Using a standard cooling method for $SU(3)$ lattice gauge fields, constant Abelian magnetic field configurations are extracted after dyon-antidyon constituents forming metastable $Q=0$ configurations have annihilated. These so-called Dirac sheets, standard and nonstandard ones, corresponding to the two $U(1)$ subgroups of the $SU(3)$ group, have been found to be stable if emerging from the confined phase, close to the deconfinement phase transition, with sufficiently nontrivial Polyakov loop values. On a finite lattice we find a nice agreement of the numerical observations with the analytic predictions concerning the stability of Dirac sheets depending on the value of the Polyakov loop.

We study the production of two electroweak vector bosons in association with a jet via gluon fusion. In particular we consider the production of $\gamma Zg$, $ZZg$ and $W^{+}{W}^{-}g$ at hadron colliders and compute their cross sections. Such processes have already produced a large number of events at the Large Hadron Collider by now. These processes can be background to the Higgs boson production and a number of beyond the standard model scenarios. Therefore it is important to know the values of their contribution. The calculation is based on conventional Feynman diagram approach. In particular we find that the process $gg\to ZZg$ can make a significant contribution to the process $pp\to ZZ+\mathrm{\text{jet}}$.

The differential cross section for the production of direct photons in $p+p$ collisions at $\sqrt{s}=200\mathrm{GeV}$ at midrapidity was measured in the PHENIX detector at the Relativistic Heavy Ion Collider. Inclusive direct photons were measured in the transverse momentum range from $5.5–25\mathrm{GeV}/c$, extending the range beyond previous measurements. Event structure was studied with an isolation criterion. Next-to-leading-order perturbative-quantum-chromodynamics calculations give a good description of the spectrum. When the cross section is expressed versus $x_T$, the PHENIX data are seen to be in agreement with measurements from other experiments at different center-of-mass energies.

We report measurements of the decays $B^{-}\to D_s^{(*)+}{K}^{-}{\ell }^{-}{\overline{\nu }}_{\ell }$ in a data sample containing $657\times {10}^{6}B\overline{B}$ pairs collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. We observe a signal with a significance of $6\sigma$ for the combined $D_s$ and $D_s^{*}$ modes and find the first evidence of the $B^{-}\to D_s^{+}{K}^{-}{\ell }^{-}{\overline{\nu }}_{\ell }$ decay with a significance of $3.4\sigma$. We measure the following branching fractions: $\mathcal{B}(B^{-}\to D_s^{+}{K}^{-}{\ell }^{-}{\overline{\nu }}_{\ell })=(0.30\pm 0.09(\mathrm{stat}{)}_{-0.08}^{+0.11}(\mathrm{syst}))\times {10}^{-3}$ and $\mathcal{B}(B^{-}\to D_s^{(*)+}{K}^{-}{\ell }^{-}{\overline{\nu }}_{\ell })=(0.59\pm 0.12(\mathrm{stat})\pm 0.15(\mathrm{syst}))\times {10}^{-3}$ and set an upper limit $\mathcal{B}(B^{-}\to D_s^{*+}{K}^{-}{\ell }^{-}{\overline{\nu }}_{\ell })<0.56\times {10}^{-3}$ at the 90% confidence level. We also present the first measurement of the $D_s^{+}{K}^{-}$ invariant mass distribution in these decays, which is dominated by a prominent peak around $2.6\mathrm{GeV}/c^2$.

Under a Scherk-Schwarz compactification, the anti-de Sitter soliton and black brane provide a dual description to a confinement/deconfinement phase transition. We extend this construction to asymptotically Lifshitz spacetimes. In particular, we show that there must be a phase transition between the soliton and black hole if the solutions exist. We also construct these solutions numerically and compute the phase diagram.

