodic optomechanical arrays as reconfigurable platforms for
engineering the coupling between multiple mechanical and electromagnetic modes
and for exploring many-body phonon dynamics. Exploiting structural resonances
in the coupling between light fields and collective motional modes of the
array, we show that tunable effective long-range interactions between
mechanical modes can be achieved. This paves the way towards the implementation
of controlled phononic walks and heat transfer on densely-connected graphs as
well as the coherent transfer of excitations between distant elements of
optomechanical arrays.


title: Long-distance effects in charm mixing

abstract:
  I review challenges in the understanding of long distance effects in
theoretical calculations of mixing rates of charmed mesons in the standard
model.


title: A Skolem-Mahler-Lech theorem for iterated automorphisms of $K$-algebras

abstract:
  This paper proves a commutative algebraic extension of a generalized
Skolem-Mahler-Lech theorem due to the first author. Let $A$ be a finitely
generated commutative $K$-algebra over a field of characteristic $0$, and let
$\sigma$ be a $K$-algebra automorphism of $A$. Given ideals $I$ and $J$ of $A$,
we show that the set $S$ of integers $m$ such that $\sigma^m(I) \supseteq J$ is
a finite union of complete doubly infinite arithmetic progressions in $m$, up
to the addition of a finite set. Alternatively, this result states that for an
affine scheme $X$ of finite type over $K$, an automorphism $\sigma \in {\rm
Aut}_K(X)$, and $Y$ and $Z$ any two closed subschemes of $X$, the set of
integers $m$ with $\sigma^m(Z ) \subseteq Y$ is as above. The paper presents
examples showing that this result may fail to hold if the affine scheme $X$ is
not of finite type, or if $X$ is of finite type but the field $K$ has positive
characteristic.


title: Network histograms and universality of blockmodel approximation

abstract:
  In this article we introduce the network histogram: a statistical summary of
network interactions, to be used as a tool for exploratory data analysis. A
network histogram is obtained by fitting a stochastic blockmodel to a single
observation of a network dataset. Blocks of edges play the role of histogram
bins, and community sizes that of histogram bandwidths or bin sizes. Just as
standard histograms allow for varying bandwidths, different blockmodel
estimates can all be considered valid representations of an underlying
probability model, subject to bandwidth constraints. Here we provide methods
for automatic bandwidth selection, by which the network histogram approximates
the generating mechanism that gives rise to exchangeable random graphs. This
makes the blockmodel a universal network representation for unlabeled graphs.
With this insight, we discuss the interpretation of network communities in
light of the fact that many different community assignments can all give an
equally valid representation of such a network. To demonstrate the
fidelity-versus-interpretability tradeoff inherent in considering different
numbers and sizes of communities, we analyze two publicly available networks -
political weblogs and student friendships - and discuss how to interpret the
network histogram when additional information related to node and edge labeling
is present.


title: Seeking Anonymity in an Internet Panopticon

abstract:
  Obtaining and maintaining anonymity on the Internet is challenging. The state
of the art in deployed tools, such as Tor, uses onion routing (OR) to relay
encrypted connections on a detour passing through randomly chosen relays
scattered around the Internet. Unfortunately, OR is known to be vulnerable at
least in principle to several classes of attacks for which no solution is known
or believed to be forthcoming soon. Current approaches to anonymity also appear
unable to offer accurate, principled measurement of the level or quality of
anonymity a user might obtain.
  Toward this end, we offer a high-level view of the Dissent project, the first
systematic effort to build a practical anonymity system based purely on
foundations that offer measurable and formally provable anonymity properties.
Dissent builds on two key pre-existing primitives - verifiable shuffles and
dining cryptographers - but for the first time shows how to scale such
techniques to offer measurable anonymity guarantees to thousands of
participants. Further, Dissent represents the first anonymity system designed
from the ground up to incorporate some systematic countermeasure for each of
the major classes of known vulnerabilities in existing approaches, including
global traffic analysis, active attacks, and intersection attacks. Finally,
because no anonymity protocol alone can address risks such as software exploits
or accidental self-identification, we introduce WiNon, an experimental
operating system architecture to harden the uses of anonymity tools such as Tor
and Dissent against such attacks.


title:
Primordial Magnetic Field Limits from CMB Trispectrum - Scalar Modes and
  Planck Constraints

abstract:
  Cosmic magnetic fields are observed to be coherent on large scales and could
have a primordial origin. Non-Gaussian signals in the cosmic microwave
background (CMB) are generated by primordial magnetic fields as the magnetic
stresses and temperature anisotropy they induce depend quadratically on the
magnetic field. We compute the CMB scalar trispectrum on large angular scales,
for nearly scale-invariant magnetic fields, sourced via the Sachs-Wolfe effect.
The trispectra induced by magnetic energy density and by magnetic scalar
anisotropic stress are found to have typical magnitudes of approximately
$10^{-29}$ and $10^{-19}$, respectively. The scalar anisotropic stress
trispectrum is also calculated in the flat-sky approximation and yields a
similar result. Observational limits on CMB non-Gaussianity from the Planck
mission data allow us to set upper limits of $B_0 \lesssim 0.6 $ nG on the
present value of the primordial cosmic magnetic field. Considering the
inflationary magnetic curvature mode in the trispectrum can further tighten the
magnetic field upper limit to $B_0 \lesssim 0.05 $ nG. These sub-nanoGauss
constraints from the magnetic trispectrum are the most stringent limits so far
on the strength of primordial magnetic fields, on megaparsec scales,
significantly better than the limits obtained from the CMB bispectrum and the
CMB power spectrum.


