• #### Double-Trace Deformations and Entanglement Entropy in AdS

We compute the bulk entanglement entropy of a massive scalar field in a Poincare AdS with the Dirichlet and Neumann boundary condition when we trace out a half space. Moreover, by taking into account the quantum back reaction to the minimal surface area, we calculate how much the entanglement entropy changes under a double-trace deformation of a holographic CFT. In the AdS3/CFT2 setup, our result agrees with the known result in 2d CFTs. In higher dimensions, our results offer holographic predictions.
Entanglement entropyScalar fieldMinimal surfaceDirichlet boundary conditionNeumann boundary conditionPartition functionMassive scalar fieldCentral chargeEntropyGreen's function...
• #### Astronomical Surveys and Big Data

Recent all-sky and large-area astronomical surveys and their catalogued data over the whole range of electromagnetic spectrum are reviewed, from Gamma-ray to radio, such as Fermi-GLAST and INTEGRAL in Gamma-ray, ROSAT, XMM and Chandra in X-ray, GALEX in UV, SDSS and several POSS I and II based catalogues (APM, MAPS, USNO, GSC) in optical range, 2MASS in NIR, WISE and AKARI IRC in MIR, IRAS and AKARI FIS in FIR, NVSS and FIRST in radio and many others, as well as most important surveys giving optical images (DSS I and II, SDSS, etc.), proper motions (Tycho, USNO, Gaia), variability (GCVS, NSVS, ASAS, Catalina, Pan-STARRS) and spectroscopic data (FBS, SBS, Case, HQS, HES, SDSS, CALIFA, GAMA). An overall understanding of the coverage along the whole wavelength range and comparisons between various surveys are given: galaxy redshift surveys, QSO/AGN, radio, Galactic structure, and Dark Energy surveys. Astronomy has entered the Big Data era. Astrophysical Virtual Observatories and Computational Astrophysics play an important role in using and analysis of big data for new discoveries.
Astronomical surveyBig dataProper motionIRASMilky WaySloan Digital Sky SurveyPhotometryVirtual observatoryWide-field Infrared Survey ExplorerStar...
• #### Modeling Lyman-\alpha\ Forest Cross-Correlations with LyMAS

We use the Ly-$\alpha$ Mass Association Scheme (LyMAS; Peirani et al. 2014) to predict cross-correlations at z = 2.5 between dark matter halos and transmitted flux in the Ly-$\alpha$ forest, and we compare these predictions to cross-correlations measured for quasars and damped Ly-$\alpha$ systems (DLAs) from the Baryon Oscillation Spectroscopic Survey (BOSS) by Font-Ribera et al. (2012, 2013). We calibrate and test LyMAS using Horizon-AGN hydrodynamical cosmological simulations of a $(100\ h^{-1}\ \rm{Mpc})^3$ comoving volume with and without AGN feedback. We apply this calibration to a $(1\ h^{-1}\ \rm{Gpc})^3$ simulation realized with $2048^3$ dark matter particles for our primary predictions. In the $100\ h^{-1}\ \rm{Mpc}$ box, LyMAS reproduces the halo-flux correlations computed from the full hydrodynamic gas distribution essentially perfectly. In the $1\ h^{-1}\ \rm{Gpc}$ box, the amplitude of the cross-correlation tracks the halo bias as expected, and the correlation for a halo sample with a distribution of masses scales linearly with the number-weighted mean bias. We provide empirical fitting functions that describe our numerical results. In the transverse separation bins used for the BOSS analyses, LyMAS cross-correlation predictions follow linear theory accurately down to small scales, though the quadrupole departs from linear theory on scales below $\sim15\ h^{-1}\ \rm{Mpc}$. Fitting the BOSS measurements requires inclusion of random velocity errors; we find best-fit RMS velocity errors of 399 km/s and 252 km/s for quasars and DLAs, respectively. We infer bias-weighted mean halo masses of $M_h/10^{12}\ h^{-1}\ M_\odot = 2.19^{+0.16}_{-0.15}$ and $0.69^{+0.16}_{-0.14}$ for the host halos of quasars and DLAs, with ~ 0.2 dex systematic uncertainty associated with redshift evolution, IGM parameters, and selection of data fitting range.
Cross-correlationVirial massQuasarDamped Lyman-alpha systemBaryon Oscillation Spectroscopic SurveyDark matterCalibrationAutocorrelationAGN feedbackLine of sight...
• #### Effects of simulated cosmological magnetic fields on the galaxy populationver. 2

We investigate the effects of varying the intensity of the primordial magnetic seed field on the global properties of the galaxy population in ideal magnetohydrodynamic cosmological simulations performed with the moving-mesh code AREPO. We vary the seed field in our calculations in a range of values still compatible with the current cosmological upper limits. We show that above a critical intensity of $\simeq 10^{-9}\,{\rm G}$, the additional pressure arising from the field strongly affects the evolution of gaseous structures, leading to a suppression of the cosmic star formation history, \rev{which is stronger for larger seed fields. This directly reflects into a lower total galaxy count above a fixed stellar mass threshold at all redshifts, and} a lower galaxy number density at fixed stellar mass and a less massive stellar component at fixed virial mass at all mass scales. These signatures may be used, in addition to the existing methods, to derive tighter constraints on primordial magnetic seed field intensities.
IntensityGalaxyCosmological magnetic fieldMagnetismVirial massCosmologyStar formationStellar massMagnetohydrodynamicsStar...
• #### A novel scenario for the possible X-ray line feature at ~3.5 keV: Charge exchange with bare sulfur ions

Motivated by recent claims of a compelling ~3.5 keV emission line from nearby galaxies and galaxy clusters, we investigate a novel plasma model incorporating a charge exchange component obtained from theoretical scattering calculations. Fitting this kind of component with a standard thermal model yields positive residuals around 3.5 keV, produced mostly by S XVI transitions from principal quantum numbers n > 8 to the ground. Such high-n states can only be populated by the charge exchange process. In this scenario, the observed 3.5 keV line flux in clusters can be naturally explained by an interaction in an effective volume of ~1 kpc^3 between a ~3 keV temperature plasma and cold dense clouds moving at a few hundred km/s. The S XVI lines at ~3.5 keV also provide a unique diagnostic of the charge exchange phenomenon in hot cosmic plasmas.
ThermalisationKeV lineIntra-cluster mediumIonizationSolar Wind Charge ExchangeCluster of galaxiesDense cloudsPerseus galaxy clusterSolar windSolar abundances...
• #### Dipole Moment Dark Matter at the LHCver. 2

