If local supersymmetry is the correct extension of the standard model of particle physics, then following inflation the early Universe would have been populated by gravitinos produced from scatterings in the hot plasma during reheating. Their abundance is directly related to the magnitude of the reheating temperature. The gravitino lifetime is fixed as a function of its mass, and for gravitinos with lifetimes longer than the age of the Universe at redshift $z\simeq 2\times 10^6$ (or roughly $6\times 10^6\mathrm{s}$), decay products can produce spectral distortion of the cosmic microwave background. Currently available COBE/FIRAS limits on spectral distortion can, in certain cases, already be competitive with respect to cosmological constraints from primordial nucleosynthesis for some gravitino decay scenarios. We show how the sensitivity limits on $\mu$ and $y$ distortions that can be reached with current technology will improve constraints and possibly rule out a significant portion of the parameter space for gravitino masses and inflation reheating temperatures.

We investigate a possible method for determining the progenitors of black-hole (BH) mergers observed via their gravitational wave (GW) signal. We argue that measurements of the cross-correlation of the GW events with overlapping galaxy catalogs may provide an additional tool in determining if BH mergers trace the stellar mass of the Universe, as would be expected from mergers of the end points of stellar evolution. If, on the other hand, the BHs are of primordial origin, as has been recently suggested, their merging would be preferentially hosted by lower biased objects and thus have a lower cross-correlation with luminous galaxies. Here, we forecast the expected precision of the cross-correlation measurement for current and future GW detectors such as LIGO and the Einstein Telescope. We then predict how well these instruments can distinguish the model that identifies high-mass BH-BH mergers as the merger of primordial black holes that constitute the dark matter in the Universe from more traditional astrophysical sources.

Giant pulsar frequency glitches as detected in the emblematic Vela pulsar have long been thought to be the manifestation of a neutron superfluid permeating the inner crust of a neutron star. However, this superfluid has been recently found to be entrained by the crust, and as a consequence it does not carry enough angular momentum to explain giant glitches. The extent to which pulsar-timing observations can be reconciled with the standard vortex-mediated glitch theory is studied considering the current uncertainties on dense-matter properties. To this end, the crustal moment of inertia of glitching pulsars is calculated employing a series of different unified dense-matter equations of state.

Using the analytic modeling of the electromagnetic cascades compared with more precise numerical simulations, we describe the physical properties of electromagnetic cascades developing in the universe on cosmic microwave background and extragalactic background light radiations. A cascade is initiated by very-high-energy photon or electron, and the remnant photons at large distance have two-component energy spectrum, $\propto E^{-2}$ ($\propto E^{-1.9}$ in numerical simulations) produced at the cascade multiplication stage and $\propto E^{-3/2}$ from Inverse Compton electron cooling at low energies. The most noticeable property of the cascade spectrum in analytic modeling is “strong universality,” which includes the standard energy spectrum and the energy density of the cascade ${\omega }_{\mathrm{cas}}$ as its only numerical parameter. Using numerical simulations of the cascade spectrum and comparing it with recent Fermi LAT spectrum, we obtained the upper limit on ${\omega }_{\mathrm{cas}}$ stronger than in previous works. The new feature of the analysis is the “$E_{\max }$ rule.” We investigate the dependence of ${\omega }_{\mathrm{cas}}$ on the distribution of sources, distinguishing two cases of universality: the strong and weak ones.

We present the most general gauge-invariant action functional for coupled 1- and 2-form gauge fields with kinetic terms in generic dimensions, i.e., dropping eventual contributions that can be added in particular space-time dimensions only such as higher Chern-Simons terms. After appropriate field redefinitions it coincides with a truncation of the Samtleben-Szegin-Wimmer action. In the process one sees explicitly how the existence of a gauge-invariant functional enforces that the most general semistrict Lie 2-algebra describing the bundle of a non-Abelian gerbe gets reduced to a very particular structure, which, after the field redefinition, can be identified with the one of an enhanced Leibniz algebra. This is the first step towards a systematic construction of such functionals for higher gauge theories, with kinetic terms for a tower of gauge fields up to some highest form degree $p$, solved here for $p=2$.