Based on Maldacena’s description of an eternal anti–de Sitter (AdS) black hole, we reassess the thermo field dynamics (TFD) formalism in the context of the AdS/CFT correspondence. The model studied here involves the maximally extended AdS-Schwarschild solution and two (noninteracting) copies of the conformal field theory (CFT) associated to the global AdS spacetime, along with an extension of the string by imposing natural gluing conditions in the horizon. We show that the gluing conditions in the horizon define a string boundary state which is identified with the TFD thermal vacuum, globally defined in the Kruskal extension of the AdS black hole. We emphasize the connection of this picture with unitary $SU(1,1)$ TFD formulation, and we show that information about the bulk and the conformal boundary is present in the $SU(1,1)$ parameters. Using the unitary $SU(1,1)$ TFD formulation, a canonical prescription for calculating the world sheet real time thermal Green’s function is made, and the entropy associated with the entanglement of the two CFT’s is calculated.

The surprising discovery by Major Atmospheric Gamma Imaging Cherenkov Telescope (MAGIC) of an intense, rapidly varying emission in the energy range 70–400 GeV from the flat spectrum radio quasar PKS $1222+216$ represents a challenge for all interpretative scenarios. Indeed, in order to avoid absorption of $\gamma$ rays in the dense ultraviolet radiation field of the broad line region, one is forced to invoke some unconventional astrophysical picture, like for instance the existence of a very compact ($r\sim {10}^{14}\mathrm{cm}$) emitting blob at a large distance ($R\sim {10}^{18}\mathrm{cm}$) from the jet base. We offer the investigation of a scenario based on the standard blazar model for PKS $1222+216$ where $\gamma$ rays are produced close to the central engine, but we add the new assumption that inside the source photons can oscillate into axion-like particles (ALPs), which are a generic prediction of several extensions of the Standard Model of elementary particle interactions. As a result, a considerable fraction of very-high-energy photons can escape absorption from the broad line region through the mechanism of photon-ALP oscillations much in the same way as they largely avoid absorption from extragalactic background light when propagating over cosmic distances in the presence of large-scale magnetic fields in the nG range. In addition we show that the above Major Atmospheric Gamma Imaging Cherenkov Telescope (MAGIC) observations and the simultaneous Fermi/Large Area Telescope (LAT) observations in the energy range 0.3–3 GeV can both be explained by a standard spectral energy distribution for experimentally allowed values of the model parameters. In particular, we need a very light ALP just like in the case of photon-ALP oscillations in cosmic space. Moreover, we find it quite tantalizing that the most favorable value of the photon-ALP coupling happens to be the same in both situations. Although our ALPs cannot contribute to the cold dark matter, they are a viable candidate for the quintessential dark energy. An astrophysical test of our scenario is proposed and an independent laboratory check for the existence of an ALP with the properties required by our picture will be performed with the planned upgrade of the photon regeneration experiment ALPS at Deutsches Elektronen-Synchrotron (DESY) and with the next generation of solar axion detectors like International Axion Observatory (IAXO).

We discuss the possible relation between certain geometrical properties of the loop space and energy evolution of the cusped Wilson exponentials defined on the light cone. Analysis of the area differential equations for this special class of the Wilson loops calls for careful treatment of the ultraviolet and rapidity divergences which make those loops nonmultiplicatively renormalizable. We propose to consider the renormalization properties of the light-cone cusped Wilson loops from the point of view of the universal quantum dynamical approach introduced by Schwinger. We discuss the relevance of the Makeenko-Migdal loop equations supplied with the modified Schwinger principle to the energy evolution of some phenomenologically significant objects, such as transverse momentum dependent distribution functions, collinear parton densities at large $x$, etc.

We show the existence of Bogomol’nyi-Prasad-Sommerfield (BPS) magnetic monopoles in a generalized Yang-Mills-Higgs model which is controlled by two positive functions, $g({\varphi }^a{\varphi }^a)$ and $f({\varphi }^a{\varphi }^a)$. This effective model, in principle, would describe the dynamics of the nonabelian fields in a chromoelectric media. We check the consistency of our generalized construction by analyzing an explicit case ruled by a parameter $\beta$. We also use the well-known spherically symmetric Ansatz to attain the corresponding self-dual equations describing the topological solutions. The overall conclusion is that the new solutions behave around the canonical one, with smaller or greater characteristic length depending on the values of $\beta$.