Monojet and monophoton final states with large missing transverse energy (${\not E}_T$) are important for dark matter (DM) searches at colliders. We present analytic expressions for the differential cross sections for the parton-level processes, $q\bar{q}(qg)\to g(q)\chi\bar{\chi}$ and $q\bar{q}\to \gamma\chi\bar{\chi}$, for a neutral DM particle with a magnetic dipole moment (MDM) or an electric dipole moment (EDM). We collectively call such DM candidates dipole moment dark matter (DMDM). We also provide monojet cross sections for scalar, vector and axial-vector interactions. We then use ATLAS/CMS monojet${+\not E}_T$ data and CMS monophoton$+{\not E}_T$ data to constrain DMDM. We find that 7 TeV LHC bounds on the MDM DM-proton scattering cross section are about six orders of magnitude weaker than on the conventional spin-independent cross section.
Dark matterMagnetic dipole momentElectric dipole momentCMS experimentSpin-independent cross sectionPartonDirac fermionLaboratory dark matter searchPhase spaceDegree of freedom...
• #### Introduction to Chiral Perturbation Theory

This article provides a pedagogical introduction to the basic concepts of chiral perturbation theory and is designed as a text for a two-semester course on that topic. Chapter 1 serves as a general introduction to the empirical and theoretical foundations which led to the development of chiral perturbation theory. Chapter 2 deals with QCD and its global symmetries in the chiral limit; the concept of Green functions and Ward identities reflecting the underlying chiral symmetry is elaborated. In Chap. 3 the idea of a spontaneous breakdown of a global symmetry is discussed and its consequences in terms of the Goldstone theorem are demonstrated. Chapter 4 deals with mesonic chiral perturbation theory and the principles entering the construction of the chiral Lagrangian are outlined. Various examples with increasing chiral orders and complexity are given. Finally, in Chap. 5 the methods are extended to include the interaction between Goldstone bosons and baryons in the single-baryon sector, with the main emphasis put on the heavy-baryon formulation. At the end, the method of infrared regularization in the relativistic framework is discussed.
Quantum chromodynamicsGoldstone bosonChiralityGreen's functionQuark massEffective LagrangianChiral perturbation theoryPionPseudoscalarChiral limit...
• #### Extra U(1), effective operators, anomalies and dark matterver. 2

A general analysis is performed on the dimension-six operators mixing an almost hidden Z' to the Standard Model (SM), when the Z' communicates with the SM via heavy mediators. These are fermions charged under both Z' and the SM, while all SM fermions are neutral under Z'. We classify the operators as a function of the gauge anomalies behaviour of mediators and explicitly compute the dimension-six operators coupling Z' to gluons, generated at one-loop by chiral but anomaly-free, sets of fermion mediators. We prove that only one operator contribute to the couplings between Z' charged matter and on-shell gluons. We then make a complete phenomenological analysis of the scenario where the lightest fermion charged under Z' is the dark matter candidate. Combining results from WMAP/PLANCK data, mono-jet searches at LHC, and direct/indirect dark matter detections restrict considerably the allowed parameter space.
Standard ModelDark matterAxionHeavy fermionGauge invarianceBosonizationFERMI telescopeRelic abundanceDark matter candidateUnitary gauge...
• #### Landau-Yang Theorem and Decays of a Z' Boson into Two Z Bosonsver. 2

We study the decay of a Z' boson into two Z bosons by extending the Landau-Yang theorem to a parent particle decaying into two Z bosons. For a spin-1 parent the theorem predicts: 1) there are only two possible couplings and 2) the normalized differential cross-section depends on kinematics only through a phase shift in the azimuthal angle between the two decay planes of the Z boson. When the parent is a Z' the two possible couplings are anomaly-induced and CP-violating, respectively. At the Large Hadron Collider (LHC) effects of the two couplings could be disentangled when both Z bosons decay leptonically.
BosonizationZ bosonAzimuthCP violationKinematicsStandard ModelLarge Hadron ColliderDifferential cross sectionZ' bosonHelicity...
• #### The Mass Function of an X-Ray Flux-Limited Sample of Galaxy Clusters

A new X-ray selected and X-ray flux-limited galaxy cluster sample is presented. Based on the ROSAT All-Sky Survey the 63 brightest clusters with galactic latitude |bII| >= 20 deg and flux fx(0.1-2.4 keV) >= 2 * 10^{-11} ergs/s/cm^2 have been compiled. Gravitational masses have been determined utilizing intracluster gas density profiles, derived mainly from ROSAT PSPC pointed observations, and gas temperatures, as published mainly from ASCA observations, assuming hydrostatic equilibrium. This sample and an extended sample of 106 galaxy clusters is used to establish the X-ray luminosity--gravitational mass relation. From the complete sample the galaxy cluster mass function is determined and used to constrain the mean cosmic matter density and the amplitude of mass fluctuations. Comparison to Press--Schechter type model mass functions in the framework of Cold Dark Matter cosmological models and a Harrison--Zeldovich initial density fluctuation spectrum yields the constraints OmegaM = 0.12^{+0.06}_{-0.04} and sigma8 = 0.96^{+0.15}_{-0.12} (90% c.l.). Various possible systematic uncertainties are quantified. Adding all identified systematic uncertainties to the statistical uncertainty in a worst case fashion results in an upper limit OmegaM < 0.31. For comparison to previous results a relation sigma8 = 0.43 OmegaM^{-0.38} is derived. The mass function is integrated to show that the contribution of mass bound within virialized cluster regions to the total matter density is small, i.e., OmegaCluster = 0.012^{+0.003}_{-0.004} for cluster masses larger than 6.4^{+0.7}_{-0.6} * 10^{13} h_{50}^{-1} Msun.
Mass functionCluster of galaxiesStatisticsX-ray luminosityLuminosityCluster samplingFlux limited sampleCosmological modelGalaxyStatistical error...
• #### Galaxy Zoo 2: detailed morphological classifications for 304,122 galaxies from the Sloan Digital Sky Surveyver. 2

