Using the longitudinal expression of Hubble expansion rate for the general Lemaître-Tolman-Bondi (LTB) metric as a function of cosmic time, we examine the scale on which the Copernican principle holds in the context of a void model. By way of performing parameter estimation on the constrained Garcia-Bellido–Haugbolle void model, we show that the Hubble parameter data favors a void with a characteristic radius of 2–3 Gpc. This brings the void model closer, but not yet enough, to harmony with observational indications given by the background kinetic Sunyaev-Zel’dovich effect and the normalization of near-infrared galaxy luminosity function. However, the test of such void models may ultimately lie in the future detection of the discrepancy between longitudinal and transverse expansion rates, a touchstone of inhomogeneous models. With the proliferation of observational Hubble parameter data and future large-scale structure observation, a definitive test could be performed on the question of cosmic homogeneity. Particularly, the spherical LTB void models have been ruled out, but more general nonspherical inhomogeneities still need to be tested by observation. In this paper, we utilize a spherical void model to provide guidelines into how observational tests may be done with more general models in the future.

All species of (nonconformally coupled) particles are produced during inflation so long as their mass $M$ is not too much larger than $H$, the expansion rate during inflation. It has been shown that if a particle species that is normally massive ($M\gg H$) couples to the inflaton field in such a way that its mass vanishes, or at least becomes small ($M<H$), for a particular value of the inflaton field, then not only are such particles produced, but an irruption of that particle species can occur during inflation. In this paper we analyze creation of a massive particle species during inflation in a variety of settings, paying particular attention to models which realize such an irruptive production mechanism.

We point out three correlated predictions of the axion monodromy inflation model: the large amplitude of gravitational waves, the suppression of power on horizon scales and on scales relevant for the formation of dwarf galaxies. While these predictions are likely generic to models with oscillations in the inflaton potential, the axion monodromy model naturally accommodates the required running spectral index through Planck-scale corrections to the inflaton potential. Applying this model to a combined data set of Planck, ACT, SPT, and WMAP low-$\ell$ polarization cosmic microwave background (CMB) data, we find a best-fit tensor-to-scalar ratio $r_{0.05}={0.07}_{-0.04}^{+0.05}$ due to gravitational waves, which may have been observed by the BICEP2 experiment. Despite the contribution of gravitational waves, the total power on large scales (CMB power spectrum at low multipoles) is lower than the standard $\mathrm{\Lambda }\mathrm{CDM}$ cosmology with a power-law spectrum of initial perturbations and no gravitational waves, thus mitigating some of the tension on large scales. There is also a reduction in the matter power spectrum of 20–30% at scales corresponding to $k=10{\text{Mpc}}^{-1}$, which are relevant for dwarf galaxy formation. This will alleviate some of the unsolved small-scale structure problems in the standard $\mathrm{\Lambda }\mathrm{CDM}$ cosmology. The inferred matter power spectrum is also found to be consistent with recent Lyman-$\alpha$ forest data, which is in tension with the Planck-favored $\mathrm{\Lambda }\mathrm{CDM}$ model with a power-law primordial power spectrum.

We construct the effective field theory of a perfect fluid in the early Universe. Focusing on the case where the fluid has the equation of state of radiation, we show that it may lead to corrections to the background dynamics that can dominate over those of an effective field theory of gravity alone. We describe the periods of accelerated expansion, in the form of inflationary and bounce solutions, that arise in the background dynamics and discuss their regime of validity within effective field theory.

We derive the quantum master equations for heavy quark systems in a high-temperature quark-gluon plasma in the Lindblad form. The master equations are derived in the influence functional formalism for open quantum systems in perturbation theory. These master equations have a wide range of applications, such as decoherence of a heavy quarkonium and Langevin dynamics of a heavy quark in the quark-gluon plasma. We also show the equivalence between the quarkonium master equations in the recoilless limit and the Schrödinger equations with stochastic potential.

