• #### Warm Dark Matter: The End is Nighver. 2

Over the last decade warm dark matter (WDM) has been repeatedly proposed as an alternative scenario to the standard cold dark matter (CDM) one, potentially resolving several disagreements between the CDM model and observations on small scales. Here we reconsider the most important CDM small scale discrepancies in the light of recent observational constraints on WDM. As a result, we find that a conventional thermal (or thermal-like) WDM cosmology with a particle mass in agreement with Lyman-$\alpha$ is nearly indistinguishable from CDM on the relevant scales and therefore fails to alleviate any of the small scale problems. The reason for this failure is that the power spectrum of conventional WDM falls off too rapidly. To maintain WDM as a significantly different alternative to CDM, more evolved production mechanisms leading to multiple dark matter components and a gradually decreasing small scale power spectrum have to be considered.
Warm dark matterCold dark matterDwarf galaxyDark matterStructure formationVelocity Width FunctionVelocity functionCircular velocityParticle massCosmology...
• #### Higgs Physics

These lectures review the background to Higgs physics, its current status following the discovery of a/the Higgs boson at the LHC, models of Higgs physics beyond the Standard Model and prospects for Higgs studies in future runs of the LHC and at possible future colliders.
Standard ModelHiggs bosonSymmetrySupersymmetryBosonizationScalar fieldBeyond the Standard ModelRenormalizationVector bosonQuark...
• #### Exploring Multi-Modal Distributions with Nested Sampling

In performing a Bayesian analysis, two difficult problems often emerge. First, in estimating the parameters of some model for the data, the resulting posterior distribution may be multi-modal or exhibit pronounced (curving) degeneracies. Secondly, in selecting between a set of competing models, calculation of the Bayesian evidence for each model is computationally expensive using existing methods such as thermodynamic integration. Nested Sampling is a Monte Carlo method targeted at the efficient calculation of the evidence, but also produces posterior inferences as a by-product and therefore provides means to carry out parameter estimation as well as model selection. The main challenge in implementing Nested Sampling is to sample from a constrained probability distribution. One possible solution to this problem is provided by the Galilean Monte Carlo (GMC) algorithm. We show results of applying Nested Sampling with GMC to some problems which have proven very difficult for standard Markov Chain Monte Carlo (MCMC) and down-hill methods, due to the presence of large number of local minima and/or pronounced (curving) degeneracies between the parameters. We also discuss the use of Nested Sampling with GMC in Bayesian object detection problems, which are inherently multi-modal and require the evaluation of Bayesian evidence for distinguishing between true and spurious detections.
Monte Carlo Markov chainBayesian evidenceMonte Carlo methodBayesian approachBayesian posterior probabilityNested sampling algorithmBayesianQuadratureBayes' theoremBayesian Model Selection...
• #### Random tensor models in the large N limit: Uncoloring the colored tensor models

Tensor models generalize random matrix models in yielding a theory of dynamical triangulations in arbitrary dimensions. Colored tensor models have been shown to admit a 1/N expansion and a continuum limit accessible analytically. In this paper we prove that these results extend to the most general tensor model for a single generic, i.e. non-symmetric, complex tensor. Colors appear in this setting as a canonical book-keeping device and not as a fundamental feature. In the large N limit, we exhibit a set of Virasoro constraints satisfied by the free energy and an infinite family of multicritical behaviors with entropy exponents \gamma_m=1-1/m.
Random matrixRiemann surfaceEntropyPerturbative expansionGraph1/N expansionTensorActionFree energyLanguage...
• #### The microscopic dynamics of quantum space as a group field theory

We provide a rather extended introduction to the group field theory approach to quantum gravity, and the main ideas behind it. We present in some detail the GFT quantization of 3d Riemannian gravity, and discuss briefly the current status of the 4-dimensional extensions of this construction. We also briefly report on recent results obtained in this approach and related open issues, concerning both the mathematical definition of GFT models, and possible avenues towards extracting interesting physics from them.
Quantum gravityQuantizationSpin foamLoop quantum gravitySpin networkField theoryFeynman diagramsSymmetryQuantum field theoryManifold...
• #### Ten questions on Group Field Theory (and their tentative answers)

We provide a short and non-technical summary of our current knowledge and some possible perspectives on the group field theory formalism for quantum gravity, in the form of a (partial) FAQ (with answers). Some of the questions and answers relate to aspects of the formalism that concern loop quantum gravity. This summary also aims at giving a brief, rough guide to the recent literature on group field theory (and tensor models).
Field theoryQuantum gravityLoop quantum gravityTensor...
• #### Towards a relativistic transport theory of nuclear matter

Transport theoryRenormalizationNuclear matterPerturbation theorySchwinger-Dyson equationMean-field approximation...
• #### Magnetic fields in Accretion Discs around Neutron Stars - Consequences for the change of spin

Accretion disks are ubiquitous in the universe and it is generally accepted that magnetic fields play a pivotal role in accretion-disk physics. The spin history of millisecond pulsars, which are usually classified as magnetized neutron stars spun up by an accretion disk, depends sensitively on the magnetic field structure, and yet highly idealized models from the 80s are still being used for calculating the magnetic field components. We present a possible way of improving the currently used models with a semi-analytic approach. The resulting magnetic field profile of both the poloidal and the toroidal component can be very different from the one suggested previously. This might dramatically change our picture of which parts of the disk tend to spin the star up or down.
Neutron starAccretion diskStarAccretionViscosityMillisecond pulsarTurbulenceMean fieldTurbulent diffusionVariable star period change...
• #### On the quantum correction for thermodynamic equilibrium