We present the data release for Galaxy Zoo 2 (GZ2), a citizen science project with more than 16 million morphological classifications of 304,122 galaxies drawn from the Sloan Digital Sky Survey. Morphology is a powerful probe for quantifying a galaxy's dynamical history; however, automatic classifications of morphology (either by computer analysis of images or by using other physical parameters as proxies) still have drawbacks when compared to visual inspection. The large number of images available in current surveys makes visual inspection of each galaxy impractical for individual astronomers. GZ2 uses classifications from volunteer citizen scientists to measure morphologies for all galaxies in the DR7 Legacy survey with m_r>17, in addition to deeper images from SDSS Stripe 82. While the original Galaxy Zoo project identified galaxies as early-types, late-types, or mergers, GZ2 measures finer morphological features. These include bars, bulges, and the shapes of edge-on disks, as well as quantifying the relative strengths of galactic bulges and spiral arms. This paper presents the full public data release for the project, including measures of accuracy and bias. The majority (>90%) of GZ2 classifications agree with those made by professional astronomers, especially for morphological T-types, strong bars, and arm curvature. Both the raw and reduced data products can be obtained in electronic format at http://data.galaxyzoo.org .
GalaxyClassificationSloan Digital Sky SurveyStripe phasesEllipticitySpiral armDisk galaxyGalaxy ZooElliptical galaxyRing galaxy...
• #### A comparison of the performance and scalability of relational and document-based web-systems for large scale applications in a rehabilitation context

Background: The Virtual Rehabilitation Environment (VRE) provides patients of long term neurological conditions with a platform to review their previous physiotherapy sessions, as well as see their goals and any treatments or exercises that their clinician has set for them to practice before their next session. Objective: The initial application implemented 21 of the 27 core features using the Microsoft ASP.NET MVC stack. However, the two core, non-functional requirements were negated from the project due to lack of experience and strict time constraints. This project aimed to investigate whether the application would be more suited to a non-relational solution. Method: The application was re-written using the MEAN stack (MongoDB, ExpressJS, AngularJS, NodeJS), an open source, fully JavaScript stack and then performance tests were carried out to compare the two applications. A scalability review was also conducted to assess the benefits and drawbacks of each technology in this aspect. Results: The investigation proved that the non-relational solution was much more efficient and performed faster. However, the choice of database was only a small part of the increase in efficiency and it was an all-round better design that gave the new application its performance upper hand. Conclusion: A proposal for a new application design is given that follows the microservice architecture used by companies such as Amazon and Netflix. The application is to be split up into four parts; database, client application, server application and content delivery network. These four, independently scalable and manageable services offer the greatest flexibility for future development at the low costs necessary for a start-up.
ArchitectureContent delivery network
• #### Single Page Application and Canvas Drawing

Recently, with the impact of AJAX a new way of web development techniques have been emerged. Hence, with the help of this model, single-page web application was introduced which can be updated/replaced independently. Today we have a new challenge of building a powerful single-page application using the currently emerged technologies. Gaining an understanding of navigational model and user interface structure of the source application is the first step to successfully build a single- page application. In this paper, it explores not only building powerful single-page application but also Two Dimensional (2D) drawings on images and videos. Moreover, in this research it clearly express the findings on 2D multi-points polygon drawing concepts on client side; real-time data binding in between drawing module on image, video and view pages.
User InterfaceNavigability of network
• #### Exponential Natural Particle Filter

Particle Filter algorithm (PF) suffers from some problems such as the loss of particle diversity, the need for large number of particles, and the costly selection of the importance density functions. In this paper, a novel Exponential Natural Particle Filter (xNPF) is introduced to solve the above problems. In this approach, a state transitional probability with the use of natural gradient learning is proposed which balances exploration and exploitation more robustly. The results show that xNPF converges much closer to the true target states than the other state of the art particle filter.
Particle filterParticlesAlgorithmsProbability...
• #### Edge physics in two-dimensional topological insulators

Topology in condensed matter physics manifests itself in the emergence of edge or surface states protected by underlying symmetries. We review two-dimensional topological insulators whose one-dimensional edge states are characterized by spin-momentum locking and protected by time-reversal symmetry. We focus in particular on their transport properties in the presence of electron interactions, which can allow the onset of different backscattering mechanisms, thus leading to deviations from the quantized conductance observed in the ballistic regime. The combined presence of helicity and electron interactions creates a new paradigm of the one-dimensional world called helical Luttinger liquid, whose theoretical properties and experimental observations are reviewed.
Edge excitationsHelicityTime-reversal symmetryTranslational invarianceBackscatteringKramers theoremSpin Quantum Hall EffectInsulatorsQuantizationQuantum point contact...
• #### The sparkling Universe: a scenario for cosmic void motions

We perform a statistical study of the global motion of cosmic voids using both a numerical simulation and observational data. We analyse their relation to large--scale mass flows and the physical effects that drive those motions. We analyse the bulk motions of voids, defined by the mean velocity of haloes in the surrounding shells in the numerical simulation, and by galaxies in the Sloan Digital Sky Survey Data Release 7. We find void mean bulk velocities close to 400 km/s, comparable to those of haloes (~ 500-600 km/s), depending on void size and the large--scale environment. Statistically, small voids move faster than large ones, and voids in relatively higher density environments have higher bulk velocities than those placed in large underdense regions. Also, we analyze the mean mass density around voids finding, as expected, large--scale overdensities (underdensities) along (opposite to) the void motion direction, suggesting that void motions respond to a pull--push mechanism. This contrasts with massive cluster motions who are mainly governed by the pull of the large-scale overdense regions. Our analysis of void pairwise velocities shows how their relative motions are generated by large--scale density fluctuations. In agreement with linear theory, voids embedded in low (high) density regions mutually recede (attract) each other, providing the general mechanism to understand the bimodal behavior of void motions. In order to compare the theoretical results and the observations we have inferred void motions in the SDSS using linear theory, finding that the estimated observational void motions are in statisticalagreement with the results of the simulation. Regarding large--scale flows, our results suggest a scenario of galaxies and galaxy systems flowing away from void centers with the additional, and morerelevant, contribution of the void bulk motion to the total velocity.
VoidSloan Digital Sky SurveyStatisticsNumerical simulationPeculiar velocityCosmologyMean mass densityClassificationDark matter haloMassive cluster...
• #### Cosmology with Superluminous Supernovae

