In this paper we calculate the holographic entanglement entropy in the presence of a conformal interface for a geometric configuration in which the entangling region $\mathcal{A}$ lies on one side of the interface. For the supersymmetric Janus solution we find exact agreement between the holographic and conformal field theory calculation of the entanglement entropy.

We investigate a Lorentz-violating chiral model composed of two fermions, a complex scalar field, and a gauge field. We show that, by conveniently adjusting the parameters of the model, it is possible to generate an unambiguous Carroll-Field-Jackiw term and, at the same time, provide the cancellation of the chiral anomaly. The renormalizability of the model is investigated, and it is shown that the same counterterms needed in the symmetric phase also renormalize the model with broken symmetry.

Abelian gauge theory in $d\ne 4$ spacetime dimensions is an example of a scale-invariant theory which does not possess conformal symmetry—the special conformal transformation (SCT) explicitly breaks the gauge invariance of the theory. In this work, we construct a nonlocal gauge-invariant extension of the SCT, which is compatible with the BRST formalism and defines a new symmetry of the physical Hilbert space of the Maxwell theory for any dimension $d\ge 3$. We prove the invariance of the Maxwell theory in $d\ge 3$ by explicitly showing that the gauge-invariant two-point correlation functions, the action, and the classical equation of motion are unchanged under such a transformation.

We conjecture a novel generalized second law that can be applied in cosmology, regardless of whether an event horizon is present: the generalized entropy increases monotonically outside of certain hypersurfaces we call past Q-screens. A past Q-screen is foliated by surfaces whose generalized entropy (sum of area and entanglement entropy) is stationary along one future null direction and increasing along the other. We prove that our generalized second law holds in spacetimes obeying the quantum focusing conjecture. An analogous law applies to future Q-screens, which appear inside evaporating black holes and in collapsing regions.

We investigate the motion of test particles in the gravitational field of a static naked singularity generated by a mass distribution with a quadrupole moment. We use the quadrupole metric ($q$ metric) which is the simplest generalization of the Schwarzschild metric with a quadrupole parameter. We study the influence of the quadrupole on the motion of massive test particles and photons and show that the behavior of the geodesics can drastically depend on the values of the quadrupole parameter. In particular, we prove explicitly that the perihelion distance depends on the value of the quadrupole. Moreover, we show that an accretion disk on the equatorial plane of the quadrupole source can be either continuous or discrete, depending on the value of the quadrupole. The inner radius of the disk can be used in certain cases to determine the value of the quadrupole parameter. The case of a discrete accretion is interpreted as due to the presence of repulsive gravity generated by the naked singularity. Radial geodesics are also investigated and compared with the Schwarzschild counterparts.

At second order in perturbation theory, the $r$-modes of uniformly rotating stars include an axisymmetric part that can be identified with differential rotation of the background star. If one does not include radiation reaction, the differential rotation is constant in time and has been computed by Sá. It has a gauge dependence associated with the family of time-independent perturbations that add differential rotation to the unperturbed equilibrium star: For stars with a barotropic equation of state, one can add to the time-independent second-order solution arbitrary differential rotation that is stratified on cylinders (that is a function of distance $\varpi$ to the axis of rotation). We show here that the gravitational radiation-reaction force that drives the $r$-mode instability removes this gauge freedom; the exponentially growing differential rotation of the unstable second-order $r$-mode is unique. We derive a general expression for this rotation law for Newtonian models and evaluate it explicitly for slowly rotating models with polytropic equations of state.

We explore the critical behavior of ($n+1$)-dimensional topological Born-Infeld-dilaton black holes in an extended phase space. We treat the cosmological constant and the Born-Infeld (BI) parameter as the thermodynamic pressure and BI vacuum polarization which can vary. We obtain thermodynamic quantities of the system such as pressure, temperature, Gibbs free energy, and investigate the behavior of these quantities. We also study the analogy of the van der Waals liquid-gas system with the Born-Infeld-dilaton black holes in canonical ensemble in which we can treat the black hole charge as a fixed external parameter. Moreover, we show that the critical values of pressure, temperature and volume are physical provided the coupling constant of dilaton gravity is less than 1 and the horizon is sphere. Finally, we calculate the critical exponents and show that although thermodynamic quantities depend on the dilaton coupling constant, BI parameter and the dimension of the spacetime, they are universal and are independent of metric parameters.

We consider Palatini $f(R,T)$ gravity models, similar to those introduced by Harko et al. (2012), where the gravitational Lagrangian is given by an arbitrary function of the curvature scalar $R$ and of the trace of the energy-momentum tensor $T$. Interior spherical static solutions are studied considering the model of matter given by a perfect fluid configuration and a polytropic equation of state. We analyze the curvature singularities found previously for Palatini $f(R)$ gravity and discuss the possibility to remove them in some particular $f(R,T)$ models. We show that it is possible to construct a restricted family of models for which these singularities are not present.