We discuss a scenario in which the diphoton enhancement at $M_{\gamma \gamma }=750\mathrm{GeV}$, observed by the ATLAS and CMS collaborations, is a neutral technipion ${\tilde{\pi }}^0$. We consider two distinct minimal models for the dynamical electroweak symmetry breaking. In a first one, two-flavor vectorlike technicolor (VTC) model, we assume that the two-photon fusion is a dominant production mechanism. We include $\gamma \gamma \to {\tilde{\pi }}^0$ and production of technipion associated with one or two jets. All the considered mechanisms give similar contributions. With the strong Yukawa (technipion-techniquark) coupling $g_{\mathrm{TC}}\simeq 20$ we roughly obtain the measured cross section of the “signal” with a small difficulty of simultaneous description of the $\sqrt{s}=13\mathrm{TeV}$ and $\sqrt{s}=8\mathrm{TeV}$ data. With such values of $g_{\mathrm{TC}}$ we get a relatively small ${\mathrm{\Gamma }}_{\text{tot}}$. In a second approach, one-family walking technicolor (WTC) model, the isoscalar technipion is produced dominantly via the gluon-gluon fusion. We also discuss the size of the signal at lower energies (LHC, Tevatron) for $\gamma \gamma$ (VTC) and jet-jet (WTC) final states and check consistency with the existing experimental data. We predict a measurable cross section for ${\tilde{\pi }}^0$ production associated with one or two soft jets. The technipion signal in both models is compared with the SM background diphoton contributions. We observe the dominance of the inelastic-inelastic mechanism for $\gamma \gamma$ induced processes. In the VTC scenario, we predict the signal cross section for purely exclusive $pp\to pp\gamma \gamma$ processes at $\sqrt{s}=13\mathrm{TeV}$ to be about 0.2 fb. Such a cross section would be, however, difficult to measure with the planned integrated luminosity. In all considered cases the signal is below the background or/and below the threshold set by statistics.

We derive effective Polyakov line actions for SU(3) gauge theories with staggered dynamical fermions, for a small sample of lattice couplings, lattice actions, and lattice extensions in the time direction. The derivation is via the method of relative weights, and the theories are solved at finite chemical potential by mean field theory. We find in some instances that the long-range couplings in the effective action are very important to the phase structure, and that these couplings are responsible for long-lived metastable states in the effective theory. Only one of these states corresponds to the underlying lattice gauge theory.

Recently, several anomalies in flavor physics have been observed, and it was noticed that leptoquarks might account for the deviations from the Standard Model. In this work, we examine the effects of new physics originating from a scalar leptoquark model on the kaon sector. The leptoquark we consider is a TeV-scale particle and within the reach of the LHC. We use the existing experimental data on the several kaon processes including $K^0-{\overline{K}}^0$ mixing; rare decays $K^{+}\to {\pi }^{+}\nu \overline{\nu }$, $K_L\to {\pi }^0\nu \overline{\nu }$; the short-distance part of $K_L\to {\mu }^{+}{\mu }^{-}$; and lepton-flavor-violating decay $K_L\to {\mu }^{\pm }{e}^{\mp }$ to obtain useful constraints on the model.

Starting from a relativistic Lagrangian for pseudoscalar Goldstone bosons and vector mesons in the antisymmetric tensor representation, a one-loop calculation is performed to pin down the divergent structures that appear for the effective low-energy action at chiral orders $Q^2$ and $Q^4$. The corresponding renormalization-scale dependencies of all low-energy constants up to chiral order $Q^4$ are determined. Calculations are carried out for both the pseudoscalar octet and the pseudoscalar nonet, the latter in the framework of chiral perturbation theory in the limit of a large number of colors.

We present our work on the simulation of the early stages of heavy-ion collisions with finite longitudinal thickness in the laboratory frame in $3+1$ dimensions. In particular we study the effects of nuclear thickness on the production of a glasma state in the McLerran-Venugopalan model within the color glass condensate framework. A finite thickness enables us to describe nuclei at lower energies, but forces us to abandon boost invariance. As a consequence, random classical color sources within the nuclei have to be included in the simulation, which is achieved by using the colored particle-in-cell method. We show that the description in the laboratory frame agrees with boost-invariant approaches as a limiting case. Furthermore we investigate collisions beyond boost invariance, in particular the pressure anisotropy in the glasma.

Many models of physics beyond the standard model predict the existence of new Abelian forces with new gauge bosons mediating interactions between “dark sectors” and the standard model. We report a search for a dark boson $Z^{\prime }$ coupling only to the second and third generations of leptons in the reaction $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}{Z}^{\prime },Z^{\prime }\to {\mu }^{+}{\mu }^{-}$ using $514{\mathrm{fb}}^{-1}$ of data collected by the BABAR experiment. No significant signal is observed for $Z^{\prime }$ masses in the range 0.212–10 GeV. Limits on the coupling parameter $g^{\prime }$ as low as $7\times {10}^{-4}$ are derived, leading to improvements in the bounds compared to those previously derived from neutrino experiments.