We predict cosmological constraints for forthcoming surveys using Superluminous Supernovae (SLSNe) as standardisable candles. Due to their high peak luminosity, these events can be observed to high redshift (z~3), opening up new possibilities to probe the Universe in the deceleration epoch. We describe our methodology for creating mock Hubble diagrams for the Dark Energy Survey (DES), the "Search Using DECam for Superluminous Supernovae" (SUDSS) and a sample of SLSNe possible from the Large Synoptic Survey Telescope (LSST), exploring a range of standardisation values for SLSNe. We include uncertainties due to gravitational lensing and marginalise over possible uncertainties in the magnitude scale of the observations (e.g. uncertain absolute peak magnitude, calibration errors). We find that the addition of only ~100 SLSNe from SUDSS to 3800 Type Ia Supernovae (SNe Ia) from DES can improve the constraints on w and Omega_m by at least 20% (assuming a flat wCDM universe). Moreover, the combination of DES SNe Ia and 10,000 LSST-like SLSNe can measure Omega_m and w to 2% and 4% respectively. The real power of SLSNe becomes evident when we consider possible temporal variations in w(a), giving possible uncertainties of only 2%, 5% and 14% on Omega_m, w_0 and w_a respectively, from the combination of DES SNe Ia, LSST-like SLSNe and Planck. These errors are competitive with predicted Euclid constraints, indicating a future role for SLSNe for probing the high redshift Universe.
The Dark Energy SurveySupernovaSupernova Type IaSuper-luminous supernovaCosmologyLarge Synoptic Survey TelescopeHubble diagramCold dark matterCosmological parametersLight curve...
• #### Mapping dark matter in the Milky Way, a synopsis

Mapping the dark matter distribution across our Galaxy represents a central challenge for the near future as a new generation of space-borne and ground-based astronomical surveys swiftly comes online. Here we present a synopsis of the present status of the field, reviewing briefly the baryonic content and the kinematics of the Milky Way and outlining the methods used to infer the dark matter component. The discussion then proceeds with some of the latest developments based on our own work. In particular, we present a new compilation of kinematic measurements tracing the rotation curve of the Galaxy and an exhaustive array of observation-based baryonic models setting the contribution of stellar bulge, stellar disc and gas to the total gravitational potential. The discrepancy between these two components is then quantified to derive the latest constraints on the dark matter distribution and on modified Newtonian dynamics. We shall end with an overview of future directions to improve our mapping of the dark matter distribution in the Milky Way.
Milky WayDark matterKinematicsDark Matter Density ProfileRotation CurveStarLocal dark matter densityGalactic CenterModified Newtonian DynamicsSolar neighborhood...
• #### The Galaxy Cluster Concentration-Mass Scaling Relationver. 2

Scaling relations of clusters have made them particularly important cosmological probes of structure formation. In this work, we present a comprehensive study of the relation between two profile observables, concentration ($\mathrm{c_{vir}}$) and mass ($\mathrm{M_{vir}}$). We have collected the largest known sample of measurements from the literature which make use of one or more of the following reconstruction techniques: Weak gravitational lensing (WL), strong gravitational lensing (SL), Weak+Strong Lensing (WL+SL), the Caustic Method (CM), Line-of-sight Velocity Dispersion (LOSVD), and X-ray. We find that the concentration-mass (c-M) relation is highly variable depending upon the reconstruction technique used. We also find concentrations derived from dark matter only simulations (at approximately $\mathrm{M_{vir} \sim 10^{14} M_{\odot}}$) to be inconsistent with the WL and WL+SL relations at the $\mathrm{1\sigma}$ level, even after the projection of triaxial halos is taken into account. However, to fully determine consistency between simulations and observations, a volume-limited sample of clusters is required, as selection effects become increasingly more important in answering this. Interestingly, we also find evidence for a steeper WL+SL relation as compared to WL alone, a result which could perhaps be caused by the varying shape of cluster isodensities, though most likely reflects differences in selection effects caused by these two techniques. Lastly, we compare concentration and mass measurements of individual clusters made using more than one technique, highlighting the magnitude of the potential bias which could exist in such observational samples.
Weak lensingStrong gravitational lensingConcentration-mass relationCosmologyLine of sightPhase space causticLine-of-sight Velocity DispersionScaling lawCluster of galaxiesNavarro-Frenk-White profile...
• #### The pi0, eta, eta' -> gamma gamma*(Q^2) Decay Rates and Radiiver. 2

The low $Q^2$ slopes of the the transition form factors provide a unique method to measure the sizes of the neutral pseudo-scalar mesons, since they do not have electromagnetic form factors. From the slope one obtains the "axial transition RMS radius" $R_{PS,A} = \sqrt{<r^2>}$ for each PS meson. The present status of theory and experiment for these quantities are presented. A comparison of the $R_{PS,A}$ is presented along with the electromagnetic and scalar radii of the $\pi^{\pm}$ mesons and the proton. We observe the striking similarity of the values of axial transition radii of all of the pseudoscalar mesons to each other and to the charge radius of the $\pi^{\pm}$. In the $Q^2$ = 0 limit the transition form factor is a measure of the pseudo-scalar meson radiative width (lifetime) and is a possible fourth (unexploited) method to perform such a measurement. The $\pi^{0} \rightarrow \gamma \gamma$ decay rate is a test of QCD at the confinement scale. There is a firm QCD prediction with a theoretical uncertainty of $\simeq$ 1 \% which calls for an experimental test at the same level of accuracy. There are three methods that have been utilized to perform this measurement and the present status of the experimental tests are outlined. The current accuracy is significantly less than the theoretical uncertainty. The efforts to improve this are briefly summarized.
Form factorDecay ratePseudoscalar mesonCharge radiusIsospinPionElectromagnetic form factorQuark massLattice calculationsPrimakoff effect...
• #### Physics Opportunities of a 100 TeV Proton-Proton Collider

