We demonstrate separability of the Dirac equation in weakly charged rotating black hole spacetimes in all dimensions. The electromagnetic field of the black hole is described by a test field approximation, with the vector potential proportional to the primary Killing vector field. It is shown that the demonstrated separability can be intrinsically characterized by the existence of a complete set of mutually commuting first-order symmetry operators generated from the principal Killing-Yano tensor. The presented results generalize the results on integrability of charged particle motion and separability of charged scalar field studied in V. P. Frolov and P. Krtous [Phys. Rev. D 83, 024016 (2011)].

We investigate the possibility of explaining theoretically the galaxy rotation curves by a gravitational potential in total absence of dark matter. To this aim an analytic fourth-order theory of gravity, nonminimally coupled with a massive scalar field, is considered. Specifically, the interaction term is given by an analytic function $f(R,\varphi )$, where $R$ is the Ricci scalar and $\varphi$ is the scalar field. The gravitational potential is generated by a pointlike source and compared with the so-called Sanders’s potential that can be exactly reproduced in this case. This result means that the problem of dark matter in spiral galaxies could be fully addressed by revising general relativity at galactic scales and requiring further gravitational degrees of freedom instead of new material components that have not been found up to now.

We find static charged black hole solutions in nonlinear massive gravity. In the parameter space of two gravitational potential parameters $(\alpha ,\beta )$ we show that below the Compton wavelength the black hole solutions reduce to that of Reissner-Nordström via the Vainshtein mechanism in the weak-field limit. In the simplest case with $\alpha =\beta =0$ the solution exhibits the van Dam-Veltman-Zakharov discontinuity but ordinary general relativity is recovered deep inside the horizon due to the existence of electric charge, though this case is observationally excluded. For $\alpha \ne 0$ and $\beta =0$, the post-Newtonian parameter of the charged black hole evolves to that of general relativity via the Vainshtein mechanism within a macroscopic distance; however, a logarithmic correction to the metric factor of the time coordinate is obtained. When $\alpha$ and $\beta$ are both nonzero, there exist two branches of solutions depending on the positivity of $\beta$. When $\beta <0$, the strong coupling of the scalar graviton weakens gravity at distances smaller than the Vainshtein radius. However, when $\beta >0$ the metric factors exhibit only small corrections compared to the solutions obtained in general relativity, and under a particular choice of $\beta ={\alpha }^2/6$ the standard Reissner-Nordström-de Sitter solution is recovered.

We employ the superpotential technique for the reconstruction of cosmological models with a nonminimally coupled scalar field evolving on a spatially flat Friedmann-Robertson-Walker background. The key point in this method is that the Hubble parameter is considered as a function of the scalar field, and this allows one to reconstruct the scalar field potential and determine the dynamics of the field itself, without a priori fixing the Hubble parameter as a function of time or of the scale factor. The scalar field potentials that lead to de Sitter or asymptotic de Sitter solutions, and those that reproduce the cosmological evolution given by Einstein-Hilbert action plus a barotropic perfect fluid, have been obtained.

The analogy between the Skyrme and Higgs fields leads to the conjecture that all fermions are skyrmions and thus always carry conserved quantum numbers, which are identified with baryon or lepton quantum numbers. This connection between spin and quantum numbers, which parallels the connection between spin and statistics due to the Pauli principle, may explain why supersymmetry has not been observed. Creation of sparticles at higher than present energies due to a breakdown of the Skyrme mechanism might imply the violation of the exclusion principle.

Multi-Higgs production provides a phenomenologically clear window to the electroweak symmetry-breaking sector. We perform a comprehensive and comparative analysis of new electroweak physics effects in di-Higgs and $\mathrm{\text{di}}\mathrm{\text{−}}\mathrm{\text{Higgs}}+\mathrm{\text{jet}}$ production. In particular, we discuss resonant di-Higgs phenomenology, which arises in the Higgs portal model and in the minimal supersymmetric Standard Model at small $\tan \beta$, and nonresonant new-physics contributions to di-Higgs production in models where the newly discovered Higgs candidate is interpreted as a pseudo-Nambu-Goldstone boson. We show that, for all these scenarios, a measurement of the di-Higgs and $\mathrm{\text{di}}\mathrm{\text{−}}\mathrm{\text{Higgs}}+\mathrm{\text{jet}}$ final states provides an accessible and elaborate handle to understand electroweak symmetry breaking in great detail.