title: Observable physical modes of modified gravity

abstract:
  At linear order in cosmological perturbations, departures from the growth in
the cosmological standard model can be quantified in terms of two functions of
redshift $z$ and Fourier number $k$. Previous studies have performed principal
component forecasts for several choices of these two functions, based on
expected capabilities of upcoming large structure surveys. It is typically
found that there will be many well-constrained degrees of freedom. However, not
all and, probably most, of these degrees of freedom were physical if the
parametrization had allowed for an arbitrary $k$-dependence. In this paper, we
restrict the $k$-dependence to that allowed in local theories of gravity under
the quasi-static approximation, i.e. ratios of polynomials in $k$, and identify
the best constrained features in the ($z$,$k$)-dependence of the commonly
considered functions $\mu$ and $\gamma$ as measured by an LSST-like weak
lensing survey. We estimate the uncertainty in the measurements of the
eigenmodes of modified growth. We find that imposing the theoretical prior on
$k$-dependence reduces the number of degrees of freedom and the covariance
between parameters. On the other hand, imaging surveys like LSST are not as
sensitive to the $z$-dependence as they are to the $k$-dependence of the
modified growth functions. This trade off provides us with, more or less, the
same number of well-constrained eigenmodes (with respect to our prior) as found
before, but now these modes are physical.


title:
Simulated star formation rate functions at z~4-7, and the role of
  feedback in high-z galaxies

abstract:
  We study the role of feedback from supernovae and black holes in the
evolution of the star formation rate function (SFRF) of z~4-7 galaxies. We use
a new set of cosmological hydrodynamic simulations, ANGUS (AustraliaN GADGET-3
early Universe Simulations), run with a modified and improved version of the
parallel TreePM-smoothed particle hydrodynamics code GADGET-3 called
P-GADGET3(XXL), that includes a self-consistent implementation of stellar
evolution and metal enrichment. In our simulations both Supernova (SN) driven
galactic winds and Active Galactic Nuclei (AGN) act simultaneously in a complex
interplay. The SFRF is insensitive to feedback prescription at z>5, meaning
that it cannot be used to discriminate between feedback models during
reionisation. However, the SFRF is sensitive to the details of feedback
prescription at lower redshift. By exploring different SN driven wind
velocities and regimes for the AGN feedback, we find that the key factor for
reproducing the observed SFRFs is a combination of "strong" SN winds and early
AGN feedback in low mass galaxies. Conversely, we show that the choice of
initial mass function and inclusion of metal cooling have less impact on the
evolution of the SFRF. When variable winds are considered, we find that a
non-aggressive wind scaling is needed to reproduce the SFRFs at z>4. Otherwise,
the amount of objects with low SFRs is greatly suppressed and at the same time
winds are not effective enough in the most massive systems.


title:
Sliding not sloshing in Abell 3744: the influence of radio galaxies NGC
  7018 and 7016 on cluster gas

abstract:
  We present new X-ray (Chandra) and radio (JVLA) observations of the nearby
cluster Abell 3744. It hosts two prominent radio galaxies with powers in the
range critical for radio-mode feedback. The radio emission from these galaxies
terminates in buoyant tendrils reaching the cluster's outer edge, and the
radio-emitting plasma clearly influences the cluster's X-ray-emitting
atmosphere. The cluster's average gas temperature, of kT=3.5 keV, is high for
its bolometric luminosity of 3.2 \times 10^{43} ergs s^{-1}, but the 100
kpc-scale cavity carved out by radio-emitting plasma shows evidence of less
than 2 per cent of the excess enthalpy. We suggest instead that a high-velocity
encounter with a galaxy group is responsible for dispersing and increasing the
entropy of the gas in this non-cool-core cluster. We see no evidence for
shocks, or established isobaric gas motions (sloshing), but there is much
sub-structure associated with a dynamically active central region that
encompasses the brightest radio emission. Gas heating is evident in directions
perpendicular to the inferred line of encounter between the infalling group and
cluster. The radio-emitting tendrils run along boundaries between gas of
different temperature, apparently lubricating the gas flows and inhibiting heat
transfer. The first stages of the encounter may have helped trigger the radio
galaxies into their current phase of activity, where we see X-rays from the
nuclei, jets, and hotspots.


title: Real-Space Visualization of Remnant Mott Gap and Magnon Excitations

abstract:
  We demonstrate the ability to visualize real-space dynamics of charge gap and
magnon excitations in the Mott phase of the single-band Hubbard model and the
remnants of these excitations with hole or electron doping. At short times, the
character of magnetic and charge excitations is maintained even for large
doping away from the Mott and antiferromagnetic phases. Doping influences both
the real-space patterns and long timescales of these excitations with a clear
carrier asymmetry attributable to particle-hole symmetry breaking in the
underlying model. Further, a rapidly-oscillating charge density wave-like
pattern weakens, but persists as a visible demonstration of a sub-leading
instability at half-filling which remains upon doping. The results offer an
approach to analyzing the behavior of systems where momentum-space is either
inaccessible or poorly defined.