We consider a simple addition to the minimal supersymmetric Standard Model (MSSM) of a “sister Higgs” (${\mathrm{\Sigma }}_d$), a Higgs field that participates in electroweak symmetry breaking but does not give any direct masses to Standard Model matter fields. If this new field carries charge under a new gauge group, $G_s$, the Higgs mass is naturally much larger than in the MSSM due to a next-to-minimal supersymmetric Standard Model–type interaction, but with ${\mathrm{\Sigma }}_d$ playing the role of $H_d$. The addition of the sister Higgs allows new $R$-parity violating operators ${\mathrm{\Sigma }}_d{H}_{d}E$, which are less constrained than a conventional leptonic $R$-parity violation. Unification motivates the presence of colored $G_s$-charged fields, whose production can lead to new $b$-rich final states and modifications to decays of gluinos, as well as new opportunities for $R$-parity violation. The presence of additional sister charges allows the possibilities that a lightest sister-charged particle (LSiP) could be stable, although we find the possibility of a LSiP dark matter candidate is generally very constrained.

We study SUSY signatures at the 7, 8 and 14 TeV LHC employing the 19-parameter, R-parity conserving p(henomenological)MSSM, in the scenario with a neutralino lightest supersymmetric particle (LSP). Our results were obtained via a fast Monte Carlo simulation of the ATLAS SUSY analysis suite. The flexibility of this framework allows us to study a wide variety of SUSY phenomena simultaneously and to probe for weak spots in existing SUSY search analyses. We determine the ranges of the sparticle masses that are either disfavored or allowed after the searches with the 7 and 8 TeV data sets are combined. We find that natural SUSY models with light squarks and gluinos remain viable. We extrapolate to 14 TeV with both $300{\mathrm{fb}}^{-1}$ and $3{\mathrm{ab}}^{-1}$ of integrated luminosity and determine the expected sensitivity of the $\text{jets}+\mathrm{MET}$ and stop searches to the pMSSM parameter space. We find that the high-luminosity LHC will be powerful in probing SUSY with neutralino LSPs and can provide a more definitive statement on the existence of natural supersymmetry.

We present a detailed study of the variation of shear viscosity $\eta$, with temperature and baryon chemical potential within the framework of the Polyakov–Nambu–Jona-Lasinio model. $\eta$ is found to depend strongly on the spectral width of the quasiparticles present in the model. The variation of $\eta$ across the phase diagram has distinctive features for different kinds of transitions. These variations have been used to study the possible location of the critical end point and are cross-checked with similar studies of variations of specific heat. Finally, using a parametrization of the freeze-out surface in heavy-ion collision experiments, the variation of the shear viscosity to entropy density ratio has also been discussed as a function of the center-of-mass energy of collisions.

The properties and consequences of complex saddle points are explored in phenomenological models of QCD at nonzero temperature and density. Such saddle points are a consequence of the sign problem and should be considered in both theoretical calculations and lattice simulations. Although saddle points in finite-density QCD are typically in the complex plane, they are constrained by a symmetry that simplifies analysis. We model the effective potential for Polyakov loops using two different potential terms for confinement effects and consider three different cases for quarks: very heavy quarks, massless quarks without modeling of chiral symmetry breaking effects, and light quarks with both deconfinement and chiral symmetry restoration effects included in a pair of Polyakov-Nambu-Jona Lasinio models. In all cases, we find that a single dominant complex saddle point is required for a consistent description of the model. This saddle point is generally not far from the real axis; the most easily noticed effect is a difference between the Polyakov loop expectation values $⟨{\mathrm{Tr}}_{F}P⟩$ and $⟨{\mathrm{Tr}}_F{P}^{†}⟩$, and that is confined to a small region in the $\mu -T$ plane. In all but one case, a disorder line is found in the region of critical and/or crossover behavior. The disorder line marks the boundary between exponential decay and sinusoidally modulated exponential decay of correlation functions. Disorder line effects are potentially observable in both simulation and experiment. Precision simulations of QCD in the $\mu -T$ plane have the potential to clearly discriminate between different models of confinement.

Kwiecinski, Martin, and Stasto [Phys. Rev. D 56, 3991 (1997)] argue for inclusion of DGLAP terms into BFKL evolution of unintegrated gluon density. The equation was reformulated by Oliveira, Martin, and Ryskin [Evolution in Opening Angle Combining DGLAP and BFKL Logarithms (to be published)] employing the opening angle $\theta =\frac{k}{xp}$ as the evolution variable. It leads to a description of a $\theta$-integrated gluon density. This paper is a numerical study of these two similar combined $\mathrm{BFKL}+\mathrm{DGLAP}$ formulations. It is a demonstration of feasibility of the new approach. The different ways of subtracting the contribution common for BFKL and DGLAP proposed by Kwiecinski, Martin, and Stasto [Phys. Rev. D 56, 3991 (1997)] and Oliveira, Martin, and Ryskin [Evolution in Opening Angle Combining DGLAP and BFKL Logarithms (to be published)] are compared. The numerical tests confirm that the $\theta$ variable is a more natural evolution variable for this kind of equation.