Thermodynamics
• #### Tight bonds between sterile neutrinos and dark matter

Despite the astonishing success of standard $\Lambda$CDM cosmology, there is mounting evidence for a tension with observations at small and intermediate scales. We introduce a simple model where both cold dark matter (DM) and sterile neutrinos are charged under a new $U(1)_X$ gauge interaction. The resulting DM self-interactions resolve the tension with the observed abundances and internal density structures of dwarf galaxies. At the same time, the sterile neutrinos can account for both the small hot DM component favored by cosmological observations and the neutrino anomalies found in short-baseline experiments.
Sterile neutrinoCold dark matterCosmologyHot dark matterStandard ModelDark matterNeutrino experiment anomalyNeutrinoDwarf galaxyMilky Way...
• #### Potential of LOFT telescope for the search of dark matter

Large Observatory For X-ray Timing (LOFT) is a next generation X-ray telescope selected by European Space Agency as one of the space mission concepts within the Cosmic Vision'' programme. The Large Area Detector on board of LOFT will be a collimator-type telescope with an unprecedentedly large collecting area of about 10 square meters in the energy band between 2 and 100 keV. We demonstrate that LOFT will be a powerful dark matter detector, suitable for the search of the X-ray line emission expected from decays of light dark matter particles in galactic halos. We show that LOFT will have sensitivity for dark matter line search more than an order of magnitude higher than that of all existing X-ray telescopes. In this way, LOFT will be able to provide a new insight into the fundamental problem of the nature of dark matter.
Dark matterLOFTLarge Area Detector onboard LOFT satelliteField of viewDark matter decayTelescopesDecaying dark matterCluster of galaxiesDM particlesCosmic X-ray background...
• #### Particle dark matter searches in the anisotropic sky

Anisotropies in the electromagnetic emission produced by dark matter annihilation or decay in the extragalactic sky are a recent tool in the quest for a particle dark matter evidence. We review the formalism to compute the two-point angular power spectrum in the halo-model approach and discuss the features and the relative size of the various auto- and cross-correlation signals that can be envisaged for anisotropy studies. From the side of particle dark matter signals, we consider the full multi-wavelength spectrum, from the radio emission to X-ray and gamma-ray productions. We discuss the angular power spectra of the auto-correlation of each of these signals and of the cross-correlation between any pair of them. We then extend the search to comprise specific gravitational tracers of dark matter distribution in the Universe: weak-lensing cosmic shear, large-scale-structure matter distribution and CMB-lensing. We have shown that cross-correlating a multi-wavelength dark matter signal (which is a direct manifestation of its particle physics nature) with a gravitational tracer (which is a manifestation of the presence of large amounts of unseen matter in the Universe) may offer a promising tool to demonstrate that what we call dark matter is indeed formed by elementary particles.
Cross-correlationAutocorrelationLarge scale structureDecaying dark matterGalaxyIntensityCmb lensingCosmic shearAngular power spectrumTwo-point correlation function...
• #### On the coset duals of extended higher spin theories

We study the holographic duality between the M x M matrix extension of Vasiliev higher spin theories on AdS3 and the large N limit of SU(N+M)/SU(N) x U(1) type cosets. We present a simplified proof for the agreement of the spectra and clarify the relation between this duality and the version in which the cosets are replaced by Kazama-Suzuki models of Grassmannian type.
CosetPartition functionDualityGauge fieldSupersymmetryPoisson bracketFundamental representationSymmetryEigenvalueRegularization...
• #### Manifest causality in quantum field theory with sources and detectors

We introduce a way to compute scattering amplitudes in quantum field theory including the effects of particle production and detection via classical source functions. Our amplitudes are manifestly causal, by which we mean that the source and detector are always linked by a connected chain of retarded propagators. We show how the amplitudes can be derived from a path integral in the Schwinger-Keldysh "in-in" formalism. Focussing on phi-cubed theory, we reproduce the expected results at tree-level. Our approach differs from the standard S-matrix approach because the particle sources allow both positive and negative energy flow forwards in time.
Retarded propagatorGraphCausalityExpectation ValueScattering amplitudeSelf-energyQuantum field theoryS-matrixG2Symmetry...
• #### Inflation after Planck: and the winners are

We review the constraints that the recently released Cosmic Microwave Background (CMB) Planck data put on inflation and we argue that single field slow-roll inflationary scenarios (with minimal kinetic term) are favored. Then, within this class of models, by means of Bayesian inference, we show how one can rank the scenarios according to their performances, leading to the identification of the best models of inflation''.
Planck missionSlow rollCosmic microwave backgroundModel of inflationSlow roll parametersStatisticsBayesian evidenceBayesianLikelihood functionWavefunction...
• #### Acceleration of raindrops formation due to tangling-clustering instability in turbulent stratified atmosphere