We report that a class of three-dimensional bimetric theories contains asymptotically flat solutions. These spacetimes can be cast in a set of asymptotic conditions at null infinity which are preserved under the infinite-dimensional Bondi-Metzner-Sachs group. Moreover, the algebra of the canonical generators exhibits a central extension. The possibility that these solutions describe regular black holes is also discussed.

A 2-parameter inhomogeneous cosmology in Brans-Dicke theory, obtained by conformally transforming the Husain-Martinez-Nuñez scalar field solution of the Einstein equations is studied and interpreted physically. According to the values of the parameters it describes a wormhole or a naked singularity. The reasons why there is not a one-to-one correspondence between conformal copies of this metric are discussed.

Imposing the Petrov-like boundary condition on the hypersurface at finite cutoff, we derive the hydrodynamic equation on the hypersurface from the bulk Einstein equation with an electromagnetic field in the near-horizon limit. We first get the general framework for spacetime with a matter field, and then derive the incompressible Navier-Stokes equations for black holes with electric charge and magnetic charge, respectively. Especially, in the magnetic case, the standard magnetohydrodynamic equations will arise due to the existence of the background electromagnetic field on the hypersurface.

In the present paper, we investigate the Hawking radiation of asymptotically nonflat dyonic black holes in 4D Einstein-Maxwell-dilaton gravity in semiclassical approximation. We show that the problem allows an exact analytical treatment and we compute exactly the semiclassical radiation spectrum of both nonextremal and extremal black holes under consideration. In the high-frequency regime, we find that the Hawking temperature does not agree with the surface gravity when the magnetic charge is nonzero. Even more surprisingly, the Hawking temperature is independent of the black hole intrinsic characteristics, as the mass and magnetic charge, and depends only on the linear dilaton background parameter.

Penrose conjectured a connection between entropy and Weyl curvature of the Universe. This is plausible, as the almost homogeneous and isotropic Universe at the onset of structure formation has negligible Weyl curvature, which then grows (relative to the Ricci curvature) due to the formation of large-scale structure, and thus reminds us of the second law of thermodynamics. We study two scalar measures to quantify the deviations from a homogeneous and isotropic space-time: the relative information entropy and a Weyl tensor invariant, and show their relation to the averaging problem. We calculate these two quantities up to second order in standard cosmological perturbation theory and find that they are correlated and can be linked via the kinematical backreaction of a spatially averaged universe model.

Infrared growth of geometrical fluctuations in inflationary spacetimes is investigated. The problem of gauge-invariant characterization of growth of perturbations, which is of interest also in other spacetimes such as black holes, is addressed by studying evolution of the lengths of curves in the geometry. These may either connect freely falling “satellites,” or wrap nontrivial cycles of geometries like the torus, and are also used in diffeomorphism-invariant constructions of two-point functions of field operators. For spacelike separations significantly exceeding the Hubble scale, no spacetime geodesic connects two events, but one may find geodesics constrained to lie within constant-time spatial slices. In inflationary geometries, metric perturbations produce significant and growing corrections to the lengths of such geodesics, as we show in both quantization on an inflating torus and in standard slow-roll inflation. These become large, signaling breakdown of a perturbative description of the geometry via such observables, and consistent with perturbative instability of de Sitter space. In particular, we show that the geodesic distance on constant time slices during inflation becomes nonperturbative a few e-folds after a given scale has left the horizon, by distances $\sim 1/H^3\sim RS$, obstructing use of such geodesics in constructing IR-safe observables based on the spatial geometry. We briefly discuss other possible measures of such geometrical fluctuations.