In this paper, we examine the strategies and prospects for distinguishing between traditional dark-matter models and models with nonminimal dark sectors—including models of Dynamical Dark Matter—at hadron colliders. For concreteness, we focus on events with two hadronic jets and large missing transverse energy at the Large Hadron Collider (LHC). As we discuss, simple “bump-hunting” searches are not sufficient; probing nonminimal dark sectors typically requires an analysis of the actual shapes of the distributions of relevant kinematic variables. We therefore begin by identifying those kinematic variables whose distributions are particularly suited to this task. However, as we demonstrate, this then leads to a number of additional subtleties, since cuts imposed on the data for the purpose of background reduction can at the same time have the unintended consequence of distorting these distributions in unexpected ways, thereby obscuring signals of new physics. We therefore proceed to study the correlations between several of the most popular relevant kinematic variables currently on the market, and investigate how imposing cuts on one or more of these variables can impact the distributions of others. Finally, we combine our results in order to assess the prospects for distinguishing nonminimal dark sectors in this channel at the upgraded LHC.

Azimuthal correlations in two hadron production in deep inelastic scattering of unpolarized leptons off a transversely polarized nucleon are discussed. Specifically, a simple approach for accessing ratios of structure functions corresponding to the Sivers effect and transversity induced single spin azimuthal asymmetries to unpolarized structure functions is presented. This approach is then applied to sample pseudodata generated by a modified version of the LEPTO Monte Carlo event generator that includes the Sivers effect. Using these data, it is shown that the azimuthal correlations in the Sivers-like structure functions and the unpolarized structure functions are significantly different. Collins-like single hadron asymmetries in a dihadron sample are also discussed, for which experimental results were recently presented by the COMPASS collaboration.

Over cosmic distances, astrophysical neutrino oscillations average out to a classical flavor propagation matrix $\mathcal{P}$. Thus, flavor ratios injected at the cosmic source $W_e,W_{\mu },W_{\tau }$ evolve to flavor ratios at Earthly detectors $w_e,w_{\mu },w_{\tau }$ according to $\overrightarrow{w}=\mathcal{P}\overrightarrow{W}$. The unitary constraint reduces the Euclidean octant to a “flavor triangle.” We prove a theorem that the area of the Earthly flavor triangle is proportional to $\text{Det}(\mathcal{P})$. One more constraint would further reduce the dimensionality of the flavor triangle at Earth (two) to a line (one). We discuss four such constraints. The first is the possibility of a vanishing determinant for $\mathcal{P}$. We give a formula for a unique $\delta ({\theta }_{ij})$ that yields the vanishing determinant. Next, we consider the thinness of the Earthly flavor triangle. We relate this thinness to the small deviations of the two angles ${\theta }_{32}$ and ${\theta }_{13}$ from maximal mixing and zero, respectively. Then we consider the confusion resulting from the tau-neutrino decay topologies, which are showers at low energy, “double-bang” showers in the PeV range, and a mixture of showers and tracks at even higher energies. We examine the simple low-energy regime, where there are just two topologies: $w_{\text{shower}}=w_e+w_{\tau }$ and $w_{\text{track}}=w_{\mu }$. We apply the statistical uncertainty to be expected from IceCube to this model. Finally, we consider ramifications of the expected lack of ${\nu }_{\tau }$ injection at cosmic sources. In particular, this constraint reduces the Earthly triangle to a boundary line of the triangle. Some tests of this “no ${\nu }_{\tau }$ injection” hypothesis are given.