Condensation of water vapor on active cloud condensation nuclei produces micron-size water droplets. To form rain, they must grow rapidly into at least 50-100 micron-size droplets. Observations show that this process takes only 15-20 minutes. The unexplained physical mechanism of such fast growth, is crucial for understanding and modeling of rain, and known as "condensation-coalescence bottleneck in rain formation". We show that the recently discovered phenomenon of the tangling clustering instability of small droplets in temperature-stratified turbulence (Phys. Fluids 25, 085104, 2013) results in the formation of droplet clusters with drastically increased droplet number densities and strong five-orders-of-magnitude enhancement of the collision-coalescence rate inside the clusters. The mechanism of tangling clustering instability in the temperature-stratified turbulence is much more effective than the previously considered pure inertial clustering caused by the centrifugal effect of turbulent vortices. Our analysis of the droplet growth explains the observed fast growth of cloud droplets from the initial 1 micron-size droplets to 40-50 micron-size droplets within 15-20 minutes.
TurbulenceInstabilityEvaporationCondensationWater vaporRelative humidityRapidityEddyVorticitySupersaturation...
• #### Fundamentals of the Exact Renormalization Groupver. 4

Various aspects of the Exact Renormalization Group (ERG) are explored, starting with a review of the concepts underpinning the framework and the circumstances under which it is expected to be useful. A particular emphasis is placed on the intuitive picture provided for both renormalization in quantum field theory and universality associated with second order phase transitions. A qualitative discussion of triviality, asymptotic freedom and asymptotic safety is presented. Focusing on scalar field theory, the construction of assorted flow equations is considered using a general approach, whereby different ERGs follow from field redefinitions. It is recalled that Polchinski's equation can be cast as a heat equation, which provides intuition and computational techniques for what follows. The analysis of properties of exact solutions to flow equations includes a proof that the spectrum of the anomalous dimension at critical fixed-points is quantized. Two alternative methods for computing the beta-function in lambda phi^4 theory are considered. For one of these it is found that all explicit dependence on the non-universal differences between a family of ERGs cancels out, exactly. The Wilson-Fisher fixed-point is rediscovered in a rather novel way. The discussion of nonperturbative approximation schemes focuses on the derivative expansion, and includes a refinement of the arguments that, at the lowest order in this approximation, a function can be constructed which decreases monotonically along the flow. A new perspective is provided on the relationship between the renormalizability of the Wilsonian effective action and of correlation functions, following which the construction of manifestly gauge invariant ERGs is sketched, and some new insights are given. Drawing these strands together suggests a new approach to quantum field theory.
Two-point correlation functionEffective actionGaussian fixed pointRenormalization groupPropagatorQuantum field theoryPerturbation theoryRenormalizationScalar field theoryDegree of freedom...
• #### An elementary proof of the non-renormalization theorem for the Wess-Zumino modelver. 2

Using the exact renormalization group (ERG) differential equation, we give an elementary proof of the non-renormalization theorem for the Wess-Zumino model. We introduce auxiliary fields to linearize the supersymmetry transformation, but we do not rely on the superfield techniques. We give sufficient background material on the Wilson action and the ERG formalism to make the paper self-contained.
R-symmetrySupersymmetryRenormalizationChiralityAuxiliary fieldSuperfieldWess-Zumino modelAnomalous dimensionSuperpotentialEuler beta function...
• #### On the Renormalization of Theories of a Scalar Chiral Superfieldver. 3

An exact renormalization group for theories of a scalar chiral superfield is formulated, directly in four dimensional Euclidean space. By constructing a projector which isolates the superpotential from the full Wilsonian effective action, it is shown that the nonperturbative nonrenormalization theorem follows, quite simply, from the flow equation. Next, it is argued that there do not exist any physically acceptable non-trivial fixed points. Finally, the Wess-Zumino model is considered, as a low energy effective theory. Following an evaluation of the one and two loop beta-function coefficients, to illustrate the ease of use of the formalism, it is shown that the beta-function in the massless case does not receive any nonperturbative power corrections.
SuperpotentialRenormalizationAnomalous dimensionSuperspaceWess-Zumino modelEffective actionScalar field theoryChiral superfieldRegularizationPerturbation theory...
• #### Goldstone Bosons as Fractional Cosmic Neutrinos

It is suggested that Goldstone bosons may be masquerading as fractional cosmic neutrinos, contributing about 0.39 to what is reported as the effective number of neutrino types in the era before recombination. The broken symmetry associated with these Goldstone bosons is further speculated to be the conservation of the particles of dark matter.
Goldstone bosonStandard ModelWeakly interacting massive particleNeutrinoSymmetryDark matterBosonizationQuarkHiggs bosonWIMP annihilation...
• #### Derivation of Gauge Invariance from High-Energy Unitarity Bounds on the s Matrix

Gauge fieldUnitarityS-matrixGauge invarianceField theoryScalar field theoryFeynman diagramSpontaneous symmetry breakingRenormalizationScalar...