The discovery of the Higgs boson at the LHC exposes some of the most profound mysteries fundamental physics has encountered in decades, opening the door to the next phase of experimental exploration. More than ever, this will necessitate new machines to push us deeper into the energy frontier. In this article, we discuss the physics motivation and present the physics potential of a proton-proton collider running at an energy significantly beyond that of the LHC and a luminosity comparable to that of the LHC. 100 TeV is used as a benchmark of the center of mass energy, with integrated luminosities from 3 inverse ab to 30 inverse ab.
Large Hadron ColliderStandard ModelLuminosityDark matterHiggs bosonPartonHiggsinoTop quarkGluinoNeutralino...
• #### Proton $\beta% decay in large magnetic fields A delicate interplay between the anomalous magnetic moments of the proton and neutron makes, in magnetic fields$B\ge 2\times 10^{14}$T, the neutron stable and for fields$B\ge 5\times 10^{14}$T the proton becomes unstable to a decay into a neutron via$\beta$emission. Limits on the field strengths for which these arguments hold are presented and are related to questions of vacuum stability in the presence of such fields. Possible astrophysical consequences are discussed. • #### Primordial Magnetic Fields, Right Electrons, and the Abelian Anomalyver. 2 In the standard model there are charges with abelian anomaly only (e.g. right-handed electron number) which are effectively conserved in the early universe until some time shortly before the electroweak scale. A state at finite chemical potential of such a charge, possibly arising due to asymmetries produced at the GUT scale, is unstable to the generation of hypercharge magnetic field. Quite large magnetic fields ($\sim 10^{22}$gauss at$T\sim 100$GeV with typical inhomogeneity scale$ \sim \frac{ 10^6}{T}$) can be generated. These fields may be of cosmological interest, potentially acting as seeds for amplification to larger scale magnetic fields through non-linear mechanisms. Previously derived bounds on exotic$B-L$violating operators may also be evaded. Electroweak scaleAbelian anomalyHyperchargeGrand unification theoryHypermagnetic fieldInstabilityCosmological magnetic fieldStandard ModelHyperfieldChern-Simons number... • #### Virtual On-demand Test Lab using Cloud based Architecture Over a past few decades, VM's or Virtual machines have sort of gained a lot of momentum, especially for large scale enterprises where the need for resource optimization & power save is humongous, without compromising with performance or quality. They are a perfect environment to experiment with new applications/technologies in a completely secure and closed environment. This paper discusses how the VM technology can be leveraged to solve day to day requirement of an odd hundreds or thousands of people, organization-wide, with new computational resources using a cluster of heterogeneous low or high-end machines, independent of underlying OS, thereby maximizing resource utilization. It takes into account both opensource (like VirtualBox) & other proprietary technologies (like VMWare Workstations) available till date to propose a viable solution using cloud computing concept. The ease of scalability to multiple folds for optimizing performance & catering to an even larger set are some of the salient features of this approach. Using the snapshot feature, the state of any VM instance could be saved & served back again on request. Now, this implementation is also served by VMWare ESX server but again it's a costly solution & requires dedicated high-end machines to work with. SecurityMomentum • #### Optimizing Infrastructures for Testing Using Virtualization Virtualization technology and cloud computing have brought a paradigm shift in the way we utilize, deploy and manage computer resources. They allow fast deployment of multiple operating system as containers on physical ma- chines which can be either discarded after use or check- pointed for later re-deployment. At European Organization for Nuclear Research (CERN), we have been using virtualization technology to quickly setup virtual machines for our developers with preconfigured software to enable them to quickly test/deploy a new version of a software patch for a given application. This paper reports both on the techniques that have been used to setup a private cloud on a commodity hardware and also presents the optimization techniques we used to remove deployment specific performance bottlenecks. CERNData centerNetworksTeams... • #### Recommended Practices for Spreadsheet Testing This paper presents the authors recommended practices for spreadsheet testing. Documented spreadsheet error rates are unacceptable in corporations today. Although improvements are needed throughout the systems development life cycle, credible improvement programs must include comprehensive testing. Several forms of testing are possible, but logic inspection is recommended for module testing. Logic inspection appears to be feasible for spreadsheet developers to do, and logic inspection appears to be safe and effective. • #### Improving the Technical Aspects of Software Testing in Enterprises Many software developments projects fail due to quality problems. Software testing enables the creation of high quality software products. Since it is a cumbersome and expensive task, and often hard to manage, both its technical background and its organizational implementation have to be well founded. We worked with regional companies that develop software in order to learn about their distinct weaknesses and strengths with regard to testing. Analyzing and comparing the strengths, we derived best practices. In this paper we explain the project's background and sketch the design science research methodology used. We then introduce a graphical categorization framework that helps companies in judging the applicability of recommendations. Eventually, we present details on five recommendations for tech-nical aspects of testing. For each recommendation we give im-plementation advice based on the categorization framework. • #### Study Paper on Test Case generation for GUI Based Testing With the advent of WWW and outburst in technology and software development, testing the software became a major concern. Due to the importance of the testing phase in a software development life cycle, testing has been divided into graphical user interface (GUI) based testing, logical testing, integration testing, etc.GUI Testing has become very important as it provides more sophisticated way to interact with the software. The complexity of testing GUI increased over time. The testing needs to be performed in a way that it provides effectiveness, efficiency, increased fault detection rate and good path coverage. To cover all use cases and to provide testing for all possible (success/failure) scenarios the length of the test sequence is considered important. Intent of this paper is to study some techniques used for test case generation and process for various GUI based software applications. • #### Prediction in complex systems: the case of the international trade network Predicting the future evolution of complex systems is one of the main challenges in complexity science. Based on a current snapshot of a network, link prediction algorithms aim to predict its future evolution. We apply here link prediction algorithms to data on the international trade between countries. This data can be represented as a complex network where links connect countries with the products that they export. Link prediction techniques based on heat and mass diffusion processes are employed to obtain predictions for products exported in the future. These baseline predictions are improved using a recent metric of country fitness and product similarity. The overall best results are achieved with a newly developed metric of product similarity which takes advantage of causality in the network evolution. CausalityHybridizationLink predictionBipartite networkComplex systemsMass diffusivityInternational trade networkComplex networkPreferential attachmentOptimization... • #### Searching the Internet for evidence of time travelers Time travel has captured the public imagination for much of the past century, but little has been done to actually search for time travelers. Here, three implementations of Internet searches for time travelers are described, all seeking a prescient mention of information not previously available. The first search covered prescient content placed on the Internet, highlighted by a comprehensive search for specific terms in tweets on Twitter. The second search examined prescient inquiries submitted to a search engine, highlighted by a comprehensive search for specific search terms submitted to a popular astronomy web site. The third search involved a request for a direct Internet communication, either by email or tweet, pre-dating to the time of the inquiry. Given practical verifiability concerns, only time travelers from the future were investigated. No time travelers were discovered. Although these negative results do not disprove time travel, given the great reach of the Internet, this search is perhaps the most comprehensive to date. Time travelTwitterCommunication • #### Structural Dissection for Controlling Complex Networks Controlling complex networked systems has been a central goal in different fields and understanding controllability of complex networks has been at the forefront of contemporary science. Despite the recent progress in the development of controllability theories for complex networks, we continue to lack efficient tools to fully