We discuss simple models which predict the existence of significant gamma-ray fluxes from dark matter annihilation. In this context the dark matter candidate is a Majorana fermion with velocity-suppressed tree-level annihilation into standard model fermions but unsuppressed annihilation into photons. These gamma lines can easily be distinguished from the continuum and provide a possibility to test these models.

We investigate the collapse of clusters of weakly interacting massive particles (WIMPs) in the core of a Sun-like star and the possible formation of mini-black holes and the emission of gravitational waves. When the number of WIMPs is small, thermal pressure balances the WIMP cluster’s self gravity. If the number of WIMPs is larger than a critical number, thermal pressure cannot balance gravity and the cluster contracts. If WIMPs are collisionless and bosonic, the cluster collapses directly to form a mini-black hole. For fermionic WIMPs, the cluster contracts until it is sustained by Fermi pressure, forming a small compact object. If the fermionic WIMP mass is smaller than $4\times {10}^2\mathrm{GeV}$, the radius of the compact object is larger than its Schwarzschild radius and Fermi pressure temporally sustains its self-gravity, halting the formation of a black hole. If the fermionic WIMP mass is larger than $4\times {10}^2\mathrm{GeV}$, the radius is smaller than its Schwarzschild radius and the compact object becomes a mini-black hole. If the WIMP mass is 1 TeV, the size of the black hole will be approximately 2.5 cm and ultra high frequency gravitational waves will be emitted during black hole formation. The central frequency $f_c$ of ringdown gravitational waves emitted from the black hole will be approximately 2 GHz. To detect the ringdown gravitational waves, the detector’s noise must be below $\sqrt{S_h(f_c)}\approx 10^{-30}/\sqrt{\mathrm{Hz}}$.

Motivated by recent intensive experimental efforts on searching for neutrinoless double-beta decays, we perform a detailed analysis of the physics potential of the experiments based on ${}^{76}\mathrm{Ge}$. Assuming no signals, current and future experiments could place a 90% lower limit on the half life $T_{1/2}^{0\nu }\gtrsim 4\times {10}^{26}\mathrm{yr}$ and $T_{1/2}^{0\nu }\gtrsim 7\times {10}^{27}\mathrm{yr}$, respectively. Then, how to report an evidence for neutrinoless double-beta decays is addressed by following the Bayesian statistical approach. For the first time, we present a quantitative description of experimental power to distinguish between normal and inverted neutrino mass orderings. Taking an exposure of ${10}^4\mathrm{kg}\mathrm{yr}$ and a background rate of $10^{-4}\text{counts}/(\mathrm{keV}\mathrm{kg}\mathrm{yr})$, we find that a moderate evidence for normal neutrino mass ordering (i.e., with a Bayes factor $\mathcal{B}$ given by $\ln (\mathcal{B})\simeq 2.5$ or a probability about 92.3% according to the Jeffreys scale) can be achieved if the true value of effective neutrino mass $m_{\beta \beta }$ turns out to be below 0.01 eV.

We systematically study the chiral symmetry breaking and restoration in the presence of a pure electric field in the Nambu–Jona-Lasinio model at finite temperature and baryon chemical potential. In addition, we also study the effect of the chiral phase transition on the charged pair production due to the Schwinger mechanism. For these purposes, a general formalism for parallel electric and magnetic fields is developed at finite temperature and chemical potential for the first time. In the pure electric field limit $B\to 0$, we compute the order parameter, the transverse-to-longitudinal ratio of the Goldstone mode velocities, and the Schwinger pair production rate as functions of the electric field. The inverse catalysis effect of the electric field to chiral symmetry breaking is recovered. And the Goldstone mode is found to disperse anisotropically such that the transverse velocity is always smaller than the longitudinal one, especially at nonzero temperature and baryon chemical potential. As expected, the quark-pair production rate is greatly enhanced by the chiral symmetry restoration.

Rare decay modes of the newly discovered standard-model-like Higgs boson $h$ may test the flavor-changing couplings in the leptoquark sector through the process $h\to {\tau }^{\mp }{\mu }^{\pm }$. Motivated by the recently reported excess in LHC data from the CMS detector, we found that a predicted branching fraction Br($h\to {\tau }^{\mp }{\mu }^{\pm }$) at the level of 1% is possible even though the coupling parameters are subjected to the stringent constraint from the null observation of $\tau \to \mu \gamma$, where the destructive cancellation among amplitudes is achievable by fine-tuning.

