Lorentz invariance violation introduced as a generic modification to particle dispersion relations is used to study high energy cosmic ray attenuation processes. It is shown to reproduce the same physical effects for vacuum Cherenkov radiation, as in some particular models with spontaneous breaking of Lorentz symmetry. This approximation is also implemented for the study of photon decay in vacuum, where stringent limits to the violation scale are derived from the direct observation of very high energy cosmic ray photon events on gamma telescopes. Photo production processes by cosmic ray primaries on photon background are also addressed, to show that Lorentz violation may turn off this attenuation process at energies above a well-defined secondary threshold.

Existence of different types of interference in the spectrum of radiation emitted by a doubly hard scattered electron is demonstrated. The spectrum develops oscillations in two regions: the hard, where they depend on the electron Lorentz factor, and the soft, where the oscillations depend on the electron scattering angles. This interference pattern owes to the presence of jetlike radiation configurations, formed by a piecewise-rectilinearly moving electron and the accompanying photon. The corresponding nondipole decomposition relation is derived. Notions describing proper field formation and interference, and presumably being applicable more generally, are discussed in detail.

We investigate the two-particle twist-3 distribution amplitudes (DAs) of the pseudoscalar mesons, in particular pseudoscalar [${\varphi }_{3;M}^P(x)$] and pseudotensor [${\varphi }_{3;M}^{\sigma }(x)$] DAs of the pion and kaon, in the light-front quark model based on the variational principle. We find that the behavior of the conformal symmetry in each meson distribution amplitude depends on the chiral-limit characteristics of the light-front trial wave function taken in the variational principle. We specifically take the two different light-front trial wave functions, Gaussian vs power-law type, and discuss their characteristics of the conformal symmetry in the chiral symmetry limit as well as their resulting degree of the conformal symmetry breaking in ${\varphi }_{3;M}^P(x)$ and ${\varphi }_{3;M}^{\sigma }(x)$ depending on the trial wave function taken in the computation. We present numerical results of transverse moments, Gegenbauer moments and $\xi$-moments and compare them with other available model estimates. The SU(3) flavor-symmetry breaking effect is also quantified with the numerical computation.

In this paper, we study the significance of the ${\mathrm{U}}_{\mathrm{Y}}(1)$ Chern-Simons term in general, and its baryonic contribution in particular, for the evolution of the matter asymmetries and the hypermagnetic field in the temperature range $100\mathrm{GeV}\le T\le 10\mathrm{TeV}$. We show that an initial helical hypermagnetic field, denoted by $B_Y^{(0)}$, can grow matter asymmetries from zero initial value. However, the growth which is initially quadratic with respect to $B_Y^{(0)}$ saturates for values larger than a critical value. The inclusion of the baryonic contribution reduces this critical value, leading to smaller final matter asymmetries. Meanwhile, $B_Y(T_{\mathrm{EW}})$ becomes slightly larger than $B_Y^{(0)}$. In the absence of the ${\mathrm{U}}_{\mathrm{Y}}(1)$ Chern-Simons term, the final values of matter asymmetries grow without saturation. Conversely, we show that an initial matter asymmetry can grow an initial seed of a hypermagnetic field, provided the Chern-Simons term is taken into account. The growth process saturates when the matter asymmetry drops abruptly. When the baryonic contribution is included, the saturation occurs at an earlier time, and $B_Y(T_{\mathrm{EW}})$ becomes larger. We also show that the baryonic asymmetry and the magnetic field strength can be within the acceptable range of present day data, provided the inverse cascade process is also taken into account; however, the magnetic field scale obtained from this simple model is much lower than the ones usually assumed for gamma-ray propagation.