An equivariantly gauge-fixed non-Abelian gauge theory is a theory in which a coset of the gauge group, not containing the maximal Abelian subgroup, is gauge fixed. Such theories are nonperturbatively well defined. In a finite volume, the equivariant Becchi-Rouet-Stora-Tyutin symmetry guarantees that expectation values of gauge-invariant operators are equal to their values in the unfixed theory. However, turning on a small breaking of this symmetry, and turning it off after the thermodynamic limit has been taken, can in principle reveal new phases. In this paper we use a combination of strong-coupling and mean-field techniques to study an $SU(2)$ Yang-Mills theory equivariantly gauge fixed to a $U(1)$ subgroup. We find evidence for the existence of a new phase in which two of the gluons becomes massive while the third one stays massless, resembling the broken phase of an $SU(2)$ theory with an adjoint Higgs field. The difference is that here this phase occurs in an asymptotically free theory.

The existence and the properties of self-bound quark matter in the Nambu-Jona-Lasinio model at zero temperature are investigated in the mean-field approximation, focusing on inhomogeneous structures with one-dimensional spatial modulations. It is found that the most stable homogeneous solutions which have previously been interpreted as schematic quark droplets are unstable against the formation of a one-dimensional lattice of domain-wall solitons. The solitons repel each other, so that the minimal energy per quark is realized in the single-soliton limit. The properties of the solitons and their interactions are discussed in detail, and the effect of vector interactions is estimated. The results may be relevant for the dynamics of expanding quark matter.

We study a finite temperature two-loop resummed effective potential in the Abelian gauge theory. A tractable calculation scheme without using a high-temperature expansion is devised. We apply it to the Abelian-Higgs model and its extension to a minimal supersymmetric standard model-like model and study the thermal phase transition. It is shown that our scheme improves the previous results about 10% in the quantities relevant to the phase transition, and its impacts on bubble dynamics could be even more sizable. It still holds that the stop-stop-gluon sunset diagram enhances the strength of the first-order phase transition even without the high-temperature expansion.

The decay modes $\overline{B}\to D^{(*)}\tau {\overline{\nu }}_{\tau }$ are sensitive to charged scalar effects, such as the charged Higgs effects. In this paper we suggest a method to determine their effects by using the ratio of branching fractions and forward-backward asymmetries. In particular, forward-backward asymmetries on $\overline{B}\to D^{(*)}\tau (\to \pi {\nu }_{\tau }){\overline{\nu }}_{\tau }$, $\overline{B}\to D^{(*)}\tau (\to \rho {\nu }_{\tau }){\overline{\nu }}_{\tau }$, and $\overline{B}\to D^{(*)}\tau (\to a_1{\nu }_{\tau }){\overline{\nu }}_{\tau }$ play an important role, which differentiates the Standard Model from other New Physics scenarios.

We search for the M1 radiative transition $\psi (3686)\to \gamma {\eta }_c(2S)$ by reconstructing the exclusive ${\eta }_c(2S)\to K_S^0{K}^{\pm }{\pi }^{\mp }{\pi }^{+}{\pi }^{-}$ decay using $1.06\times {10}^8$ $\psi (3686)$ events collected with the BESIII detector. The signal is observed with a statistical significance of greater than 4 standard deviations. The measured mass of the ${\eta }_c(2S)$ is $3646.9\pm 1.6(\mathrm{stat})\pm 3.6(\mathrm{syst})\mathrm{MeV}/c^2$, and the width is $9.9\pm 4.8(\mathrm{stat})\pm 2.9(\mathrm{syst})\mathrm{MeV}/c^2$. The product branching fraction is measured to be $\mathcal{B}(\psi (3686)\to \gamma {\eta }_c(2S))\times \mathcal{B}({\eta }_c(2S)\to K_S^0{K}^{\pm }{\pi }^{\mp }{\pi }^{+}{\pi }^{-})=(7.03\pm 2.10(\mathrm{stat})\pm 0.70(\mathrm{syst}))\times {10}^{-6}$. This measurement complements a previous BESIII measurement of $\psi (3686)\to \gamma {\eta }_c(2S)$ with ${\eta }_c(2S)\to K_S^0{K}^{\pm }{\pi }^{\mp }$ and $K^{+}{K}^{-}{\pi }^0$.

