Motivated by the string corrections on the gravity and electrodynamics sides, we consider a quadratic Maxwell invariant term as a correction of the Maxwell Lagrangian to obtain exact solutions of higher dimensional topological black holes in Gauss-Bonnet gravity. We first investigate the asymptotically flat solutions and obtain conserved and thermodynamic quantities which satisfy the first law of thermodynamics. We also analyze thermodynamic stability of the solutions by calculating the heat capacity and the Hessian matrix. Then, we focus on horizon-flat solutions with an anti–de Sitter (AdS) asymptote and produce a rotating spacetime with a suitable transformation. In addition, we calculate the conserved and thermodynamic quantities for asymptotically AdS black branes which satisfy the first law of thermodynamics. Finally, we perform thermodynamic instability criterion to investigate the effects of nonlinear electrodynamics in canonical and grand canonical ensembles.

The baryon density enhancement in cosmic string wakes leads to a stronger coupling of the spin temperature to the gas kinetic temperate inside these string wakes than in the intergalactic medium (IGM). The Wouthuysen-Field (WF) effect has the potential to enhance this coupling to such an extent that it may result in the strongest and cleanest cosmic string signature in the currently planned radio telescope projects. Here we consider this enhancement under the assumption that x-ray heating is not significant. We show that the size of this effect in a cosmic string wake leads to a brightness temperature at least two times more negative than in the surrounding IGM. If the SCI-HI [T. C. Voytek et al., Astrophys. J. 782, L9 (2014), J. B. Peterson et al., arXiv:1409.2774] or EDGES [J. D. Bowman and A. E. E. Rogers Nature (London) 468, 796 (2010), J. D. Bowman et al., Astrophys. J. 676, 1 (2008)] experiments confirm a WF absorption trough in the cosmic gas, then cosmic string wakes should appear clearly in 21 cm redshift surveys of $z=10$ to 30.

We investigate the purely spatial Lagrangian coordinate transformation from the Lagrangian to the basic Eulerian frame. We demonstrate three techniques for extracting the relativistic displacement field from a given solution in the Lagrangian frame. These techniques are (a) from defining a local set of Eulerian coordinates embedded into the Lagrangian frame; (b) from performing a specific gauge transformation; and (c) from a fully nonperturbative approach based on the Arnowitt-Deser-Misner (ADM) split. The latter approach shows that this decomposition is not tied to a specific perturbative formulation for the solution of the Einstein equations. Rather, it can be defined at the level of the nonperturbative coordinate change from the Lagrangian to the Eulerian description. Studying such different techniques is useful because it allows us to compare and develop further the various approximation techniques available in the Lagrangian formulation. We find that one has to solve the gravitational wave equation in the relativistic analysis, otherwise the corresponding Newtonian limit will necessarily contain spurious nonpropagating tensor artifacts at second order in the Eulerian frame. We also derive the magnetic part of the Weyl tensor in the Lagrangian frame, and find that it is not only excited by gravitational waves but also by tensor perturbations which are induced through the nonlinear frame dragging. We apply our findings to calculate for the first time the relativistic displacement field, up to second order, for a $\mathrm{\Lambda }\mathrm{CDM}$ Universe in the presence of a local primordial non-Gaussian component. Finally, we also comment on recent claims about whether mass conservation in the Lagrangian frame is violated.

We propose an association between the phase-space mixing level of a self-gravitating system and the indistinguishability of its constituents (stars or dark matter particles). This represents a refinement in the study of systems exhibiting incomplete violent relaxation. Within a combinatorial analysis similar to that of Lynden-Bell, we make use of this association to obtain a distribution function that deviates from the Maxwell-Boltzmann distribution, increasing its slope for high energies. Considering the smallness of the occupation numbers for large distances from the center of the system, we apply a correction to Stirling’s approximation which increases the distribution slope also for low energies. The distribution function thus obtained presents some resemblance to the “S” shape of distributions associated with cuspy density profiles (as compared to the distribution function obtained from the Einasto profile), although it is not quite able to produce sharp cusps. We also argue how the association between mixing level and indistinguishability can provide a physical meaning to the assumption of particle-permutation symmetry in the N-particle distribution function, when it is used to derive the one-particle Vlasov equation, which raises doubts about the validity of this equation during violent relaxation.