Nonminimal composite Higgs scenarios can contain exotic Higgs states which, if observed at the Large Hadron Collider, will help to constrain the underlying UV structure of the strong dynamics. Doubly charged Higgs bosons are well-motivated scalar degrees of freedom in this context. Their phenomenology in typical composite scenarios can differ from well-established Higgs triplet extensions of the SM. Related search strategies are not necessarily adapted to such a scenario as a consequence. In this paper we discuss the sensitivity reach to doubly charged Higgs bosons with decays into pairs of same-sign $W$ bosons. While production cross sections are small, we show that significant constraints on $H^{\pm \pm }\to W^{\pm }{W}^{\pm }$ can be obtained, providing a new opportunity to constrain the potential composite structure of the TeV scale up to $m_{H^{\pm \pm }}\simeq 800\mathrm{GeV}$.

We calculate the one-loop corrections to TeV-scale dark matter annihilation in a model where the dark matter is described by an ${\mathrm{SU}(2)}_{\mathrm{L}}$ triplet of Majorana fermions, such as the wino. We use this framework to determine the high- and low-scale $\overline{\mathrm{MS}}$ matching coefficients at both the dark matter and weak boson mass scales at one loop. Part of this calculation has previously been performed in the literature numerically; we find our analytic result differs from the earlier work and discuss potential origins of this disagreement. Our result is used to extend the dark matter annihilation rate to next-to-leading $\text{logarithmic}+\mathcal{O}({\alpha }_2)$ corrections (${\mathrm{NLL}}^{\prime }$), which enables a precise determination of indirect detection signatures in present and upcoming experiments.

Prompt photon production is known as a powerful tool for testing perturbative QCD predictions and also the validity of parton densities in the nucleon and nuclei, especially of the gluon. In this work, we have performed a detailed study on this subject, focusing on the isolated prompt photon production in $p\text{−}\mathrm{Pb}$ collisions at forward rapidity at the LHC. The impact of input nuclear modifications obtained from different global analyses by various groups on several quantities has been investigated to estimate the order of magnitude of the difference between their predictions. We have also studied in detail the theoretical uncertainties in the results due to various sources. We found that there is a remarkable difference between the predictions from the nCTEQ15 and other groups in all ranges of photon transverse momentum $p_{\mathrm{T}}^{\gamma }$. Their differences become more explicit in the calculation of the nuclear modification ratio and also the yield asymmetry between the forward and backward rapidities rather than single differential cross sections. We emphasize that future measurements with ALICE will be very useful, not only for decreasing the uncertainty of the gluon nuclear modification, but also to accurately determine its central values, especially in the shadowing region.

The heavy baryon ${\mathrm{\Lambda }}_b$ is regarded as composed of a heavy quark and a scalar diquark which has good spin and isospin quantum numbers. In this picture, we calculate the electromagnetic form factors of ${\mathrm{\Lambda }}_b$ in the Bethe-Salpeter equation approach in the spacelike region. We find that the shapes of the electromagnetic form factors of ${\mathrm{\Lambda }}_b$ are similar to those of $\mathrm{\Lambda }$, with a peak at $\omega =1$ (for the magnetic form factor) and $\omega \simeq 1.1$ (for the electric form factor)($\omega =v^{\prime }·v$ is the velocity transfer between the initial state (with velocity $v$) and the final state (with velocity $v^{\prime }$) of ${\mathrm{\Lambda }}_b$), but the amplitudes are much smaller than those of $\mathrm{\Lambda }$.

Geoneutrinos are electron antineutrinos (${\overline{\nu }}_e$) generated by the beta decays of radionuclides naturally occurring inside the Earth, in particular ${}^{238}\mathrm{U}$, ${}^{232}\mathrm{Th}$, and ${}^{40}\mathrm{K}$. Measurement of these neutrinos provides powerful constraints on the radiogenic heat of the Earth and tests on the Earth models. Since the prediction of ${\overline{\nu }}_e$’s in geoneutrino flux is subject to neutrino oscillation effects, we performed a calculation including detailed oscillation analysis in the propagation of geoneutrinos and reactor neutrinos generated around the Earth. The expected geoneutrino signal, the reactor neutrino background rates, and the systematic error budget are provided for a proposed 3 kt neutrino detector at the Jinping underground lab in Sichuan, China. In addition, we evaluated sensitivities for the geoneutrino flux, Th/U ratio, and power of a possible fission reactor in the interior of the Earth.