title:
Synchrotron radiation, pair production and longitudinal electron motion
  during 10-100PW laser solid interactions

abstract:
  At laser intensities above 1023W/cm2 the interaction of a laser with a plasma
is qualitatively different to the interactions at lower intensities. In this
intensity regime solid targets start to become relativistically underdense,
gamma-ray production by synchrotron emission starts to become an important
feature of the dynamics and, at even higher intensities, electron-positron pair
production by the non-linear Breit-Wheeler process starts to occur. Previous
work in this intensity regime has considered ion acceleration1,2, identified
different mechanisms for the underlying plasma physics of laser generation of
gamma-rays3,4,5 considered the effect of target parameters on gamma-ray
generation6 and considered the creation of solid density positronium plasma3.
However a complete linked understanding of the important new physics of this
regime is still lacking. In this paper, an analysis is presented of the effects
of target density, laser intensity, target preplasma properties and other
parameters on the conversion efficiency, spectrum and angular distribution of
gamma-rays by synchrotron emission. An analysis of the importance of
Breit-Wheeler pair production is also presented.


title:
Hyperaccretion during tidal disruption events: weakly bound debris
  envelopes and jets

abstract:
  After the destruction of the star during a tidal disruption event (TDE), the
cataclysmic encounter between a star and the supermassive black hole (SMBH) of
a galaxy, approximately half of the original stellar debris falls back onto the
hole at a rate that can initially exceed the Eddington limit by orders of
magnitude. We argue that the angular momentum of this matter is too low to
allow it to attain a disk-like configuration with accretion proceeding at a
mildly super-Eddington rate, the excess energy being carried away by a
combination of radiative losses and radially distributed winds. Instead, we
propose that the infalling gas traps accretion energy until it inflates into a
weakly-bound, quasi-spherical structure with gas extending nearly to the poles.
We study the structure and evolution of such "Zero-Bernoulli accretion" flows
(ZEBRAs) as a model for the super-Eddington phase of TDEs. We argue that such
flows cannot stop extremely super-Eddington accretion from occurring, and that
once the envelope is maximally inflated, any excess accretion energy escapes
through the poles in the form of powerful jets. We compare the predictions of
our model to Swift J1644+57, the putative super-Eddington TDE, and show that it
can qualitatively reproduce some of its observed features. Similar models,
including self-gravity, could be applicable to gamma-ray bursts from collapsars
and the growth of supermassive black hole seeds inside quasi-stars.


title: Discovery of the Fomalhaut C debris disc

abstract:
  Fomalhaut is one of the most interesting and well studied nearby stars,
hosting at least one planet, a spectacular debris ring, and two distant
low-mass stellar companions (TW PsA and LP 876-10, a.k.a. Fomalhaut B & C). We
observed both companions with Herschel, and while no disc was detected around
the secondary, TW PsA, we have discovered the second debris disc in the
Fomalhaut system, around LP 876-10. This detection is only the second case of
two debris discs seen in a multiple system, both of which are relatively wide
($\gtrsim$3000 AU for HD 223352/40 and 158 kAU [0.77 pc] for Fomalhaut/LP
876-10). The disc is cool (24K) and relatively bright, with a fractional
luminosity $L_{\rm disc}/L_\star = 1.2 \times 10^{-4}$, and represents the rare
observation of a debris disc around an M dwarf. Further work should attempt to
find if the presence of two discs in the Fomalhaut system is coincidental,
perhaps simply due to the relatively young system age of 440 Myr, or if the
stellar components have dynamically interacted and the system is even more
complex than it currently appears.


title: Constraints on composite quark partners from Higgs searches

abstract:
  In composite Higgs models, the generation of quark masses requires the
standard model-like quarks to be partially or fully composite states which are
accompanied by composite quark partners. The composite quark partners decay
into a standard model-like quark and an electroweak gauge boson or Higgs boson,
which can be searched for at the LHC. In this article, we study the
phenomenological implications of composite quarks in the minimal composite
Higgs model based on the coset $SO(5)/SO(4)$. We focus on light quark partners
which are embedded in the $SO(4)$ singlet representation. In this case, a
dominant decay mode of the partner quark is into a Higgs boson and a jet, for
which no experimental bounds have been established so far. The presence of
$SO(4)$ singlet partners leads to an enhancement of the di-Higgs production
cross section at the LHC. This will be an interesting experimental signature in
the near future, but, unfortunately, there are no direct bounds available yet
from the experimental analyses. However, we find that the currently available
standard model-like Higgs searches can be used in order to obtain the first
constraints on partially and fully composite quark models with light quark
partners in the $SO(4)$ singlet. We obtain a flavor- and composition parameter
independent bound on the quark partner mass of $M_{U_h} > 310 \mbox{ GeV}$ for
partially composite quark models and $M_{U_h} > 212 \mbox{ GeV}$ for fully
composite quark models.