We present a simple cosmological model in which a single, nonminimally coupled scalar field with a quartic potential is responsible for both inflation at early times and acceleration at late times. Little or no fine tuning is needed to explain why the present density of dark energy is comparable to that of pressureless matter. Dark energy is identified with the potential of the scalar field, which is sourced by the trace of the energy-momentum tensor. This becomes significant when matter has decoupled from radiation and become fully nonrelativistic, so that $\varphi \propto {\rho }_m^{1/3}\propto {\rho }_{m,0}^{1/3}(a_0/a)\sim (10^{-120}{)}^{1/3}(10^{10})\sim 10^{-30}$ and $V\sim {\varphi }^4\sim 10^{-120}$ in Planck units, as observed.

We perform numerical evolutions of cosmological scenarios using a standard general relativistic code in spherical symmetry. We concentrate on two different situations: initial matter distributions that are homogeneous and isotropic, and perturbations to those that respect the spherical symmetry. As matter models we consider the case of a pressureless perfect fluid, i.e. dust, and the case of a real massive scalar field oscillating around the minimum of the potential. Both types of matter have been considered as possible dark matter candidates in the cosmology literature, dust being closely related to the standard cold dark matter paradigm. We confirm that in the linear regime the perturbations associated with these types of matter grow in essentially the same way, the main difference being that in the case of a scalar field the dynamics introduce a cutoff in the power spectrum of the density perturbations at scales comparable with the Compton wavelength of the field. We also follow the evolutions well beyond the linear regime showing that both models are able to form structure. In particular we find that, once in the nonlinear regime, perturbations collapse faster in a universe dominated by dust. This is expected to delay the formation of the first structures in the scalar field dark matter scenario with respect to the standard cold dark matter one.

To identify what replaces the key notion of black hole horizon when working with theories which break Lorentz invariance at high energy, we study the modes responsible for the Hawking effect in the presence of high frequency dispersion. We show that they are regularized across the horizon over a short length which only depends on the scale of dispersion and the surface gravity. Moreover, outside this width, short and long wavelength modes no longer mix. These results can be used to show that the spectrum is hardly modified by dispersion as long as the background geometry does not vary significantly over this length. For relevant frequencies, the regularization differs from the usual WKB resolution of wave singularity near a turning point.

Nonperturbative renormalization and explicit construction of the effective potential of the Hartree approximation of the two-particle-irreducible formalism are carried out in an inhomogeneous field configuration describing a uniform superfluid. Based on the eariler article [G. Fejős et al., Nucl. Phys. A803, 115 (2008)], we clarify certain aspects of renormalizability corresponding to the findings of [M. G. Alford et al., Phys. Rev. D 89, 085005 (2014)]. We show that renormalizability of the approximation can be ensured by regularization schemes respecting Lorentz and translation invariance. Elimination of nonconventional superflow-dependent divergences is presented in detail, together with a discussion on the finite-temperature treatment.

We present a treatment of the high energy scattering of dark Dirac fermions from nuclei, mediated by the exchange of a light vector boson. The dark fermions are produced by proton-nucleus interactions in a fixed target and, after traversing shielding that screens out strongly interacting products, appear similarly to neutrino neutral current scattering in a detector. Using the Fermilab experiment E613 as an example, we place limits on a secluded dark matter scenario. Visible scattering in the detector includes both the familiar regime of large momentum transfer to the nucleus ($Q^2$) described by deeply inelastic scattering, as well as small $Q^2$ kinematics described by the exchanged vector mediator fluctuating into a quark-antiquark pair whose interaction with the nucleus is described by a saturation model. We find that the improved description of the low $Q^2$ scattering leads to important corrections, resulting in more robust constraints in a regime where a description entirely in terms of deeply inelastic scattering cannot be trusted.

Direct searches for lepton flavor-violating Higgs boson decays in the $\tau \mu$ channel have recently been reported by the CMS Collaboration. The results display a slight excess of signal events with a significance of $2.5\sigma$, which translates into a branching ratio of about 1%. By interpreting these findings as a hint for beyond the standard model physics, we show that the Type-III 2HDM is capable of reproducing such a signal while at the same time satisfying from below boundedness of the scalar potential, perturbativity, electroweak precision data, measured Higgs standard decay modes, and low-energy lepton flavor-violating constraints. We have found that the allowed signal strength ranges for the $b\overline{b}$, $W{W}^{*}$, and $Z{Z}^{*}$ standard channels shrink as soon as $\mathrm{BR}(h\to \tau \mu )\sim 1\%$ is enforced. Thus, we point out that if the excess persists, improved measurements of these channels may be used to test our Type-III 2HDM scenario.