understand the effect of network topology and interaction strengths among nodes on controllability. Here we establish a framework to discern the significance of links and nodes for controlling general complex networks in a simple way based on local information. A dissection process is offered by the framework to probe and classify nodes and links completely, giving rise to a criterion for strong structural controllability. Analytical results indicate phase transitions associated with link and node categories, and strong structural controllability. Applying the tools to real networks demonstrate that real technological networks are strong structurally controllable, whereas most of real social and biological networks are not. Moreover, real networks are flexible to be controlled because of many options of driver nodes, and real directed and undirected networks shows essential difference with respect node classification. Complex networkOptimizationPhase transitionsClassificationDirected networkScale-freeHomogenizationSelf-organizationDegree distributionRank... • #### Theory of the Structural Glass Transition: A Pedagogical Review The random first-order transition (RFOT) theory of the structural glass transition is reviewed in a pedagogical fashion. The rigidity that emerges in crystals and glassy liquids is of the same fundamental origin. In both cases, it corresponds with a breaking of the translational symmetry; analogies with freezing transitions in spin systems can also be made. The common aspect of these seemingly distinct phenomena is a spontaneous emergence of the molecular field, a venerable and well-understood concept. In crucial distinction from periodic crystallisation, the free energy landscape of a glassy liquid is vastly degenerate, which gives rise to new length and time scales while rendering the emergence of rigidity gradual. We obviate the standard notion that to be mechanically stable a structure must be essentially unique; instead, we show that bulk degeneracy is perfectly allowed but should not exceed a certain value. The present microscopic description thus explains both crystallisation and the emergence of the landscape regime followed by vitrification in a unified, thermodynamics-rooted fashion. The article contains a self-contained exposition of the basics of the classical density functional theory and liquid theory, which are subsequently used to quantitatively estimate, without using adjustable parameters, the key attributes of glassy liquids, viz., the relaxation barriers, glass transition temperature, and cooperativity size. These results are then used to quantitatively discuss many diverse glassy phenomena, including: the intrinsic connection between the excess liquid entropy and relaxation rates, the non-Arrhenius temperature dependence of$\alpha$-relaxation, the dynamic heterogeneity, ... (see Comments for the remainder of Abstract.) LiquidsEntropyGlassGlass transitionVibrationRelaxationMean fieldMeltingElasticityQuenching... • #### Dark matter searches with Cherenkov telescopes: nearby dwarf galaxies or local galaxy clusters?ver. 3 In this paper, we compare dwarf galaxies and galaxy clusters in order to elucidate which object class is the best target for gamma-ray DM searches with imaging atmospheric Cherenkov telescopes (IACTs). We have built a mixed dwarfs+clusters sample containing some of the most promising nearby dwarf galaxies (Draco, Ursa Minor, Wilman 1 and Segue 1) and local galaxy clusters (Perseus, Coma, Ophiuchus, Virgo, Fornax, NGC5813 and NGC5846), and then compute their DM annihilation flux profiles by making use of the latest modeling of their DM density profiles. We also include in our calculations the effect of DM substructure. Willman 1 appears as the best candidate in the sample. However, its mass modeling is still rather uncertain, so probably other candidates with less uncertainties and quite similar fluxes, namely Ursa Minor and Segue 1, might be better options. As for galaxy clusters, Virgo represents the one with the highest flux. However, its large spatial extension can be a serious handicap for IACT observations and posterior data analysis. Yet, other local galaxy cluster candidates with more moderate emission regions, such as Perseus, may represent good alternatives. After comparing dwarfs and clusters, we found that the former exhibit annihilation flux profiles that, at the center, are roughly one order of magnitude higher than those of clusters, although galaxy clusters can yield similar, or even higher, integrated fluxes for the whole object once substructure is taken into account. Even when any of these objects are strictly point-like according to the properties of their annihilation signals, we conclude that dwarf galaxies are best suited for observational strategies based on the search of point-like sources, while galaxy clusters represent best targets for analyses that can deal with rather extended emissions. Finally, we study the detection prospects for IACTs [ABRIDGED] Cluster of galaxiesDark matter annihilationCherenkov telescopeA dwarfsDwarf galaxyPerseus galaxy clusterPoint spread functionDark Matter Density ProfileNeutralinoDraco Dwarf Spheroidal galaxy... • #### Field Theoretic Description of Ultrarelativistic Electron-Positron Plasmasver. 2 Ultrarelativistic electron-positron plasmas can be produced in high-intensity laser fields and play a role in various astrophysical situations. Their properties can be calculated using QED at finite temperature. Here we will use perturbative QED at finite temperature for calculating various important properties, such as the equation of state, dispersion relations of collective plasma modes of photons and electrons, Debye screening, damping rates, mean free paths, collision times, transport coefficients, and particle production rates, of ultrarelativistic electron-positron plasmas. In particular, we will focus on electron-positron plasmas produced with ultra-strong lasers. Electron-positron plasmaQuark-gluon plasmaLasersQuantum electrodynamicsUltrarelativistic electron-positron plasmasHard thermal loopPositronThermalisationMean free pathQuantum chromodynamics... • #### Satellite galaxies in semi-analytic models of galaxy formation with sterile neutrino dark matter The sterile neutrino is a viable dark matter candidate that can be produced in the early Universe via non-equilibrium processes, and would therefore possess a highly non-thermal spectrum of primordial velocities. In this paper we analyse the process of structure formation with this class of dark matter particles. To this end we construct primordial dark matter power spectra as a function of the lepton asymmetry,$L_6$, that is present in the primordial plasma and leads to resonant sterile neutrino production. We compare these power spectra with those of thermally produced dark matter particles and show that resonantly produced sterile neutrinos are much colder than their thermal relic counterparts. We also demonstrate that the shape of these power spectra are not determined by the free-streaming scale alone. We then use the power spectra as an input for semi-analytic models of galaxy formation in order to predict the number of luminous satellite galaxies in a Milky Way-like halo. By assuming that the mass of the Milky Way halo must be no more than$2\times10^{12}M_{\odot}$(the adopted upper bound based on current astronomical observations) we are able to constrain the value of$L_6$for$M_{s}\le 5$keV. We also show that the range of$L_6$that is in best agreement with the 3.5keV line (if produced by decays of 7keV sterile neutrino) requires that the Milky Way halo has a mass no smaller than$1.2\times10^{12}M_{\odot}$. Finally, we compare the power spectra obtained by direct integration of the Boltzmann equations for a non-resonantly produced sterile neutrino with the fitting formula of Viel et al. and find that the latter significantly underestimates the power amplitude on scales relevant to satellite galaxies. Sterile neutrinoThermalisationLepton asymmetrySatellite galaxySterile neutrino massDark matter candidateFree streaming of particlesMatter power spectrumSemi-analytical model of galaxy formationWarm dark matter... • #### A Chandra Study of Radial Temperature Profiles of the Intra-Cluster Medium in 50 Galaxy Clusters In order to investigate the spatial distribution of the ICM temperature in galaxy clusters in a quantitative way and probe the physics behind, we analyze the X-ray spectra of a sample of 50 galaxy clusters, which were observed with the Chandra ACIS instrument in the past 15 years, and measure the radial temperature profiles out to$0.45r_{500}$. We construct a physical model that takes into account the effects of gravitational heating, thermal history (such as radiative cooling, AGN feedback, and thermal conduction) and work done via gas compression, and use it to fit the observed temperature profiles by running Bayesian regressions. The results show that in all cases our model provides an acceptable fit at the 68% confidence level. To further validate this model we select nine clusters that have been observed with both Chandra (out to$\gtrsim 0.3r_{500}$) and Suzaku (out to$\gtrsim 1.5r_{500}$), fit their Chandra spectra with our model, and compare the extrapolation of the best-fits with the Suzaku measurements. We find that the model profiles agree with the Suzaku results very well in seven clusters. In the rest two clusters the difference between the model and observation is possibly caused by local thermal substructures. Our study also implies that for most of the clusters the assumption of hydrostatic equilibrium is safe out to at least$0.5r_{500}$, and the