Gauge theory
• #### Magnetic Fields Produced by Phase Transition Bubbles in the Electroweak Phase Transition

The electroweak phase transition, if proceeding through nucleation and growth of bubbles, should generate large scale turbulent flow, which in turn generates magnetic turbulence and hence magnetic fields on the scale of turbulent flow. We discuss the seeding of this turbulent field by the motion of the dipole charge layers in the phase transition bubble walls, and estimate the strength of the produced fields.
Turbulent flowElectroweak phase transitionPhase transitionsMagnetohydrodynamic turbulenceTurbulenceTop quarkElectroweak scaleTwo-point correlation functionBaryon asymmetry of the UniverseVorticity...
• #### Baryogenesis

We will discuss different mechanisms for baryogenesis with special emphasis to those of them that can be experimentally tested.
Baryogenesis
• #### Dark matter, singlet extensions of the nuMSM, and symmetriesver. 2

We consider an extension of the nuMSM in which sterile neutrino masses originate from the VEV of a Higgs singlet phi and dark matter is produced through the decays of phi rather than through active-sterile neutrino oscillations. This model, which we refer to as the nuNMSM, can readily satisfy constraints on warm dark matter from the Lyman-alpha forest. We show that the hierarchical parameters of the nuNMSM can arise from symmetries broken at or near the Planck scale for two specific models of the scalar sector: one in which phi stabilizes the electroweak vacuum and one in which phi is the inflaton. These models have several experimental signatures that are distinct from the nuMSM, including additional dark radiation that is relativistic at both primordial nucleosynthesis and CMB decoupling and, for the former, a large invisible branching ratio of the Higgs.
SymmetryStandard ModelDark matterMajorana massPlanck scaleSterile neutrinoVacuum expectation valueBranching ratioActive neutrinoInflaton...
• #### On the minimal active-sterile neutrino mixing in seesaw type I mechanism with sterile neutrinos at GeV scale

Renewed interest in GeV-scale sterile neutrinos capable of explaining active neutrino oscillations via see-saw type I mechanism has been expressed in several proposals of direct searches. Given this activity we estimate the minimal values of sterile-active mixing angles provided one, two, or three sterile neutrinos are lighter than D-meson.
Sterile neutrinoActive neutrinoType I seesawNeutrinoYukawa couplingNeutrino oscillationsStandard ModelHadronizationNeutrino Minimal Standard ModelMixing angle...
• #### Schwinger's Approach to Einstein's Gravity, or Einstein vs. Schwinger? Not!

Julian Schwinger (1918--1994), founder of renormalized quantum electrodynamics, was arguably the leading theoretical physicist of the second half of the 20th century. Thus it is not surprising that he made contributions to gravity theory as well. His students made major impacts on the still uncompleted program of constructing a quantum theory of gravity. Schwinger himself had no doubt of the validity of general relativity, although he preferred a particle-physics viewpoint based on gravitons and the associated fields, and not the geometrical picture of curved spacetime. This note provides a brief summary of his contributions and attitudes toward the subject of gravity.
General relativityGravitonPlanetTheories of gravitySunQuantum electrodynamicsGreen's functionCosmological constantRenormalizationEinstein field equations...
• #### The zeta function for circular graphs

We study the entire function zeta(n,s) which is the sum of l to the power -s, where l runs over the positive eigenvalues of the Laplacian of the circular graph C(n) with n vertices. We prove that the roots of zeta(n,s) converge for n to infinity to the line Re(s)=1/2 in the sense that for every compact subset K in the complement of this line, and large enough n, no root of the zeta function zeta(n,s) is in K. To prove this, we look at the Dirac zeta function, which uses the positive eigenvalues of the Dirac operator D=d+d^* of the circular graph, the square root of the Laplacian. We extend a Newton-Coates-Rolle type analysis for Riemann sums and use a derivative which has similarities with the Schwarzian derivative. As the zeta functions zeta(n,s) of the circular graphs are entire functions, the result does not say anything about the roots of the classical Riemann zeta function zeta(s), which is also the Dirac zeta function for the circle. Only for Re(s)>1, the values of zeta(n,s) converge suitably scaled to zeta(s). We also give a new solution to the discrete Basel problem which is giving expressions like zeta_n(2) = (n^2-1)/12 or zeta_n(4) = (n^2-1)(n^2+11)/45 which allows to re-derive the values of the classical Basel problem zeta(2) = pi^2/6 or zeta(4)=pi^4/90 in the continuum limit.
Zeta functionGraphRiemann sumEigenvalueCritical lineRiemann zeta functionEntire functionBasel problemHurwitz zeta functionRenormalization...
• #### A New Probe of the Higgs Self-Couplingver. 2

It is shown that the Higgs associated production cross section at an $e^+ e^-$ collider is sensitive to the Higgs self-coupling, $h^3$, at next-to-leading order. A new indirect method is proposed for constraining the self-coupling below the di-Higgs production threshold at a $240$ GeV $e^+ e^-$ synchrotron. It has been estimated that the self-coupling could be constrained to an accuracy of $50\%$ at the high luminosity LHC and $83\%$ at a $500$ GeV ILC. By comparison, the method proposed here would enable this parameter to be constrained at a $240$ GeV $e^+ e^-$ synchrotron to an accuracy of $28\%$, significantly enhancing the physics potential of a collider such as the recently proposed TLEP machine. Even in theoretically realistic scenarios, where there is a degree of model dependence due to the possibility of dominant tree-level $hZZ$ coupling modifications, indirect experimental bounds on the Higgs self-coupling are possible. This is the first proposal demonstrating the sensitivity of a $240$ GeV $e^+ e^-$ synchrotron to the Higgs self-coupling and, if only the self-coupling has been modified, constitutes the most sensitive probe of variations in this coupling at current and next-generation colliders.
Higgs self-couplingNext-to-leading order computationLarge Hadron ColliderInternational Linear ColliderStandard ModelSynchrotronLuminosityHiggs bosonHiggs massRelaxation...
• #### Effective $θ$ term by CP-odd electromagnetic background fields