In this work we use the gauge/gravity duality to study the anisotropy in the heavy quark potential in strongly coupled $\mathcal{N}=4$ super–Yang Mills (SYM) theory (both at zero and nonzero temperature) induced by a constant and uniform magnetic field $\mathcal{B}$. At zero temperature, the inclusion of the magnetic field decreases the attractive force between heavy quarks with respect to its $\mathcal{B}=0$ value and the force associated with the parallel potential is the least attractive force. We find that the same occurs at nonzero temperature and, thus, at least in the case of strongly coupled $\mathcal{N}=4$ SYM, the presence of a magnetic field generally weakens the interaction between heavy quarks in the plasma.

We consider equivariant wave maps from a fixed wormhole spacetime into the 3-sphere. This toy model is designed for gaining insight into the dissipation-by-dispersion phenomena, in particular the soliton resolution conjecture. We first prove that for each topological degree of the map there exists a unique static solution (harmonic map) that is linearly stable. Then, using the hyperboloidal formulation of the initial value problem, we give numerical evidence that every solution starting from smooth initial data of any topological degree evolves asymptotically to the harmonic map of the same degree. The late-time asymptotics of this relaxation process is described in detail.

Antineutrinos produced at nuclear reactors constitute a severe source of background for the detection of geoneutrinos, which bring to the Earth’s surface information about natural radioactivity in the whole planet. In this framework, we provide a reference worldwide model for antineutrinos from reactors, in view of reactors operational records yearly published by the International Atomic Energy Agency. We evaluate the expected signal from commercial reactors for ongoing (KamLAND and Borexino), planned ($\mathrm{SNO}+$), and proposed (Juno, RENO-50, LENA, and Hanohano) experimental sites. Uncertainties related to reactor antineutrino production, propagation, and detection processes are estimated using a Monte Carlo-based approach, which provides an overall site-dependent uncertainty on the signal in the geoneutrino energy window on the order of 3%. We also implement the off-equilibrium correction to the reference reactor spectra associated with the long-lived isotopes, and we estimate a 2.4% increase of the unoscillated event rate in the geoneutrino energy window due to the storage of spent nuclear fuels in the cooling pools. We predict that the research reactors contribute to less than 0.2% to the commercial reactor signal in the investigated 14 sites. We perform a multitemporal analysis of the expected reactor signal over a time lapse of ten years using reactor operational records collected in a comprehensive database published at www.fe.infn.it/antineutrino.

The search for continuous gravitational-wave signals requires the development of techniques that can effectively explore the low-significance regions of the candidate set. In this paper we present the methods that were developed for a search for continuous gravitational-wave signals from the Galactic Center [1]. First, we present a data-selection method that increases the sensitivity of the chosen data set by 20%–30% compared to the selection methods used in previous directed searches. Second, we introduce postprocessing methods that reliably rule out candidates that stem from random fluctuations or disturbances in the data. In the context of [J. Aasi et al., Phys. Rev. D 88, 102002 (2013)] their use enabled the investigation of marginal candidates (three standard deviations below the loudest expected candidate in Gaussian noise from the entire search). Such low-significance regions had not been explored in continuous gravitational-wave searches before. We finally present a new procedure for deriving upper limits on the gravitational-wave amplitude, which is several times faster with respect to the standard injection-and-search approach commonly used.

The aim of this paper is to confirm in new concrete examples that the semiclassical entropy of a three-dimensional Lifshitz black hole can be recovered through an anisotropic generalization of the Cardy formula derived from the growth of the number of states of a boundary nonrelativistic field theory. The role of the ground state in the bulk is played by the corresponding Lifshitz soliton obtained by a double Wick rotation. In order to achieve this task, we consider a scalar field nonminimally coupled to new massive gravity for which we study different classes of Lifshitz black holes as well as their respective solitons, including new solutions for a dynamical exponent $z=3$. The masses of the black holes and solitons are computed using the quasilocal formulation of conserved charges recently proposed by Gim et al. and based on the off-shell extension of the ADT formalism. We confirm the anisotropic Cardy formula for each of these examples, providing a stronger base for its general validity. Consistently, the first law of thermodynamics together with a Smarr formula are also verified.

In this article we investigate cylindrical thin-shell wormholes which are asymptotically anti-de Sitter. We analyze their stability under perturbations preserving the symmetry by using two different methods. We compare the results with those corresponding to the wormholes constructed from the Levi-Civita spacetime. We find that the configurations always require the presence of exotic matter at the throat, and, in the case of the linearized stability analysis, they can be stable for suitable values of the parameters.