We first formulate, in the framework of the effective Lagrangian, the general form of the effective interactions of the lightest Higgs boson $h$ and a heavier neutral Higgs boson $H$ in a multi-Higgs system taking account of the Higgs mixing effect. We regard $h$ as the discovered Higgs boson which has been shown to be consistent with the standard model Higgs boson. The obtained effective interactions contain extra parameters reflecting the Higgs mixing effect. Next, we study the constraints on the anomalous coupling constants of $H$ from both the requirement of the unitarity of the $S$ matrix and the exclusion bounds on the standard model Higgs boson obtained from the experimental data at the 7–8 TeV LHC. From this we obtain the available range of the anomalous coupling constants of $H$, with which $H$ is not excluded by the yet known theoretical and experimental constraints. We then study the signatures of $H$ at the 14 TeV LHC. In this paper, we suggest taking weak-boson scattering and $pp\to V{H}^{*}\to VVV$ as sensitive processes for probing $H$ model independently at the 14 TeV LHC. We take several examples with the anomalous $HVV$ coupling constants in the available ranges to do the numerical study. A full tree-level calculation at the hadron level is given with signals and backgrounds carefully calculated. We impose a series of proper kinematic cuts to effectively suppress the backgrounds. It is shown that, in both the $VV$ scattering and the $pp\to V{H}^{*}\to VVV$ processes, the $H$ boson can be discovered from the invariant mass distributions of the final state particles with reasonable integrated luminosity. Especially, in the $pp\to V{H}^{*}\to VVV$ process, the invariant mass distribution of the final state jets can show a clear resonance peak of $H$. Finally, we propose several physical observables from which the values of the anomalous coupling constants $f_W$ and $f_{WW}$ can be measured experimentally.

We calculate the anomalous dimensions of the next-to-leading-order dijet operators in soft-collinear effective theory (SCET). We use a formulation of SCET where the Lagrangian is multiple copies of QCD and the interactions between sectors occur through light-like Wilson lines in external currents. We introduce a small gluon mass to regulate the infrared divergences of the individual loop diagrams in order to properly extract the ultraviolet divergences. We discuss this choice of infrared regulator and contrast it with the $\delta$ regulator. Our results can be used to increase the theoretical precision of the thrust distribution.

We present numerical results of electric conductivity ${\sigma }_{\text{el}}$ of a fluid obtained solving the relativistic transport Boltzmann equation in a box with periodic boundary conditions. We compute ${\sigma }_{\text{el}}$ using two methods: the definition itself, i.e., applying an external electric field, and the evaluation of the Green-Kubo relation based on the time evolution of the current-current correlator. We find a very good agreement between the two methods. We also compare numerical results with analytic formulas in relaxation time approximation (RTA) where the relaxation time for ${\sigma }_{\text{el}}$ is determined by the transport cross section ${\sigma }_{\text{tr}}$, i.e., the differential cross section weighted with the collisional momentum transfer. We investigate the electric conductivity dependence on the microscopic details of the two-body scatterings: isotropic and anisotropic cross section as well as massless and massive particles. We find that the RTA underestimates considerably ${\sigma }_{\text{el}}$; for example, at screening masses $m_D\sim T$, such underestimation can be as large as a factor of 2. Furthermore, we study a more realistic case for a quark-gluon system (QGP) considering both a quasiparticle model tuned to lattice QCD (lQCD) thermodynamics, as well as the case of a perturbative QCD (pQCD) gas with running coupling. Also, for these cases more directly related to the description of the QGP system, we find that the RTA significantly underestimates the ${\sigma }_{\text{el}}$ by about 60%–80%.