We discuss our study of QCD in the presence of CP-odd electromagnetic (e.m.) background fields. We investigate the propagation of the CP-odd term from the e.m. sector to the strong sector, inducing an effective $\theta$ term. We discuss the method we have used in our lattice QCD simulations, and the results of our analysis, which are relevant to the determination of the effective pseudoscalar QED-QCD interactions. We also explore how these CP-odd e.m. background fields influence the number of the Dirac zero modes in our configurations.
Topological quantum numberZero modeChiralityQuarkNumerical simulationAxial anomalyPseudoscalarCoolingQuark massGauge field...
• #### Massive sterile neutrinos as warm Dark Matterver. 3

We show that massive sterile neutrinos mixed with the ordinary ones may be produced in the early universe in the right amount to be natural warm dark matter particles. Their mass should be below 40 keV and the corresponding mixing angles sin^2 2\theta > 10^{-11} for mixing with \nu_\mu or \nu_\tau, while mixing with \nu_e is slightly stronger bounded with mass less than 30 keV.
Sterile neutrinoNeutrinoActive neutrinoWarm dark matterThe early UniverseDark matter particleCosmologyNeutrino massDark matterSupernova 1987A...
• #### CMB constraints on mass and coupling constant of light pseudoscalar particles

Transformation of the CMB photons into light pseudo-scalar particles at the post big bang nucleosynthesis epoch is considered. Using the present day value of large scale magnetic fields to estimate it at earlier cosmological epochs, we calculate the oscillation probability of the photons into light pseudo-scalar particles with an account of the coherence breaking in the cosmological plasma. Demanding that the process of the photon transformation does not lead to an exceedingly large CMB temperature anisotropy, we further constrain the coupling of axion like particles to photons, $10^{-18}\textrm{nG}\times \textrm{GeV}^{-1}\lesssim g_{\phi\gamma} B \lesssim 10^{-12}\textrm{nG}\times \textrm{GeV}^{-1}$, where $B$ is the magnitude of large scale cosmological magnetic field at present, for the axion like particle mass in the interval: $10^{-25}$ eV $\lesssim m_{\phi\gamma}\lesssim 10^6$ eV. Our results differ from the previously obtained ones since we use the density matrix method which is more accurate than the wave function approximation for the description of the oscillations with an essential coherence breaking.
Axion-like particleCosmic microwave backgroundCosmologyIndex of refractionBig bang nucleosynthesisPseudoscalarAxionIonization fractionDensity parameterIonization...
• #### How typical is the Coma cluster?

Coma is frequently used as the archetype z~0 galaxy cluster to compare higher redshift work against. It is not clear, however, how representative the Coma cluster is for galaxy clusters of its mass or X-ray luminosity, and significantly: recent works have suggested that the galaxy population of Coma may be in some ways anomolous. In this work, we present a comparison of Coma to an X-ray selected control sample of clusters. We show that although Coma is typical against the control sample in terms of its internal kinematics (substructure and velocity dispersion profile), it has a significantly high (~3sigma) X-ray temperature set against clusters of comparable mass. By de-redshifting our control sample cluster galaxies star-formation rates using a fit to the galaxy main sequence evolution at z < 0.1, we determine that the typical star-formation rate of Coma galaxies as a function of mass is higher than for galaxies in our control sample at a confidence level of > 99 per cent. One way to alleviate this discrepency and bring Coma in-line with the control sample would be to have the distance to Coma to be slightly lower, perhaps through a non-negligible peculiar velocity with respect to the Hubble expansion, but we do not regard this as likely given precision measurements using a variety of approaches. Therefore in summary, we urge caution in using Coma as a z~0 baseline cluster in galaxy evolution studies.
Cluster of galaxiesComasGalaxyStar formation rateComa ClusterSloan Digital Sky SurveyKinematicsX-ray luminosityVelocity dispersion profileVelocity dispersion...
• #### Two Loop Neutrino Model and Dark Matter Particles with Global $B-L$ Symmetryver. 2

We study a two loop induced seesaw model with global $U(1)_{B-L}$ symmetry, in which we consider two component dark matter particles. The dark matter properties are investigated together with some phenomenological constraints such as electroweak precision test, neutrino masses and mixing and lepton flavor violation. In particular, the mixing angle between the Standard Model like Higgs and an extra Higgs is extremely restricted by the direct detection experiment of dark matter. We also discuss the contribution of Goldstone boson to the effective number of neutrino species $\Delta N_{\rm eff}\approx0.39$ which has been reported by several experiments.
Dark matterSterile neutrinoNeutrino massStandard ModelSymmetryMixing angleLepton flavour violationGoldstone bosonHiggs potentialNeutrino...
• #### Revealing the influence of dark matter on the nature of motion and the families of orbits in axisymmetric galaxy models