The preceding Comment claims that the paper “Quantum Raychaudhuri equation” by S. Das, [Phys. Rev. D 89, 084068 (2014)] has “problematic points” with regards to its derivation and implications. We show below that the above claim is incorrect, and that there are no problems with the results of Das’s paper or its implications.

We address the validity of the formalism and results presented in S. Das, Phys. Rev. D 89, 084068 (2014) with regard to the quantum Raychaudhuri equation. The author obtained the so-called quantum Raychaudhuri equation by replacing classical geodesics with quantal trajectories arising from Bhommian mechanics. The resulting modified equation was used to draw some conclusions about the inevitability of focusing and the formation of conjugate points and therefore singularity. We show that the whole procedure is full of problematic points, on both physical relevancy and mathematical correctness. In particular, we illustrate the problems associated with the technical derivation of the so-called quantum Raychaudhuri equation, as well as its invalid physical implications.

We introduce a lattice fermion model in one spatial dimension with supersymmetry (SUSY) but without particle number conservation. The Hamiltonian is defined as the anticommutator of two nilpotent supercharges $Q$ and $Q^{†}$. Each supercharge is built solely from spinless fermion operators and depends on a parameter $g$. The system is strongly interacting for small $g$, and in the extreme limit $g=0$, the number of zero-energy ground states grows exponentially with the system size. By contrast, in the large-$g$ limit, the system is noninteracting and SUSY is broken spontaneously. We study the model for modest values of $g$ and show that under certain conditions spontaneous SUSY breaking occurs in both finite and infinite chains. We analyze the low-energy excitations both analytically and numerically. Our analysis suggests that the Nambu-Goldstone fermions accompanying the spontaneous SUSY breaking have cubic dispersion at low energies.

In this paper, we study the problem of gauge invariance of the first order transition amplitudes in de Sitter QED in the Coulomb gauge. We consider the gauge transformations which preserve the Coulomb gauge, that contain the gradient of the gauge function. The final results prove that the first order transition amplitudes do not change at a gradient transformation of the vector potential because the only allowed transformation is $\mathrm{\Lambda }=0$. Our results suggest that the remarks made in the comment by Nicolaevici and Farkas [this issue, Phys. Rev. D 95, 048501 (2017)] are not directly applicable to the results in our paper since their proposed gauge transformations do not preserve the Coulomb gauge.

We point out that the transition probabilities used in a recent perturbative calculation of pair creation in an external magnetic field in the expanding de Sitter space with the in and out fermion states defined by the Bunch-Davies modes [C. Crucean and M. A. Baloi, Phys. Rev. D 93, 044070 (2016)] are gauge-dependent quantities. We examine the gauge variations of these amplitudes assuming a decoupling of the interaction at infinite times, which allows us to conclude that the source of the problem lies in the nonoscillatory behavior of the fermion current in the infinite future.

Extending the works of [Phys. Rev. Lett. 115, 161304 (2015)] and [Phys. Rev. D 93, 064014 (2016)], we study three dimensional Euclidean higher spin gravity with negative cosmological constant. This theory can be formulated in terms of $SL(N,\mathbb{C})$ Chern-Simons theory. By introducing auxiliary fields, we rewrite it in a supersymmetric way and compute its partition function exactly by using the localization method. We obtain a good expression for the partition function in terms of characters for the vacuum and primaries in 2D unitary conformal field theory with ${\mathcal{W}}_N$ symmetry. We also check that the coefficients of the character expansion are positive integers and exhibit Cardy formula in the large central charge limit.