title: Constraints on the merging channel of massive galaxies since z~1

abstract:
  (Abridged) We probe the merging channel of massive galaxies over the
z=0.3-1.3 redshift window by studying close pairs in a sample of 238 galaxies
with stellar mass >1E11Msun, from the deep (m<26.5AB, 3 sigma) SHARDS survey.
SHARDS provides medium band photometry equivalent to low-resolution optical
spectra (R~50), allowing us to obtain extremely accurate photometric redshifts
(|Dz|/(1+z)~0.55%) and to improve the constraints on the age distribution of
the stellar populations. A strong correlation is found between the age
difference of central and satellite galaxy and stellar mass ratio, from
negligible age differences in major mergers to age differences ~4 Gyr for 1:100
minor mergers. However, this correlation is simply a reflection of the mass-age
trend in the general population. The dominant contributor to the growth of
massive galaxies corresponds to mass ratios mu=Msat/Mcen>0.3, followed by a
decrease in the fractional mass growth rate linearly proportional to log mu, at
least down to mu~0.01, suggesting a decreasing role of mergers involving
low-mass satellites, especially if dynamical friction timescales are taken into
account. A simple model results in an upper limit for the average mass growth
rate of massive galaxies of DM/M/Dt~ 0.08+-0.02 per Gyr, over the z<1 range,
with a ~70% fractional contribution from (major) mergers with mu>0.3. The
majority of the stellar mass contributed by mergers does not introduce
significantly younger populations, in agreement with the small radial age
gradients observed in present-day early-type galaxies.


title: Decoupling of heavy sneutrinos in low-scale seesaw models

abstract:
  There have been some recent claims in the literature about large right-handed
sneutrinos contributions to lepton flavor violating observables like $\mu \to
3e$ or $\mu - e$ conversion in nuclei in supersymmetric low-scale seesaw
models. These large contributions originate from $Z$-penguin diagrams which
show a much weaker dependence on the heavy masses than the photonic
contributions. We have traced this to an error in the evaluation of the
corresponding loop amplitudes which has propagated in the literature. We
explicitly show that after correcting this mistake the $Z$-penguins show the
expected decoupling behavior. Moreover, the reported dominance of the
$Z$-penguin over the photonic contributions disappears as well.


title: Spin-current autocorrelations from single pure-state propagation

abstract:
  We demonstrate that the concept of quantum typicality allows for significant
progress in the study of real-time spin dynamics and transport in quantum
magnets. To this end, we present a numerical analysis of the spin-current
autocorrelation function of the antiferromagnetic and anisotropic spin-1/2
Heisenberg chain as inferred from propagating only a single pure state,
randomly chosen as a "typical" representative of the statistical ensemble.
Comparing with existing time-dependent density-matrix renormalization group
(tDMRG) data, we show that typicality is fulfilled extremely well, consistent
with an error of our approach, which is perfectly under control and vanishes in
the thermodynamic limit. In the long-time limit, our results provide for a new
benchmark for the enigmatic spin Drude weight, which we obtain from chains as
long as L=33 sites, i.e., from Hilbert spaces of dimensions almost O(10^4)
larger than in existing exact-diagonalization studies.


title: Metal-free galaxy candidates discovered in CLASH

abstract:
  The first metals in the universe are expected to form in population III stars
- primordial stars consisting entirely of hydrogen and helium. However, these
stars have so far remained elusive. Simulations indicate that galaxies
consisting exclusively, or almost exclusively, of population III stars may form
at z>6, and such galaxies may provide one of the best probes of the properties
of the population III star formation mode. By fitting Yggdrasil model spectra
to multiband photometry data, we have identified four population III galaxy
candidates in the Cluster Lensing and Supernova survey with Hubble (CLASH). We
rule out alternative mundane galaxies and low redshift interlopers through
similar fits to catalogs of spectra from more mundane objects. If confirmed
through spectroscopy, this would constitute the first detection of the "missing
link" between the early pristine universe and the metal-enriched universe.


title: Metal abundances in the high-redshift intergalactic medium

abstract:
  Twenty years of high-resolution spectroscopy at the 8-10 m class telescopes
have drastically expanded our view of the gas-phase metallicity in the z>2
universe. This contribution briefly summarizes how these studies reveal a
widespread metal pollution in the intergalactic medium with a median abundance
[C/H] ~ -3.5 at z~3 that is increasing by a factor of ~2-3 from z~4.3 to z~2.4.
At the higher densities that are typical of galactic halos, observations
uncover a metallicity spread of five orders of magnitude in Lyman limit
systems, ranging from super-solar ([M/H]~+0.7) to pristine ([M/H]< -4) gas
clouds. Finally, the neutral damped Ly-alpha systems are enriched to a median
metallicity of [M/H] ~ -1.5 that slowly declines with redshift up to z ~ 4.5,
at which point it appears to more rapidly evolve as one approaches the end of
reionization.