An axially symmetric galactic gravitational model composed of a dense, massive and spherical nucleus with an additional dark matter halo component was used, to distinguish between the regular and chaotic character of orbits of stars that move in the meridional plane (R,z). We investigated two different cases: (i) a flat-disk galaxy (ii) an elliptical galaxy. It is of particular interest to reveal how the portion of the dark matter inside the main body of the galaxy influences the ordered or chaotic nature of motion. Varying the ratio of dark matter to stellar mass, we monitored the evolution not only of the percentage of chaotic orbits, but also of the percentages of orbits that compose the main regular resonant families, by classifying regular orbits into different families. Moreover we tried, to reveal how the starting position of the parent periodic orbits of each regular family changes with respect to the fractional portion of dark matter. We compared our results with previous similar work.
Dark matterGalaxyRegularizationElliptical galaxyPeriodic orbitPhase planeDisk galaxyDark matter haloChaosRotation Curve...
• #### Leptophilic dark matter in gauged $L_μ-L_τ$ extension of MSSMver. 2

Positron excess upto energies $\sim$350 GeV has been observed by AMS-02 result and it is consistent with the positron excess observed by PAMELA upto 100 GeV. There is no observed excess of anti-protons over the expected CR background. We propose a leptophilic dark matter with an $U(1)_{L_{\mu}-L_{\tau}}$ gauge extension of MSSM. The dark matter is an admixture of the $L_{\mu}-L_{\tau}$ gaugino and fermionic partners of the extra SU(2) singlet Higgs boson, which break the $L_{\mu}-L_{\tau}$ symmetry. We construct the SM$\otimes U(1)_{L_{\mu}-L_{\tau}}$ SUSY model which provides the correct relic density of dark matter and is consistent with constrain on $Z'$ from LHC. The large dark matter annihilation cross-section into $\mu^{+}\mu^{-}$ and $\tau^{+}\tau^{-}$, needed to explain PAMELA and AMS-02 is achieved by Breit-Wigner resonance.
Dark matterPositronNeutralinoAlpha Magnetic SpectrometerMinimal supersymmetric Standard ModelGauginoPAMELA experimentSymmetrySupersymmetryBoost factor...
• #### Combined Flux and Anisotropy Searches Improve Sensitivity to Gamma Rays from Dark Matter

Searches for dark matter annihilation signals in the diffuse gamma-ray background are promising. We present the first comprehensive study utilizing both flux and anisotropy, using the example of a spectral line signal. Besides improving sensitivity, a combined analysis will help separately determine the particle properties of dark matter and the cosmological aspects of its clumping into halo substructure. The significance of a signal in a shot-noise-dominated anisotropy analysis increases linearly with time $t$, as opposed to $\sqrt{t}$ for a flux analysis, so a flux hint might be confirmed with an anisotropy signal. A first combined line search with Fermi-LAT would provide powerful new sensitivity; one with the proposed GAMMA-400 would be dramatically better.
Dark matterAngular power spectrumFERMI telescopeSpectral lineDark matter annihilationGAMMA-400StatisticsGalactic haloCosmologyConfidence interval...
• #### Falsifying Leptogenesis at the LHC

We investigate the impact of observing lepton number violating (LNV) processes at the LHC on the viability of thermal leptogenesis scenarios. Measuring a non-zero value for the cross section of any LNV process would put a strong lower limit on the washout factor for the effective lepton number density in the early universe at times close to the electroweak phase transition and thus would lead to important constraints on any high-scale model for the generation of the observed baryon asymmetry based on LNV. In particular, for leptogenesis models with masses of the right-handed neutrinos heavier than the mass scale observed at the LHC, the implied large washout factors would lead to a violation of the out-of-equilibrium condition and exponentially suppress the net lepton number produced in such leptogenesis models.
Sterile neutrinoBaryon asymmetry of the UniverseLepton numberLepton asymmetryLeptogenesisPartonThe early UniverseLepton flavour violationStandard ModelBoltzmann transport equation...
• #### The mass and angular momentum distribution of simulated massive galaxies to large radiiver. 2

We study the mass distributions, circular velocity curves (CVCs), line-of-sight kinematics and angular momenta out to many Re for a sample of 42 cosmological zoom simulations of massive galaxies. In order to reduce the particle noise at large radii, we temporally smooth the observables of the simulated galaxies in a static potential. The mass of the simulated galaxies is parametrised by vcirc at r=5Re. We find: (i) The projected stellar density distributions at large radii can be well fitted by S'ersic functions. The S'ersic indices range from 3 to 13 and correlate with stellar mass and galaxy size (low n, low mass, small size). (ii) The dark matter halo density profiles are consistent with simple power-law models, corresponding to flat dark matter CVCs for lower-mass systems, and rising CVCs for high-mass halos. (iii) The massive systems have nearly flat total CVCs at large radii, while the less massive systems have mildly decreasing CVCs. The slope of the CVC at large radii correlates with S'ersic index and vcirc itself. (iv) The short axes of simulated galaxies and their host dark matter are well aligned and their short-to-long axis ratios are correlated. (v) Stellar root mean square velocity v_rms(R) profiles are slightly falling, consistent with planetary nebulae observations in the outer halos of most ETGs. There are no analogues in the simulated galaxies of the second group of ETGs with rapidly falling v_rms(R) profiles. (vi) The line-of-sight velocity fields show that rotation properties at small and large radii are correlated. Most radial profiles for the cumulative specific angular momentum parameter lambda(R) are nearly flat or slightly rising from 2Re to 5Re. (vii) Stellar mass, ellipticity at large radii eps(5Re), and lambda(5Re) are correlated:the more massive systems have less angular momentum and are rounder, as for observed ETGs. (Full abstract is in downloadable file)
GalaxyDark matterKinematicsStarEllipticityDark matter haloCircular velocityEarly-type galaxyRapidityPlanetary nebula...
• #### Higgs branch localization of 3d N=2 theoriesver. 2