While the finite-temperature effective potential in a gauge theory is a gauge-dependent quantity, in several instances a first-order phase transition can be triggered by gauge-independent terms. A particularly interesting case occurs when the potential barrier separating the broken and symmetric vacua of a spontaneously broken symmetry is produced by tree-level terms in the potential. Here, we study this scenario in a simple Abelian Higgs model, for which the gauge-invariant potential is known, augmented with a singlet real scalar. We analyze the possible symmetry-breaking patterns in the model, and illustrate in which cases gauge artifacts are expected to manifest themselves most severely. We then show that gauge artifacts can be pronounced even in the presence of a relatively large, tree-level singlet-Higgs cubic interaction. When the transition is strongly first order, these artifacts, while present, are more subtle than in the generic situation.

Phase-plane stability analysis of a dynamical system describing the Universe as a two-fraction fluid containing baryonic dust and real virial gas quintessence is presented. Existence of a stable periodic solution experiencing inflationary periods is shown. A van der Waals quintessence model is revisited and cyclic Universe solution again found.

Axion as a coherently oscillating scalar field is known to behave as cold dark matter in all cosmologically relevant scales. For conventional axion mass with ${10}^{-5}\mathrm{eV}$, the axion reveals a characteristic damping behavior in the evolution of density perturbations on scales smaller than the Solar System size. The damping scale is inversely proportional to the square root of the axion mass. We show that the axion mass smaller than ${10}^{-24}\mathrm{eV}$ induces a significant damping in the baryonic density power spectrum in cosmologically relevant scales, thus deviating from the cold dark matter in the scale smaller than the axion Jeans scale. With such a small mass, however, our basic assumption about the coherently oscillating scalar field is broken in the early Universe. This problem is shared by other dark matter models based on the Bose-Einstein condensate and the ultralight scalar field. We introduce a simple model to avoid this problem by introducing evolving axion mass in the early Universe and present observational effects of a present-day low-mass axion on the baryon density power spectrum, the cosmic microwave background radiation temperature power spectrum, and the growth rate of baryon density perturbation. In our low-mass axion model, we have a characteristic small-scale cutoff in the baryon density power spectrum below the axion Jeans scale. The small-scale deviations from the cold dark matter model in both matter and cosmic microwave background radiation power spectra clearly differ from the ones expected in the cold dark matter model mixed with the massive neutrinos as a hot dark matter component.

In models of dark matter (DM) with Sommerfeld-enhanced annihilation, where the annihilation rate scales as the inverse velocity, $N$-body simulations of DM structure formation suggest that the local annihilation signal may be dominated by small, dense, cold subhalos. This contrasts with the usual assumption of a signal originating from the smooth DM halo, with much higher velocity dispersion. Accounting for local substructure modifies the parameter space for which Sommerfeld-enhanced annihilating DM can explain the PAMELA and Fermi excesses. Limits from the inner galaxy and the cosmic microwave background are weakened, without introducing new tension with substructure-dependent limits, such as from dwarf galaxies or isotropic gamma-ray studies. With substructure, previously excluded parameter regions with mediators of mass $\sim 1–200\mathrm{MeV}$ are now easily allowed. For $\mathcal{O}(\mathrm{MeV})$ mediators, subhalos in a specific range of host halo masses may be evaporated, further suppressing diffuse signals without affecting substructure in the Milky Way.

Times of arrival of high-energy neutrinos encode information about their sources. We demonstrate that the energy-dependence of the onset time of neutrino emission in advancing relativistic jets can be used to extract important information about the supernova/gamma-ray burst progenitor structure. We examine this energy and time dependence for different supernova and gamma-ray burst progenitors, including red and blue supergiants, helium cores, Wolf-Rayet stars, and chemically homogeneous stars, with a variety of masses and metallicities. For choked jets, we calculate the cutoff of observable neutrino energies depending on the radius at which the jet is stalled. Further, we exhibit how such energy and time dependence may be used to identify and differentiate between progenitors, with as few as one or two observed events, under favorable conditions.