Using $1.8{\mathrm{fb}}^{-1}$ of $pp$ collisions at a center-of-mass energy of 7 TeV recorded by the ATLAS detector at the Large Hadron Collider, we present measurements of the production cross sections of $\mathit{{\rm Y}}(1\mathrm{S},2\mathrm{S},3\mathrm{S})$ mesons. $\mathit{{\rm Y}}$ mesons are reconstructed using the dimuon decay mode. Total production cross sections for $p_{\mathrm{T}}<70\mathrm{GeV}$ and in the rapidity interval $|y^{\mathit{{\rm Y}}}|<2.25$ are measured to be, $8.01\pm 0.02\pm 0.36\pm 0.31\mathrm{nb}$, $2.05\pm 0.01\pm 0.12\pm 0.08\mathrm{nb}$, and $0.92\pm 0.01\pm 0.07\pm 0.04\mathrm{nb}$, respectively, with uncertainties separated into statistical, systematic, and luminosity measurement effects. In addition, differential cross section times dimuon branching fractions for $\mathit{{\rm Y}}(1\mathrm{S})$, $\mathit{{\rm Y}}(2\mathrm{S})$, and $\mathit{{\rm Y}}(3\mathrm{S})$ as a function of $\mathit{{\rm Y}}$ transverse momentum $p_{\mathrm{T}}$ and rapidity are presented. These cross sections are obtained assuming unpolarized production. If the production polarization is fully transverse or longitudinal with no azimuthal dependence in the helicity frame, the cross section may vary by approximately $\pm 20\%$. If a nontrivial azimuthal dependence is considered, integrated cross sections may be significantly enhanced by a factor of 2 or more. We compare our results to several theoretical models of $\mathit{{\rm Y}}$ meson production, finding that none provide an accurate description of our data over the full range of $\mathit{{\rm Y}}$ transverse momenta accessible with this data set.

We present a detailed report of the method, setup, analysis, and results of a precision measurement of the positive muon lifetime. The experiment was conducted at the Paul Scherrer Institute using a time-structured, nearly 100% polarized surface muon beam and a segmented, fast-timing plastic scintillator array. The measurement employed two target arrangements: a magnetized ferromagnetic target with a $\sim 4\mathrm{kG}$ internal magnetic field and a crystal quartz target in a 130 G external magnetic field. Approximately $1.6\times {10}^{12}$ positrons were accumulated and together the data yield a muon lifetime of ${\tau }_{\mu }(\mathrm{\text{MuLan}})=2196980.3(2.2)\mathrm{ps}$ (1.0 ppm), 30 times more precise than previous generations of lifetime experiments. The lifetime measurement yields the most accurate value of the Fermi constant $G_F(\mathrm{\text{MuLan}})=1.1663787(6)\times {10}^{-5}{\mathrm{GeV}}^{-2}$ (0.5 ppm). It also enables new precision studies of weak interactions via lifetime measurements of muonic atoms.

A generic search for anomalous production of events with at least three charged leptons is presented. The search uses a $pp$-collision data sample at a center-of-mass energy of $\sqrt{s}=7\mathrm{TeV}$ corresponding to $4.6{\mathrm{fb}}^{-1}$ of integrated luminosity collected in 2011 by the ATLAS detector at the CERN Large Hadron Collider. Events are required to contain at least two electrons or muons, while the third lepton may either be an additional electron or muon, or a hadronically decaying tau lepton. Events are categorized by the presence or absence of a reconstructed tau-lepton or $Z$-boson candidate decaying to leptons. No significant excess above backgrounds expected from Standard Model processes is observed. Results are presented as upper limits on event yields from non-Standard-Model processes producing at least three prompt, isolated leptons, given as functions of lower bounds on several kinematic variables. Fiducial efficiencies for model testing are also provided. The use of the results is illustrated by setting upper limits on the production of doubly charged Higgs bosons decaying to same-sign lepton pairs.

We point out that theories of cosmological acceleration which have equation of state, $w$, such that $1+w$ is small but positive may still secretly violate the null energy condition. This violation implies the existence of observers for whom the background has infinitely negative energy densities, despite the fact that the perturbations are free of ghosts and gradient instabilities.