We study N=2 supersymmetric gauge theories on squashed 3-sphere and S^1xS^2. Recent studies have shown that the partition functions in a class of N=2 theories have factorized representations in terms of vortex and anti-vortex partition functions by explicitly evaluating matrix integrals obtained by Coulomb branch localization. We directly derive this structure by performing Higgs branch localization. It turns out that more general N=2 theories have this factorization property. We also discuss the factorization of supersymmetric Wilson loop.
Partition functionChiralityWilson loopSupersymmetric gauge theorySupersymmetryHolomorphChern-Simons termGauge theoryQuantum mechanicsVacuum expectation value...
• #### Gravitational stability of dark energy in galaxies and clusters of galaxiesver. 3

We analyze the behavior of the scalar field as dark energy of the Universe in a static world of galaxies and clusters of galaxies. We find the analytical solutions of evolution equations of the density and velocity perturbations of dark matter and dark energy, which interact only gravitationally, along with the perturbations of metric in a static world with background Minkowski metric. Using them it was shown that quintessential and phantom dark energy in the static world of galaxies and clusters of galaxies is gravitationally stable and can only oscillate by the influence of self-gravity. In the gravitational field of dark matter perturbations it is able to condense monotonically, but the amplitude of density and velocity perturbations on all scales remains small. It was illustrated also, that the "accretion" of phantom dark energy in the region of dark matter overdensities causes formation of dark energy underdensities - the regions with negative amplitude of density perturbations of dark energy.
Dark energyGalaxyDark matterCluster of galaxiesPrimordial density perturbationScalar fieldJeans instabilityAccretionCosmologyModels of dark energy...
• #### The Schwinger pair production rate in confining theories via holography

We study the Schwinger pair production in confining theories. The production rate in an external electric field E is numerically evaluated by using the holographic description. There exist two kinds of critical values of the electric field, i) E=E_c, above which there is no potential barrier and particles are freely generated, ii) E=E_s, below which the confining string tension dominates the electric field and the pair production does not occur. We argue the universal exponents associated with the critical behaviors.
D3 branePair productionCritical valueWilson loopString tensionDeconfinementQuantum chromodynamicsGauge theoryFundamental particleSchwinger pair production...
• #### Peculiar velocities in redshift space: formalism, N-body simulations and perturbation theory

Direct measurements of peculiar velocities of galaxies and clusters of galaxies can in principle provide explicit information on the three dimensional mass distribution, but this information is modulated by the fact that velocity field is sampled at galaxy positions, and is thus probing galaxy momentum. We derive expressions for the cross power spectrum between the density and momentum field and the auto spectrum of the momentum field in redshift space, by extending the distribution function method to these statistics. The resulting momentum cross and auto power spectra in redshift space are expressed as infinite sums over velocity moment correlators in real space, as is the case for the density power spectrum in redshift space. We compare the predictions of the velocity statistics to those measured from N-body simulations for both dark matter and halos. We find that in redshift space linear theory predictions for the density-momentum cross power spectrum as well as for the momentum auto spectrum fail to predict the N-body results at very large scales. On the other hand, our nonlinear perturbation theory (PT) prediction dramatically improves the accuracy. We also present the same analysis in configuration space, computing the redshift-space pairwise mean infall velocities and velocity correlation function and compare to nonlinear PT.
Redshift spaceReal spaceStatisticsGalaxyDark matterTwo-point correlation functionPeculiar velocityLine of sightVelocity dispersionSatellite galaxy...
• #### Neutrino Physics from the Cosmic Microwave Background and Large Scale Structurever. 2

This is a report on the status and prospects of the quantification of neutrino properties through the cosmological neutrino background for the Cosmic Frontier of the Division of Particles and Fields Community Summer Study long-term planning exercise. Experiments planned and underway are prepared to study the cosmological neutrino background in detail via its influence on distance-redshift relations and the growth of structure. The program for the next decade described in this document, including upcoming spectroscopic galaxy surveys eBOSS and DESI and a new Stage-IV CMB polarization experiment CMB-S4, will achieve sigma(sum m_nu) = 16 meV and sigma(N_eff) = 0.020. Such a mass measurement will produce a high significance detection of non-zero sum m_nu, whose lower bound derived from atmospheric and solar neutrino oscillation data is about 58 meV. If neutrinos have a minimal normal mass hierarchy, this measurement will definitively rule out the inverted neutrino mass hierarchy, shedding light on one of the most puzzling aspects of the Standard Model of particle physics --- the origin of mass. This precise a measurement of N_eff will allow for high sensitivity to any light and dark degrees of freedom produced in the big bang and a precision test of the standard cosmological model prediction that N_eff = 3.046.
Cosmic microwave backgroundNeutrinoNeutrino massCluster of galaxiesLarge scale structureCosmologyCmb lensingTransition edge sensorBaryon Oscillation Spectroscopic SurveyMatter power spectrum...
• #### Mapping Dark Matter in the Gamma-Ray Sky with Galaxy Catalogs