title:
Decay of Bogoliubov quasiparticles in a nonideal one-dimensional Bose
  gas

abstract:
  We study the relaxation of excitations in a system of one-dimensional weakly
interacting bosons. Due to residual weak interactions, Bogoliubov
quasiparticles in this system have finite lifetimes. As a result of the
conservation laws in one dimension, at zero temperature the leading mechanism
of decay of a quasiparticle is disintegration into three others. We focus on
phonon quasiparticles and find that their decay rate is proportional to the
seventh power of momentum. In the integrable case of contact interaction
between the bosons, the decay rate vanishes.


title:
Holographic thermalization, quasinormal modes and superradiance in
  Kerr-AdS

abstract:
  Black holes in anti-de Sitter (AdS) backgrounds play a pivotal role in the
gauge/gravity duality where they determine, among other things, the approach to
equilibrium of the dual field theory. We undertake a detailed analysis of
perturbed Kerr-AdS black holes in four- and five-dimensional spacetimes,
including the computation of its quasinormal modes, hydrodynamic modes and
superradiantly unstable modes. Our results shed light on the possibility of new
black hole phases with a single Killing field, possible new holographic
phenomena and phases in the presence of a rotating chemical potential, and
close a crucial gap in our understanding of linearized perturbations of black
holes in anti-de Sitter scenarios.


title:
Constraining the Variation in Fine-Structure Constant Using SDSS DR8 QSO
  Spectra

abstract:
  We report a robust constrain on the possible variation of fine-structure
constant, alpha = e^2/(hbar*c), obtained using O III 4959,5007, nebular
emission lines from QSOs. We find Delta-alpha/alpha=-(2.1 +/- 1.6) x 10^(-5)
based on a well selected sample of 2347 QSOs from Sloan Digital Sky Survey Data
Release 8 with 0.02 < z < 0.74. Our result is consistent with a non-varying
alpha at a level of 2 x 10^(-5) over approximately 7 Gyr. This is the largest
sample of extragalactic objects yet used to constrain the variation of alpha.
While this constraint is not as stringent as those determined using
many-multiplet method it is free from various systematic effects. A factor of ~
4 improvement in Delta-alpha/alpha achieved here compared to the previous study
(Bahcall et al. 2004) is just consistent with what is expected based on a
factor of 14 times bigger sample used here. This suggests that errors are
mainly dominated by the statistical uncertainty. We also find the ratio of
transition probabilities corresponding to the O III 5007 A and 4959 A lines to
be 2.933+/-0.002, in good agreement with the National Institute of Standards
and Technology measurements.


title: Identifying dark matter interactions in monojet searches

abstract:
  We study the discrimination of quark-initiated jets from gluon-initiated jets
in monojet searches for dark matter using the technique of averaged jet energy
profiles. We demonstrate our results in the context of effective field theories
of dark matter interactions with quarks and gluons, but our methods apply more
generally to a wide class of models. Different effective theories of dark
matter and the standard model backgrounds each have a characteristic
quark/gluon fraction for the leading jet. When used in conjunction with the
traditional cut-and-count monojet search, the jet energy profile can be used to
set stronger bounds on contact interactions of dark matter. In the event of a
discovery of a monojet excess at the 14 TeV LHC, contact interactions between
dark matter with quarks or with gluons can be differentiated at the 95%
confidence level. For a given rate at the LHC, signal predictions at direct
detection experiments for different dark matter interactions can span five
orders of magnitude. The ability to identify these interactions allows us to
make a tighter connection between LHC searches and direct detection
experiments.


title: The Origin and Universality of the Stellar Initial Mass Function

abstract:
  We review current theories for the origin of the Stellar Initial Mass
Function (IMF) with particular focus on the extent to which the IMF can be
considered universal across various environments. To place the issue in an
observational context, we summarize the techniques used to determine the IMF
for different stellar populations, the uncertainties affecting the results, and
the evidence for systematic departures from universality under extreme
circumstances. We next consider theories for the formation of prestellar cores
by turbulent fragmentation and the possible impact of various thermal,
hydrodynamic and magneto-hydrodynamic instabilities. We address the conversion
of prestellar cores into stars and evaluate the roles played by different
processes: competitive accretion, dynamical fragmentation, ejection and
starvation, filament fragmentation and filamentary accretion flows, disk
formation and fragmentation, critical scales imposed by thermodynamics, and
magnetic braking. We present explanations for the characteristic shapes of the
Present-Day Prestellar Core Mass Function and the IMF and consider what
significance can be attached to their apparent similarity. Substantial
computational advances have occurred in recent years, and we review the
numerical simulations that have been performed to predict the IMF directly and
discuss the influence of dynamics, time-dependent phenomena, and initial
conditions.


title: Enhanced non-perturbative effects through the collinear anomaly

abstract:
  We show that non-perturbative effects are logarithmically enhanced for
transverse-momentum-dependent observables such as q_T-spectra of electroweak
bosons in hadronic collisions and jet broadening at e^+e^- colliders. This
enhancement arises from the collinear anomaly, a mechanism characteristic for
transverse observables, which induces logarithmic dependence on the hard scale
in the product of the soft and collinear matrix elements. Our analysis is based
on an operator product expansion and provides, for the first time, a
systematic, model-independent way to study non-perturbative effects for this
class of observables. For the case of jet broadening, we relate the leading
correction to the non-perturbative shift of the thrust distribution.