The baryon vector current is computed at one-loop order in large-$N_c$ baryon chiral perturbation theory, where $N_c$ is the number of colors. Loop graphs with octet and decuplet intermediate states are systematically incorporated into the analysis and the effects of the decuplet-octet mass difference and $SU(3)$ flavor symmetry breaking are accounted for, giving the full result to order $\mathcal{O}(p^2)$ in the chiral expansion. There are large-$N_c$ cancellations between different one-loop graphs as a consequence of the large-$N_c$ spin-flavor symmetry of QCD baryons. The results are compared against the available experimental data through several fits in order to extract information about the unknown parameters. The large-$N_c$ baryon chiral perturbation theory predictions are in very good agreement both with the expectations from the $1/N_c$ expansion and with the experimental data. The effect of $SU(3)$ flavor symmetry breaking for the $|\mathrm{\Delta }S|=1$ vector current form factors $f_1(0)$ results in a reduction by a few percent with respect to the corresponding $SU(3)$ symmetric values.

We consider a mechanism for neutrino mass generation, based on a local $B-L$ extension of the standard model, which becomes a linear seesaw regime for light neutrinos after spontaneous symmetry breaking. The spectrum of extra particles includes heavy neutrinos with masses near the TeV scale and a heavy $Z^{\prime }$ boson, as well as three extra neutral scalars and a charged scalar pair. We study the production and decays of these heavy particles at the LHC. $Z^{\prime }$ will decay mainly into heavy neutrino pairs or charged lepton pairs, similar to other low scale seesaw scenarios with local $B-L$, while the phenomenology of the extra scalars is what distinguishes the linear seesaw from the previous models. One of the neutral scalars is produced by $Z^{\prime }{Z}^{\prime }$ fusion and decays mainly into vector boson pairs, the other two neutral scalars are less visible as they decay only into heavy or light neutrino pairs, and finally the charged scalars will decay mainly into charged leptons and missing energy.

The muon and tauon light-by-light scattering contributions to hyperfine splitting in muonium are calculated. These results conclude the calculation of all hard three-loop contributions to hyperfine splitting generated by the graphs with closed fermion loops. We discuss the special role that the lepton anomalous magnetic moments play in these calculations. The full result for all three-loop radiative-recoil corrections to hyperfine splitting generated by the graphs with closed lepton loops is presented.

The muon decay parameter ${\xi }^{\prime \prime }$ has been determined in a measurement of the longitudinal polarization of positrons emitted from polarized and depolarized muons. The result, ${\xi }^{\prime \prime }=0.981\pm 0.045_{\text{stat}}\pm 0.003_{\text{syst}}$, is consistent with the Standard Model prediction of unity, and provides an order of magnitude improvement in the relative precision of this parameter. This value sets new constraints on exotic couplings beyond the dominant $V\text{−}A$ description of the leptonic weak interaction.

By using a simple thermodynamical method, we confirm the finding of Chavanis and Harko that stable Bose-Einstein condensate stars can form. However, by using a thermodynamically consistent boson equation of state, we obtain a less massive Bose-Einstein condensate star compared to the one predicted by Chavanis and Harko. We also obtain that the maximum mass of a boson star is insensitive to the change of matter temperature. However, the mass of a boson star with relatively large radius depends significantly on the temperature of the boson matter.

We show how to construct the familiar heterotic NS5 brane as a topological soliton in a supercritical version of heterotic string theory. Closed string tachyon condensation removes the extra dimensions, leaving the NS5 in ten dimensions, in a process highly reminiscent of the K-theoretical description of type II D-branes, but linking nontrivial gauge bundles and geometry. This establishes a new kind of equivalence between gravitational and gauge configurations, reminiscent of the gauge/geometry correspondence. We also use the K-theory description to build other heterotic branes as solitons of closed string tachyons. The construction requires a modification of the anomalous Bianchi identity for $H_3$ in supercritical heterotic string theory. We give various proofs for the existence of this modification.

We construct the anti–de Sitter-plane wave solutions of generic gravity theory built on the arbitrary powers of the Riemann tensor and its derivatives in analogy with the $pp$-wave solutions. In constructing the wave solutions of the generic theory, we show that the most general two-tensor built from the Riemann tensor and its derivatives can be written in terms of the traceless Ricci tensor. Quadratic gravity theory plays a major role; therefore, we revisit the wave solutions in this theory. As examples of our general formalism, we work out the six-dimensional conformal gravity and its nonconformal deformation as well as the tricritical gravity, the Lanczos-Lovelock theory, and string-generated cubic curvature theory.