The fits presented in the paper had an error in $L_{\mathrm{isco}}$ and were also not optimized for the aligned spin case. Of these two, the latter has a larger effect when using the formula for extrapolation. In addition, there were errors in the remnant spins obtained from the radiated angular momentum in Table XVIII.

Recently, two of us have found numerically rotating Ellis wormholes as solutions of four-dimensional Einstein gravity coupled to a phantom field. In this paper, we investigate possible observational signatures to identify similar objects in the Universe. These symmetric wormholes have a mass and are compact, so they may look like black holes. We study the iron line profile in the x-ray reflection spectrum of a thin accretion disk around rotating Ellis wormholes and we find some specific observational signatures that can be used to distinguish these objects from Kerr black holes. We simulate some observations with XIS/Suzaku assuming typical parameters for a bright active galactic nucleus and we conclude that current x-ray missions cannot apply strong constraints.

In this work, we study the propagation of scalar fields in the gravitational background of a higher-dimensional Schwarzschild–de Sitter black hole as well as on the projected-on-the-brane four-dimensional background. The scalar fields have also a nonminimal coupling to the corresponding, bulk or brane, scalar curvature. We perform a comprehensive study by deriving exact numerical results for the greybody factors, and study their profile in terms of particle and spacetime properties. We then proceed to derive the Hawking radiation spectra for a higher-dimensional Schwarzschild–de Sitter black hole, and we study both bulk and brane channels. We demonstrate that the nonminimal field coupling, which creates an effective mass term for the fields, suppresses the energy emission rates while the cosmological constant assumes a dual role. By computing the relative energy rates and the total emissivity ratio for bulk and brane emission, we demonstrate that the combined effect of a large number of extra dimensions and value of the field coupling gives to the bulk channel the clear domination in the bulk-brane energy balance.

We study the radial and nonradial motion of massive test particles and photons in a three-parameter family of cylindrically symmetric wormholes $\text{WhC}{\mathrm{R}}^{\mathrm{e}}$ generated by the electromagnetic, dilaton, and scalar fields, with particular attention paid to the extent to which the wormhole is traversable. The wormholes are not asymptotically flat and contain a curvature singularity at one end of the wormhole. In the case of nonradial motion with conserved energy and angular momentum along a hypersurface $z=\text{const}$ (“planar orbits”) we show that, as in the Kerr and Schwarzschild geometries, we should distinguish between orbits with impact parameters greater or less than a certain critical value $D_c$, which corresponds to the unstable circular orbit of radius $u_c$. For $D^2>D_c^2$ there are two kinds of orbits: orbits of the first kind arrive from infinity and turn around at the orbit’s minimum radial coordinate $u$ (“pericenter”) greater than $u_c$, whereas orbits of the second kind turn around at maximum radial coordinate $u$ (“apocenter”) less than $u_c$ and terminate at the singularity at $u=-\infty$. For $D=D_c$ orbits of the first and second kinds merge and both orbits spiral an infinite number of times toward the unstable circular orbit $u=u_c$. For $D^2<D_c^2$ we have only orbits of one kind: starting at infinity, they cross the wormhole throat and terminate at the singularity.

We consider the inflationary model in which the inflaton $\varphi$ couples to another scalar field $\chi$ via the interaction $g^2(\varphi -{\varphi }_0{)}^2{\chi }^2$ with a small coupling constant $g$ ($g^2\sim {10}^{-7}$). We assume that there is a sequence of “trapping points” ${\varphi }_{0i}$ along the inflationary trajectory where particles of the $\chi$ field become massless and are rather effectively produced. We calculate the power spectrum of inflaton field fluctuations originating from a backreaction of $\chi$ particles produced using the Schwinger’s “in-in” formalism. We show that the primary curvature power spectrum produced by these backreaction effects is blue, which leads to a strong overproduction of primordial black holes (PBHs) in the subsequent radiation era.