title: De Sitter Vacua from Non-perturbative Flux Compactifications

abstract:
  We present stable de Sitter solutions of $\mathcal{N} = 1$ supergravity in a
geometric type IIB duality frame with the addition of non-perturbative
contributions. Contrary to the standard approach, we retain the moduli
dependence of both the tree level superpotential and its non-perturbative
contribution. This provides the possibility for a single-step stabilisation of
all moduli simultaneously in a de Sitter vacuum. Using a genetic algorithm we
find explicit solutions with different features.


title: Vector-like leptons: Higgs decays and collider phenomenology

abstract:
  We study the impact of heavy vector-like leptons on several observables in
collider and low-energy physics. These states, present in many well-motivated
extensions of the Standard Model, can induce lepton flavour violation and
non-standard Higgs decays. We study these effects in an effective model
inspired by the composite Higgs scenario. After deriving bounds on the mass and
production cross-section of the vector-like states using recent LHC data on
multilepton searches, we discuss the modification of the Higgs decays to
dilepton, diphoton and $Z\gamma$ final states as well as low-energy observables
like radiative lepton decays, the anomalous magnetic moment of the muon and the
electric dipole moment of the electron. We find several interesting
correlations. In particular, we show that branching fractions of lepton
flavour-violating Higgs decays at an observable level are prohibited due to the
strong bounds on the radiative lepton decays.


title: Fermionic UV completions of Composite Higgs models

abstract:
  We classify the four-dimensional purely fermionic gauge theories that give a
UV completion of composite Higgs models. Our analysis is at the group
theoretical level, addressing the necessary (but not sufficient) conditions for
the viability of these models, such as the existence of top partners and
custodial symmetry. The minimal cosets arising are those of type SU(5)/SO(5)
and SU(4)/Sp(4). We list all the possible "hyper-color" groups allowed and
point out the simplest and most promising ones.


title: An alternative to anti-branes and O-planes?

abstract:
  In this paper we consider type IIA compactifications in the isotropic Z2 x Z2
orbifold with a flux-induced perturbative superpotential combined with
non-perturbative effects. Without requiring the presence of O-planes, and
simply having D6-branes as local sources, we demonstrate the existence of de
Sitter (dS) critical points, where the non-perturbative contributions to the
cosmological constant have negligible size. We note, however, that these
solutions generically have tachyons. By means of a more systematic search, we
are able to find two examples of stable dS vacua with no need for anti-branes
or O-planes, which, however, exhibit important non-perturbative corrections.
The examples that we present turn out to remain stable even after opening up
the fourteen non-isotropic moduli.


title: The Einstein-Klein-Gordon-AdS system for general boundary conditions

abstract:
  We construct unique local solutions for the spherically-symmetric
Einstein-Klein-Gordon-AdS system subject to a large class of initial and
boundary conditions including some considered in the context of the AdS-CFT
correspondence. The proof relies on estimates developed for the linear wave
equation by the second author and involves a careful renormalization of the
dynamical variables, including a renormalization of the well-known Hawking
mass. For some of the boundary conditions considered this system is expected to
exhibit rich global dynamics, including the existence of hairy black holes. The
present paper furnishes a starting point for such global investigations.


title: Is There a Hidden Principle in the Higgs Boson Decay to Photons?

abstract:
  It is remarkable that the measured Higgs boson mass is so close to the value
which maximizes the Higgs decay rate to photons as predicted by the Standard
Model. In this work we explore the consequences to assume that an $\sim 125$
GeV Higgs boson mass is not accidental, but fixed by some fundamental principle
that enforces it to maximize its decay rate into photons. The principle is
motivated by the evidence that only a very small volume of the parameters space
of the Standard Model, which contains their measured values, could lead to a
maximal Higgs boson with that mass. If the principle actually holds, several
Standard Model features get fixed, as the number of fermion families, quark
colors, and the CP nature of the new boson, for example. We also illustrate how
such principle can place strong bounds on new physics scenarios as a Higgs dark
portal model and a Two Higgs Doublet Model.


title: The Astrophysics Source Code Library: Where do we go from here?

abstract:
  The Astrophysics Source Code Library, started in 1999, has in the past three
years grown from a repository for 40 codes to a registry of over 700 codes that
are now indexed by ADS. What comes next? We examine the future of the ASCL, the
challenges facing it, the rationale behind its practices, and the need to
balance what we might do with what we have the resources to accomplish.


title: Novel Higgs Potentials from Gauge Mediation of Exact Scale Breaking

abstract:
  We present a gauge mediation principle for BSM theories where exact UV scale
invariance is broken in a hidden sector. The relevant configurations are those
in which the Standard Model and a hidden sector emanate from a scale invariant
pair of UV theories that communicate only via gauge interactions. We compute
the radiatively induced Higgs potential which contains logarithmic mass-squared
terms that lead to unusual Higgs self-couplings. Its other couplings are
unchanged.