A photon surface $S$ is defined as a three-dimensional timelike hypersurface such that any null geodesic initially tangent to $S$ continues to be included in $S$, like $r=3M$ of the Schwarzschild spacetime. Using analytic solutions to static perturbations of a Schwarzschild spacetime, we examine whether a nonspherical spacetime can possess a distorted static photon surface. It is shown that if the region outside of $r=3M$ is vacuum, no distorted photon surface can be present. Therefore, we establish the perturbative uniqueness for an asymptotically flat vacuum spacetime with a static photon surface. It is also pointed out that if matter is present in the outside region, there is a possibility that a distorted photon surface could form.

The applications of numerical relativity to cosmology are on the rise, contributing insight into such cosmological problems as structure formation, primordial phase transitions, gravitational-wave generation, and inflation. In this paper, I present the infrastructure for the computation of inhomogeneous dust cosmologies which was used recently to measure the effect of nonlinear inhomogeneity on the cosmic expansion rate. I illustrate the code’s architecture, provide evidence for its correctness in a number of familiar cosmological settings, and evaluate its parallel performance for grids of up to several billion points. The code, which is available as free software, is based on the Einstein Toolkit infrastructure, and in particular leverages the automated code generation capabilities provided by its component Kranc.

We present new ($3+1$)-dimensional numerical relativity simulations of the binary neutron star (BNS) mergers that take into account the NS spins. We consider different spin configurations, aligned or antialigned to the orbital angular momentum, for equal- and unequal-mass BNSs and for two equations of state. All the simulations employ quasiequilibrium circular initial data in the constant rotational velocity approach, i.e. they are consistent with the Einstein equations and in hydrodynamical equilibrium. We study the NS rotation effect on the energetics, the gravitational waves (GWs) and on the possible electromagnetic (EM) emission associated to dynamical mass ejecta. For dimensionless spin magnitudes of $\chi \sim 0.1$ we find that both spin-orbit interactions and spin-induced quadrupole deformations affect the late-inspiral merger dynamics. The latter is, however, dominated by finite-size effects. Spin (tidal) effects contribute to GW phase differences up to $\sim 5$ (20) radians accumulated during the last eight orbits to merger. Similarly, after merger the collapse time of the remnant and the GW spectrogram are affected by the NSs rotation. Spin effects in dynamical ejecta are clearly observed in unequal-mass systems in which mass ejection originates from the tidal tail of the companion. Consequently kilonovae and other EM counterparts are affected by spins. We find that spin aligned to the orbital angular momentum leads to brighter EM counterparts than antialigned spin with luminosities up to a factor of 2 higher.

We study the stability of singularity-free cosmological solutions with a positive cosmological constant based on the projectable Hořava-Lifshitz (HL) theory. In the HL theory, the isotropic and homogeneous cosmological solutions with bounce can be realized if the spatial curvature is nonzero. By performing a perturbation analysis around nonflat Friedmann-Lemaître-Robertson-Walker (FLRW) spacetime, we derive a quadratic action and discuss the stability, i.e., ghost and tachyon-free conditions. Although the squared effective mass of scalar perturbation must be negative in the infrared regime, we can avoid tachyon instability by considering strong Hubble friction. Additionally, we estimate the backreaction from the perturbations on the background geometry, especially against an anisotropic perturbation in closed FLRW spacetime. It turns out that certain types of bouncing solution may be spoiled even if all perturbation modes are stable.

The spontaneous pair production of charged scalars in a near-extremal Kerr-Newman (KN) black hole is analytically studied. It is shown that the existence condition for pair production is equivalent to the violation of the Breitenlohner-Freedman bound in an ${\mathrm{AdS}}_2$ space. The mean number of produced pairs in the extremal black hole has a thermal interpretation, in which the effective temperature for the Schwinger effect in the ${\mathrm{AdS}}_2$ space persistently holds, while the mean number in the near-extremal black hole has an additional factor of the Schwinger effect in the Rindler space. In addition, the holographic dual conformal field theory (CFT) descriptions of charged scalar pair production are realized in both the $J$ and $Q$ pictures in terms of the KN/CFTs correspondence.