In Lemaître–Tolman (L–T) models, light rays emitted radially at the Big Bang (BB) at such radial coordinates $r$ where the bang-time function $t_B(r)$ has $\mathrm{d}{t}_B/\mathrm{d}r\ne 0$ reach every observer with infinite blueshift, $z=-1$. Consequently, there exist rays, emitted soon after the BB, that will reach later observers with finite blueshift ($-1<z<0$). But in spacetimes without symmetry there are no radial directions. The question thus arises whether blueshifts can exist at all in the Szekeres models that contain L–T as a limit, but in general have no symmetry. The aim of the present paper is to show that strong blueshifts can be generated in quasispherical Szekeres (QSS) models. It is shown that in an axially symmetric QSS model, infinite blueshift can appear only on axial rays, which intersect every space orthogonal to the dust flow on the symmetry axis. In an exemplary QSS model it is numerically shown that if such a ray is emitted from the Big Bang where $\mathrm{d}{t}_B/\mathrm{d}r\ne 0$, then indeed observers see it with $z\approx -1$. Rays emitted shortly after the BB and running close to the symmetry axis will reach the observers with a strong blueshift, too. Then, in a toy QSS model that has no symmetry, it was shown by numerical calculations that two null lines exist such that rays in their vicinity have redshift profiles similar to those in a vicinity of the axial rays in the axially symmetric case. This indicates that rays generating infinite blueshifts exist in general QSS spacetimes and are concentrated around two directions.

Future large liquid-scintillator detectors can be implemented to observe neutrinos from a core-collapse supernova in our Galaxy in various reaction channels: (1) the inverse beta decay ${\overline{\nu }}_e+p\to n+e^{+}$, (2) the elastic neutrino-proton scattering $\nu +p\to \nu +p$, (3) the elastic neutrino-electron scattering $\nu +e^{-}\to \nu +e^{-}$, (4) the charged-current ${\nu }_e$ interaction ${\nu }_e+{}^{12}\mathrm{C}\to e^{-}+{}^{12}\mathrm{N}$, (5) the charged-current ${\overline{\nu }}_e$ interaction ${\overline{\nu }}_e+{}^{12}\mathrm{C}\to e^{+}+{}^{12}\mathrm{B}$, and (6) the neutral-current interaction $\nu +{}^{12}\mathrm{C}\to \nu +{}^{12}{\mathrm{C}}^{*}$. The less abundant ${}^{13}\mathrm{C}$ atoms in the liquid scintillator are also considered as a target, and both the charged-current interaction ${\nu }_e+{}^{13}\mathrm{C}\to e^{-}+{}^{13}\mathrm{N}$ and the neutral-current interaction $\nu +{}^{13}\mathrm{C}\to \nu +{{}^{13}\mathrm{C}}^{*}$ are taken into account. In this work, we show for the first time that a global analysis of all these channels at a single liquid-scintillator detector, such as Jiangmen Underground Neutrino Observatory, is very important to test the average-energy hierarchy of supernova neutrinos and how the total energy is partitioned among neutrino flavors. In addition, the dominant channels for reconstructing neutrino spectra and the impact of other channels are discussed in great detail.

We investigate the instability of a classical Yang-Mills field in an expanding geometry under a color magnetic background field within the linear regime. We consider homogeneous, boost-invariant, and time-dependent color magnetic fields simulating the glasma configuration. We introduce the conformal coordinates which enable us to map an expanding problem approximately into a nonexpanding problem. We find that the fluctuations with finite longitudinal momenta can grow exponentially due to parametric instability. Fluctuations with finite transverse momenta can also show parametric instability, but their momenta are restricted to be small. The most unstable modes start to grow exponentially in the early stage of the dynamics, and they may affect the thermalization in heavy-ion collisions.

We consider a simplified model in which Majorana fermion dark matter annihilates to charged fermions through the exchange of charged mediators. We consider the gamma-ray signals arising from the processes $XX\to \overline{f}f\gamma$, $\gamma \gamma$, and $\gamma Z$ in the most general case, including nontrivial fermion mass and nontrivial left-right mixing and the $CP$-violating phase for the charged mediators. In particular, we find the most general spectrum for internal bremsstrahlung, which interpolates between the regimes dominated by virtual internal bremsstrahlung and by final state radiation. We also examine the variation in the ratio $\sigma (\gamma \gamma )/\sigma (\gamma Z)$ and the helicity asymmetry in the $XX\to \gamma \gamma$ process, each as a function of the mixing angle and $CP$-violating phase. As an application, we apply these results to searches for a class of minimal supersymmetric Standard Model models.