It was shown in Dey and Roy [J. High Energy Phys. 06 (2012) 129] that the near-horizon limit of the $1/4$ Bogomol’nyi-Prasad-Sommerfield, threshold $\mathrm{F}\mathrm{\text{−}}\mathrm{D}p$ (for $0\le p\le 5$, $p\ne 4$) bound-state solutions of type-II string theories give rise to space-time metrics endowed with Lifshitz scaling along with hyperscaling violation. Here we compute the holographic entanglement entropy of this system for all $p\ne 4$ (for $p=4$ the space-time has ${\mathrm{AdS}}_2$ structure). For $p=3$, 5, we get the expected area-law behavior of the entanglement entropy. For $p=0$, 1, the entanglement entropy has new area-law violations and exhibits behavior which is in between the linear and logarithmic behaviors. For $p=2$, we get a logarithmic violation of the area law. We also compute the entanglement entropy at finite temperature and show that as the temperature rises, the entanglement entropy makes a crossover to the thermal entropy of the system. We thus obtain the string-theoretic realization of the holographic entanglement entropy and its various aspects, which were noted earlier for a generic metric with hyperscaling violation.

In this paper, we compare dispersions of a scalar field in Euclidean quantum gravity with stochastic inflation. We use Einstein gravity and a minimally coupled scalar field with a quadratic potential. We restrict our attention to small mass and small field cases. In the Euclidean approach, we introduce the ground state wave function which is approximated by instantons. We used a numerical technique to find instantons that satisfy classicality. In the stochastic approach, we introduce the probability distribution of Hubble patches that can be approximated by locally homogeneous universes down to a smoothing scale. We assume that the ground state wave function should correspond to the stationary state of the probability distribution of the stochastic Universe. By comparing the dispersion of both approaches, we conclude three main results. (1) For a statistical distribution with a certain value, we can find a corresponding instanton in the Euclidean side, and it should be a complex-valued instanton. (2) The size of the Universe of the Euclidean approach corresponds to the smoothing scale of the stochastic side; the Universe is homogeneous up to the Euclidean instanton. (3) In addition, as the mass increases up to a critical value, both approaches break at the same time. Hence, generation of classical inhomogeneity in the stochastic approach and the instability of classicality in the Euclidean approach are related.

The volume fractions of vacua in an eternally inflating multiverse are described by a coarse-grain rate equation, which accounts for volume expansion and vacuum transitions via bubble formation. We generalize the rate equation to account for bubble collisions, including the possibility of classical transitions. Classical transitions can modify the details of the hierarchical structure among the volume fractions, with potential implications for the staggering and Boltzmann-brain issues. Whether or not our vacuum is likely to have been established by a classical transition depends on the detailed relationships among transition rates in the landscape.

We consider mesons composed of light and heavy quarks and discuss the construction of the corresponding meson wave functions in soft-wall AdS/QCD. We specifically take care that constraints imposed by chiral symmetry breaking and by the heavy quark limit are fulfilled. The main results are (i) the wave functions of light mesons have a nontrivial dependence on the current quark mass, which gives rise to a mass spectrum consistent with the one including explicit breaking of chiral symmetry; (ii) the wave functions of heavy-light mesons generate their correct mass spectrum, the mass splittings of vector and pseudoscalar states, and the correct scaling of leptonic decay constants $f_{Q\overline{q}}\sim 1/\sqrt{m_Q}$; (iii) the wave functions of heavy quarkonia produce their correct mass spectrum and lead to a scaling behavior of the leptonic decay constants $f_{Q\overline{Q}}\sim \sqrt{m_Q}$ and $f_{c\overline{b}}\sim m_c/\sqrt{m_b}$ at $m_c\ll m_b$, consistent with potential models and QCD sum rules.

We analyze the constrained minimal supersymmetric standard model with $\mu >0$ supplemented by a generalized “asymptotic” Yukawa coupling quasiunification condition, which allows an acceptable $b$-quark mass. We impose constraints from the cold dark matter abundance in the Universe, $B$ physics, and the mass $m_h$ of the lightest neutral $CP$-even Higgs boson. We find that, in contrast to previous results with a more restrictive Yukawa quasiunification condition, the lightest neutralino $\tilde{\chi }$ can act as a cold dark matter candidate in a relatively wide parameter range. In this range, the lightest neutralino relic abundance is drastically reduced mainly by stau-antistau coannihilations and, thus, the upper bound on this abundance from cold dark matter considerations becomes compatible with the recent data on the branching ratio of $B_s\to {\mu }^{+}{\mu }^{-}$. Also, $m_h\simeq (125–126)\mathrm{GeV}$, favored by LHC, can be easily accommodated. The mass of $\tilde{\chi }$, though, comes out large ($\sim 1\mathrm{TeV}$).