title:
Quantum spectral curve for the Gromov-Witten theory of the complex
  projective line

abstract:
  We construct the quantum curve for the Gromov-Witten theory of the complex
projective line.


title:
Existence results for compressible radiation hydrodynamics equations
  with vacuum

abstract:
  In this paper, we consider the 3-D compressible isentropic radiation
hydrodynamics (RHD) equations. The local existence of strong solutions with
vacuum is firstly established when the initial data is arbitrarily large,
contains vacuum and satisfy some initial layer compatibility condition. The
initial mass density needs not be bounded away from zero, it may vanish in some
open set or decay at infinity. We also prove that if the initial vacuum is not
so irregular, then the compatibility condition of the initial data is necessary
and sufficient to guarantee the existence of a unique strong solution. Finally,
we prove a blow-up criterion for the local strong solution. The similar result
also holds for the general barotropic flow with pressure law $p_m=p_m(\rho)\in
C^1(\mathbb{\overline{R}}^+)$.


title: Cyclic electric field stress on bipolar resistive switching devices

abstract:
  We have studied the effects of accumulating cyclic electrical pulses of
increasing amplitude on the non-volatile resistance state of interfaces made by
sputtering a metal (Au, Pt) on top of the surface of a cuprate superconductor
YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO). We have analyzed the influence of the
number of applied pulses $N$ on the relative amplitude of the remnant
resistance change between the high ($R_H$) and the low ($R_L$) state
[$\alpha=(R_{H}-R_{L})/R_{L}$] at different temperatures ($T$). We show that
the critical voltage ($V_c$) needed to produce a resistive switching (RS, i.e.
$\alpha >0$) decreases with increasing $N$ or $T$. We also find a power law
relation between the voltage of the pulses and the number of pulses
$N_{\alpha_0}$ required to produce a RS of $\alpha=\alpha_0$. This relation
remains very similar to the Basquin equation used to describe the
stress-fatigue lifetime curves in mechanical tests. This points out to the
similarity between the physics of the RS, associated with the diffusion of
oxygen vacancies induced by electrical pulses, and the propagation of defects
in materials subjected to repeated mechanical stress.


title: Hidden charm molecules in a Finite Volume

abstract:
  In the present paper we address the interaction of charmed mesons in hidden
charm channels in a finite box. We use the interaction from a recent model
based on heavy quark spin symmetry that predicts molecules of hidden charm in
the infinite volume. The energy levels in the box are generated within this
model, and several methods for the analysis of these levels ("inverse problem")
are investigated.


title:
Structural and metal-insulator transitions in ionic liquid-gated
  Ca3Ru2O7 surface

abstract:
  We report the fabrication and measurements of ionic liquid gated Hall bar
devices prepared on thin Ca$_3$Ru$_2$O$_7$ flakes exfoliated from bulk single
crystals that were grown by a floating zone method. Two types of devices with
their electrical transport properties dominated by $c$-axis transport in Type A
or that of the in-plane in Type B devices, were prepared. Bulk physical
phenomena, including a magnetic transition near 56 K, a structural and
metal-insulator transition at a slightly lower temperature, as well as the
emergence of a highly unusual metallic state as the temperature is further
lowered, were found in both types of devices. However, the Shubnikov-de Haas
oscillations were found in Type A but not Type B devices, most likely due to
enhanced disorder on the flake surface. Finally, the ionic liquid gating of a
Type B device revealed a shift in critical temperature of the structural and
metal-insulator transitions, suggesting that such transitions can be tuned by
the electric field effect.


title: The thermal Sunyaev Zel'dovich effect power spectrum in light of Planck

abstract:
  (Abridged) The amplitude of the thermal Sunyaev Zel'dovich effect (tSZ) power
spectrum is extremely sensitive to the abundance of galaxy clusters and
therefore to fundamental cosmological parameters that control their growth,
such as sigma_8 and Omega_m. Here we explore the sensitivity of the tSZ power
spectrum to important non-gravitational ('sub-grid') physics by employing the
cosmo-OWLS suite of large-volume cosmological hydrodynamical simulations, run
in both the Planck and WMAP7 best-fit cosmologies. On intermediate and small
angular scales (ell > ~1000, or theta < ~10 arcmin), accessible with the South
Pole Telescope and the Atacama Cosmology Telescope, the predicted tSZ power
spectrum is highly model dependent, with AGN feedback having a particularly
large effect. However, at large scales, observable with the Planck telescope,
the effects of sub-grid physics are minor. Comparing the simulations with
observations, we find a significant amplitude offset on all measured angular
scales (including large scales), if the Planck best-fit cosmology is assumed by
the simulations. This is shown to be a generic result for all current tSZ
models. By contrast, if the WMAP7 cosmology is adopted, there is full
consistency with the Planck power spectrum measurements on large scales and
agreement at the 2 sigma level with the SPT/ACT measurements at intermediate
scales for our fiducial AGN model, which Le Brun et al. (2014) have shown
reproduces the 'resolved' properties of the local cluster population remarkably
well. These findings strongly suggest that there are significantly fewer
massive galaxy clusters than expected for the Planck best-fit cosmology, which
is consistent with recent measurements of the tSZ number counts. Our findings
therefore pose a significant challenge to the cosmological parameter values
preferred (and/or the model adopted) by the Planck primary CMB analyses.