Cross-correlating gamma-ray maps with locations of galaxies in the low-redshift Universe vastly increases sensitivity to signatures of annihilation of dark matter particles. Low-redshift galaxies are ideal targets, as the largest contribution to anisotropy in the gamma-ray sky from annihilation comes from z < 0.1, where we expect minimal contributions from astrophysical sources such as blazars. Cross-correlating the five-year data of Fermi-LAT with the redshift catalog of the 2MASS survey can detect gamma rays from annihilation if dark matter has the canonical annihilation cross section and its mass is smaller than about 100 GeV.
GalaxyTwo Micron All Sky SurveyCross-correlationFERMI telescopeBlazarDark matter annihilationDark matter subhaloDark matterRedshift surveyDM mass...
• #### Charge Quantization in the CP(1) Nonlinear Sigma-Modelver. 2

We investigate the consistency conditions for matter fields coupled to the four-dimensional (N = 1 supersymmetric) CP(1) nonlinear sigma model (the coset space SU(2)_G/U(1)_H). We find that consistency requires that the U(1)_H charge of the matter be quantized, in units of half of the U(1)_H charge of the Nambu-Goldstone (NG) boson, if the matter has a nonsingular kinetic term and the dynamics respect the full group SU(2)_G. We can then take the linearly realized group U(1)_H to comprise the weak hypercharge group U(1)_Y of the Standard Model. Thus we have charge quantization without a Grand Unified Theory (GUT), completely avoiding problems like proton decay, doublet-triplet splitting, and magnetic monopoles. We briefly investigate the phenomenological implications of this model-building framework. The NG boson is fractionally charged and completely stable. It can be naturally light, avoiding constraints while being a component of dark matter or having applications in nuclear physics. We also comment on the extension to other NLSMs on coset spaces, which will be explored more fully in a followup paper.
BosonizationCharge quantizationGrand unification theoryStandard ModelSupersymmetryNon-linear sigma modelQuantizationDark matterGoldstone bosonSymmetry...
• #### The Planck and LHC results and particle physics

I will discuss the recent LHC and Planck results, which are completely compatible with the Standard Model of particle physics, and the standard cosmological model ($\Lambda$CDM), respectively. It turns out that the extension of the Standard Model is, of course, required, but can be very minimal. I will discuss also what future measurements may be important to test this approach.
Standard ModelNon-minimal couplingHiggs inflationModel of inflationHiggs boson massDegree of freedomPlanck missionHiggs fieldE-foldingEinstein frame...
• #### Simplified Supersymmetry with Sneutrino LSPver. 2

The current searches of supersymmetry (SUSY) are based on the neutralino lightest sparticle (LSP). In this article we instead focus on SUSY with sneutrino LSP. It is well motivated in many contexts, especially in which sneutrino services as a dark matter candidate. We first develop a simplified model, which contains the stop, chagino/neutralino and sneutrino, to describe the LHC phenomenologies of a large class of models with sneutrino LSP. Then we investigate bounds on the model using the SUSY searches at the 8 TeV LHC. Strong exclusion limits are derived, e.g., masses of stop and chargino can be excluded up to about 900 GeV and 550 GeV, respectively. We also propose optimizations for some searches without turning to higher energy and luminosity.
Lightest Supersymmetric ParticleSupersymmetryCharginoDark matterPair productionNeutralinoHadronizationBranching ratioNext to lightest supersymmetric particleMinimal supersymmetric Standard Model...
• #### IceCube, DeepCore, PINGU and the indirect search for supersymmetric dark matter

The discovery of a particle that could be the lightest CP-even Higgs of the minimal supersymmetric extension of the Standard Model (MSSM) and the lack of evidence so far for supersymmetry at the LHC have many profound implications, including for the phenomenology of supersymmetric dark matter. In this study, we re-evaluate and give an update on the prospects for detecting supersymmetric neutralinos with neutrino telescopes, focussing in particular on the IceCube/DeepCore Telescope as well as on its proposed extension, PINGU. Searches for high-energy neutrinos from the Sun with IceCube probe MSSM neutralino dark matter models with the correct Higgs mass in a significant way. This is especially the case for neutralino dark matter models producing hard neutrino spectra, across a wide range of masses, while PINGU is anticipated to improve the detector sensitivity especially for models in the low neutralino mass range.
NeutralinoIceCube Neutrino ObservatoryMinimal supersymmetric Standard ModelSunDark matterNeutrinoHiggsinoNeutrino telescopeWeakly interacting massive particleNeutrino flux...
• #### Observation of the Dependence of Scintillation from Nuclear Recoils in Liquid Argon on Drift Fieldver. 3

We have exposed a dual-phase Liquid Argon Time Projection Chamber (LAr-TPC) to a low energy pulsed narrowband neutron beam, produced at the Notre Dame Institute for Structure and Nuclear Astrophysics to study the scintillation light yield of recoiling nuclei in a LAr-TPC. A liquid scintillation counter was arranged to detect and identify neutrons scattered in the LAr-TPC target and to select the energy of the recoiling nuclei. We report the observation of a significant dependence on drift field of liquid argon scintillation from nuclear recoils of 11 keV. This observation is important because, to date, estimates of the sensitivity of noble liquid TPC dark matter searches are based on the assumption that electric field has only a small effect on the light yield from nuclear recoils.
ScintillationLiquidsTime projection chamberDark matterLiquid xenonNuclear astrophysicsScintillation counterProton beamRecombinationIonization...