non-gravitational interactions between dark matter and its luminous counterpart is consistent with zero. Temperature profileThermalisationCluster of galaxiesChandra X-ray ObservatoryHydrostatic equilibriumRadiative coolingCompressibilityDark matterThermal conductivityAGN feedback... • #### Parameter splitting in dark energy: is dark energy the same in the background and in the cosmic structures? We perform an empirical consistency test of General Relativity/dark energy by disentangling expansion history and growth of structure constraints. We replace each late-universe parameter that describes the behavior of dark energy with two meta-parameters: one describing geometrical information in cosmological probes, and the other controlling the growth of structure. If the underlying model (a standard wCDM cosmology with General Relativity) is correct, that is under the null hypothesis, the two meta-parameters coincide. If they do not, it could indicate a failure of the model or systematics in the data. We present a global analysis using state-of-the-art cosmological data sets which points in the direction that cosmic structures prefer a weaker growth than that inferred by background probes. This result could signify inconsistencies of the model, the necessity of extensions to it or the presence of systematic errors in the data. We examine all these possibilities. The fact that the result is mostly driven by a specific sub-set of galaxy clusters abundance data, points to the need of a better understanding of this probe. Planck missionDark energyAbundanceCosmologyCosmic microwave backgroundBaryon acoustic oscillationsNull hypothesisSupernova Type IaLambda-CDM modelDensity parameter... • #### Cluster-Void Degeneracy Breaking: Dark Energy, Planck and the Largest Cluster & Void Combining galaxy cluster and void abundances breaks the degeneracy between mean matter density$\Omega_{\rm m}$and power spectrum normalization$\sigma_8$. In a first for voids, we constrain$\Omega_{\rm m} = 0.21 \pm 0.10$and$\sigma_8 = 0.95 \pm 0.21$for a flat$\Lambda$CDM universe, using extreme-value statistics on the claimed largest cluster and void. The Planck-consistent results detect dark energy with two objects, independently of other dark energy probes. Cluster-void studies also offer complementarity in scale, density, and non-linearity - of particular interest for testing modified-gravity models. VoidAbundanceDark energyCosmologyDensity contrastStatisticsCMB cold spotComplementarityNeutrinoDark matter... • #### The matter distribution in the local universe as derived from galaxy groups in SDSS DR12 and 2MRSver. 2 Context. Friends-of-friends algorithms are a common tool to detect galaxy groups and clusters in large survey data. For them to be as precise as possible, they have to be carefully calibrated using mock-catalogues. Aims. To create an accurate and robust description of the matter distribution in the local universe using the most up-to-date available data. This will provide input for a specific cosmological test planned as follow-up to this work, and will be useful for general extra- galactic and cosmological research. Methods. We create a set of galaxy group catalogues based on the 2MRS and SDSS DR12 catalogues using a friends-of-friends based group finder algorithm. The algorithm is carefully calibrated and optimised on a new set of wide-angle mock catalogues from the Millennium simulation, such as to provide accurate total mass estimates of the galaxy groups taking into account the relevant observational biases in 2MRS and SDSS. Results. We provide four different catalogues: 1) a 2MRS based group catalogue; 2) a SDSS DR12 based group catalogue reaching out to a redshift of 0.11; 3) a catalogue providing additional fundamental plane distances for all groups of the SDSS catalogue that host elliptical galaxies; 4) a catalogue of the mass distribution in the local universe based on a combination of our 2MRS and SDSS catalogues. The latter catalogue is especially designed for a specific cosmological test planned as follow-up to this work. Conclusions. While motivated by a specific cosmological test, three of the four catalogues that we produced are well suited to act as reference databases for a variety of extragalactic and cosmological science cases. Our catalogue of fundamental plane distances for SDSS groups provides further added value to this paper. Sloan Digital Sky SurveyTwo Micron All-Sky Redshift SurveyFriends of friends algorithmCosmologyCalibrationMillennium RunLuminosity functionMalmquist biasLocal UniverseAbsolute magnitude... • #### Sodium Absorption Systems towards SN Ia 2014J Originate on Interstellar Scales Na I D absorbing systems towards Type Ia Supernovae (SNe Ia) have been intensively studied over the last decade with the aim of finding circumstellar material (CSM), which is an indirect probe of the progenitor system. However, it is difficult to deconvolve CSM components from non-variable, and often dominant, components created by interstellar material (ISM). We present a series of high resolution spectra of SN Ia 2014J from before maximum brightness to >~250 days after maximum brightness. The late-time spectrum provides unique information for determining the origin of the Na I D absorption systems. The deep late-time observation allows us to probe the environment around the SN at a large scale, extending to >~40 pc. We find that a spectrum of diffuse light in the vicinity, but not directly in the line-of-sight of the SN, has absorbing systems nearly identical to those obtained for the `pure' SN line-of-sight. Therefore, basically all Na I D systems seen towards SN 2014J must originate from foreground material that extends to at least ~40 pc in projection and none at the CSM scale. A fluctuation in the column densities at a scale of ~20 pc is also identified. After subtracting the diffuse, "background" spectrum, the late-time SN line-of-sight Na I D profile is consistent with that of near-maximum brightness profiles. The lack of variability on a ~1 year timescale is consistent with the ISM interpretation for the gas. AbsorbanceSN 2014JAbsorptivitySupernova Type IaLine of sightInterstellar mediumNatriumMessier 82SupernovaExtinction... • #### Identification of the ~3.55 keV emission line candidate objects across the sky Emission line at the energy ~3.55 keV detected in different galaxies and galaxy clusters has caused a lot of discussion in high-energy astrophysics and particle physics communities. To reveal the origin of the line, we analyzed publicly available observations of MOS cameras from XMM-Newton cosmic observatory - the instrument with the largest sensitivity for narrow faint X-ray lines - previously combined in X-ray sky maps. Because of extremely large timescale needed for detailed analysis, we used the wavelet method instead. Extensive simulations of the central part of Andromeda galaxy are used to check the validity of this method. The resulting list of wavelet detections now contains 235 sky regions. This list will be used in future works for more detailed spectral analysis. WaveletKeV lineAndromeda galaxyCluster of galaxiesSpectral analysisXMM-Newton MOS cameraHigh energy astronomyObservatoriesLocal significanceDark matter... • #### Re-Evaluation of the Elastic Scattering of Supersymmetric Dark Matter We examine the cross sections for the elastic scattering of neutralinos$\chi$on nucleons$p,n$, as functions of$m_\chi$in the constrained minimal supersymmetric standard model. We find narrow bands of possible values of the cross section, that are considerably lower than some previous estimates. The constrained model is based on the minimal supergravity-inspired framework for the MSSM, with universal scalar and gaugino masses$m_0, m_{1/2}$, and$\mu$and the MSSM Higgs masses treated as dependent parameters. We explore systematically the region of the$(m_{1/2}, m_0)$plane where LEP and other accelerator constraints are respected, and the relic neutralino density lies in the range$0.1 \le \Omega_{\chi} h^2 \le 0.3$preferred by cosmology. We update previous discussions of both the spin-independent and -dependent scattering matrix elements on protons and neutrons, using recent analyses of low-energy hadron experiments. Minimal supersymmetric Standard ModelElastic scatteringNeutralinoCosmologyLightest Supersymmetric ParticleDark matterGauginoSpin independentSoft supersymmetry breakingConstrained Minimal Supersymmetric Standard Model... • #### Indirect search for dark matter with micrOMEGAs2.4ver. 2 We present a new module of micrOMEGAs devoted to the computation of indirect signals from dark matter annihilation in any new model with a stable weakly interacting particle. The code provides the mass spectrum, cross-sections, relic density and exotic fluxes of gamma rays, positrons and antiprotons. The propagation of charged particles in the Galactic halo is handled with a new module that allows to easily modify the propagation parameters. PositronDark matterDark matter annihilationAntiprotonCharged particlePYTHIAMinimal supersymmetric Standard ModelEarthGalaxyDark matter halo... • #### An information theoretic approach to Sidorenko's conjecturever. 3 We investigate the famous conjecture by Erd\H os-Simonovits and Sidorenko using information theory. Our method gives a unified treatment for all known cases of the conjecture and it implies various new results as well. Our topological type conditions allow us to extend Sidorenko's conjecture to large families of$k$-uniform hypergraphs. This is somewhat unexpected since the conjecture fails for$k\$ uniform hypergraphs in general.
Information theoryTopology
• #### New axes for the fundamental planever. 2