title:
Raman quantum memory based on an ensemble of nitrogen-vacancy centers
  coupled to a microcavity

abstract:
  We propose a scheme to realize optical quantum memories in an ensemble of
nitrogen-vacancy centers in diamond that are coupled to a micro-cavity. The
scheme is based on off-resonant Raman coupling, which allows one to circumvent
optical inhomogeneous broadening and store optical photons in the electronic
spin coherence. This approach promises a storage time of order one second and a
time-bandwidth product of order 10$^7$. We include all possible optical
transitions in a 9-level configuration, numerically evaluate the efficiencies
and discuss the requirements for achieving high efficiency and fidelity.


title:
Strongly magnetized iron white dwarfs and the total lepton number
  violation

abstract:
  The influence of a neutrinoless electron to positron conversion on a cooling
of strongly magnetized iron white dwarfs is studied.


title: Infinite Chiral Symmetry in Four Dimensions

abstract:
  We describe a new correspondence between four-dimensional conformal field
theories with extended supersymmetry and two-dimensional chiral algebras. The
meromorphic correlators of the chiral algebra compute correlators in a
protected sector of the four-dimensional theory. Infinite chiral symmetry has
far-reaching consequences for the spectral data, correlation functions, and
central charges of any four-dimensional theory with ${\mathcal N}=2$
superconformal symmetry.


title: Min Flow Rate Maximization for Software Defined Radio Access Networks

abstract:
  We consider a heterogeneous network (HetNet) of base stations (BSs) connected
via a backhaul network of routers and wired/wireless links with limited
capacity. The optimal provision of such networks requires proper resource
allocation across the radio access links in conjunction with appropriate
traffic engineering within the backhaul network. In this paper we propose an
efficient algorithm for joint resource allocation across the wireless links and
the flow control within the backhaul network. The proposed algorithm, which
maximizes the minimum rate among all the users and/or flows, is based on a
decomposition approach that leverages both the Alternating Direction Method of
Multipliers (ADMM) and the weighted-MMSE (WMMSE) algorithm. We show that this
algorithm is easily parallelizable and converges globally to a stationary
solution of the joint optimization problem. The proposed algorithm can also be
extended to deal with per-flow quality of service constraint, or to networks
with multi-antenna nodes.


title:
Epitaxial Co-Deposition Growth of CaGe2 Films by Molecular Beam Epitaxy
  for Large Area Germanane

abstract:
  Two-dimensional crystals are an important class of materials for novel
physics, chemistry, and engineering. Germanane (GeH), the germanium-based
analogue of graphane (CH), is of particular interest due to its direct band gap
and spin-orbit coupling. Here, we report the successful co-deposition growth of
CaGe2 films on Ge(111) substrates by molecular beam epitaxy (MBE) and their
subsequent conversion to germanane by immersion in hydrochloric acid. We find
that the growth of CaGe2 occurs within an adsorption-limited growth regime,
which ensures stoichiometry of the film. We utilize in situ reflection high
energy electron diffraction (RHEED) to explore the growth temperature window
and find the best RHEED patterns at 750 {\deg}C. Finally, the CaGe2 films are
immersed in hydrochloric acid to convert the films to germanane. Auger electron
spectroscopy of the resulting film indicates the removal of Ca and RHEED
patterns indicate a single-crystal film with in-plane orientation dictated by
the underlying Ge(111) substrate. X-ray diffraction and Raman spectroscopy
indicate that the resulting films are indeed germanane. Ex situ atomic force
microscopy (AFM) shows that the grain size of the germanane is on the order of
a few micrometers, being primarily limited by terraces induced by the miscut of
the Ge substrate. Thus, optimization of the substrate could lead to the
long-term goal of large area germanane films.


title:
Cosmic star formation probed via parametric stack-fitting of known
  sources to radio imaging

abstract:
  The promise of multi-wavelength astronomy has been tempered by the large
disparity in sensitivity and resolution between different wavelength regimes.
Here we present a statistical approach which attempts to overcome this by
fitting parametric models directly to image data. Specifically, we fit a model
for the radio luminosity function (LF) of star-forming galaxies to pixel
intensity distributions at 1.4 GHz coincident with near-IR selected sources in
COSMOS. Taking a mass-limited sample in redshift bins across the range $0<z<4$
we are able to fit the radio LF with ~0.2 dex precision in the key parameters
(e.g. Phi*,L*). Good agreement is seen between our results and those using
standard methods at radio and other wavelengths. Integrating our luminosity
functions to get the star formation rate density we find that galaxies with a
stellar mass greater than $10^{9.5}\,$M$_{\odot}$ contribute at least 50 per
cent of cosmic star formation at since $z=4$. The scalability of our approach
is empirically estimated, with the precision in LF parameter estimates found to
scale with the number of sources in the stack as $\sqrt{N}$. This type of
approach will be invaluable in the multi-wavelength analysis of upcoming
surveys with the SKA pathfinder facilities; LOFAR, ASKAP and MeerKAT.