We argue that the stellar velocity dispersion observed in an elliptical galaxy is a good proxy for the halo velocity dispersion. As dark matter halos are almost completely characterized by a single scale parameter, the stellar velocity dispersion tells us the virial radius of the halo and the mass contained within. This permits non-dimensionalizing of the stellar mass and effective radius axes of the stellar mass fundamental plane by the virial radius and halo mass, respectively.
Stellar velocity dispersionVelocity dispersionStellar massDark matter haloStarVirial radiusElliptical galaxyDark matterDissipationEllipticity...
• #### A critical assessment of the metal content of the ICM

Our goal is to provide a robust estimate of the metal content of the ICM in massive clusters. We make use of published abundance profiles for a sample of ~60 nearby systems, we include in our estimate uncertainties associated to the measurement process and to the almost total lack of measures in cluster outskirts. We perform a first, albeit rough, census of metals finding that the mean abundance of the ICM within r_180 is very poorly constrained, 0.06Z_sol < Z < 0.26Z_sol, and presents no tension with expectations. Similarly, the question of if and how the bulk of the metal content in clusters varies with cosmic time, is very much an open one. A solid estimate of abundances in cluster outskirts could be achieved by combining observations of the two experiments which will operate on board Athena, the XIFU and the WFI, provided they do not fall victim to the de-scoping process that has afflicted several space observatories over the last decade.
Intra-cluster mediumAbundanceMetallicityEntropyOutskirt of a galaxy clusterSystematic errorAbundance profileMassive clusterStatisticsEquivalent width...