The quark propagator is studied under a truncation scheme beyond the rainbow approximation by dressing the quark-gluon vertex nonperturbatively. It is found that, in the chiral limit with dynamical symmetry breaking, the dynamical quark mass and the quark condensate are significantly enhanced due to the non-Abelian contribution arising from the three-gluon interaction compared to those under the rainbow approximation, and the critical strength of the dynamical chiral symmetry breaking is much lowered. The Abelian contribution is much smaller than the non-Abelian contribution. A technical issue on removing the ultraviolet divergences, including the overlapping divergences, is discussed.

Despite their importance for precision QCD calculations, correlations between in- and out-of-jet regions of phase space have never directly been observed. These so-called nonglobal effects are present generically whenever a collider physics measurement is not explicitly dependent on radiation throughout the entire phase space. In this paper, we introduce a novel procedure based on mutual information, which allows us to isolate these nonglobal correlations between measurements made in different regions of phase space. We study this procedure both analytically and in Monte Carlo simulations in the context of observables measured on hadronic final states produced in $e^{+}{e}^{-}$ collisions, though it is more widely applicable. The procedure exploits the sensitivity of soft radiation at large angles to nonglobal correlations, and we calculate these correlations through next-to-leading logarithmic accuracy. The bulk of these nonglobal correlations are found to be described in Monte Carlo simulation. They increase by the inclusion of nonperturbative effects, which we show can be incorporated in our calculation through the use of a model shape function. This procedure illuminates the source of nonglobal correlations and has connections more broadly to fundamental quantities in quantum field theory.

We study the transverse-momentum-dependent (TMD) evolution of the Collins azimuthal asymmetries in $e^{+}{e}^{-}$ annihilations and semi-inclusive hadron production in deep inelastic scattering processes. All the relevant coefficients are calculated up to the next-to-leading-logarithmic-order accuracy. By applying the TMD evolution at the approximate next-to-leading-logarithmic order in the Collins-Soper-Sterman formalism, we extract transversity distributions for $u$ and $d$ quarks and Collins fragmentation functions from current experimental data by a global analysis of the Collins asymmetries in back-to-back dihadron productions in $e^{+}{e}^{-}$ annihilations measured by BELLE and BABAR collaborations and semi-inclusive hadron production in deep inelastic scattering data from HERMES, COMPASS, and JLab HALL A experiments. The impact of the evolution effects and the relevant theoretical uncertainties are discussed. We further discuss the TMD interpretation for our results and illustrate the unpolarized quark distribution, transversity distribution, unpolarized quark fragmentation, and Collins fragmentation functions depending on the transverse momentum and the hard momentum scale. We make detailed predictions for future experiments and discuss their impact.

We construct and analyze nonsupersymmetric SO(10) standard model extensions which explain dark matter (DM) through the fermionic Higgs portal. In these SO(10)-based models the DM particle is naturally stable since a $Z_2$ discrete symmetry, the matter parity, is left at the end of the symmetry breaking chain to the standard model. Potentially realistic models contain the $\mathbf{10}$ and $\mathbf{45}$ fermionic representations from which a neutralino-like mass matrix with arbitrary mixings can be obtained. Two different SO(10) breaking chains will be analyzed in light of gauge coupling unification: the standard path $\mathrm{SU}(5)\times U(1{)}_X$ and the left-right symmetry intermediate chain. The former opens the possibility of a split supersymmetric-like spectrum with an additional (inert) scalar doublet, while the later requires additional exotic scalar representations associated to the breaking of the left-right symmetry.

We interpret the 2 TeV excesses at the LHC in a left-right symmetric model with Higgs doublets and spontaneous $D$-parity violation. The light neutrino masses are understood via a linear seesaw, suppressed by a high $D$-parity breaking scale, and the heavy neutrinos have a pseudo-Dirac character. In addition, with a suppressed right-handed gauge coupling $g_R/g_L\approx 0.6$ in an $SO(10)$ embedding, we can thereby interpret the observed $eejj$ excess at CMS. We show that it can be reconciled with the diboson and dijet excesses within a simplified scenario based on our model. Moreover, we find that the mixing between the light and heavy neutrinos can be potentially large, which would induce dominant nonstandard contributions to neutrinoless double beta decay via long-range $\lambda$ and $\eta$ neutrino exchange.

A measurement of the correlations between the polar angles of leptons from the decay of pair-produced $t$ and $\overline{t}$ quarks in the helicity basis is reported, using proton-proton collision data collected by the ATLAS detector at the LHC. The dataset corresponds to an integrated luminosity of $4.6{\mathrm{fb}}^{-1}$ at a center-of-mass energy of $\sqrt{s}=7\mathrm{TeV}$ collected during 2011. Candidate events are selected in the dilepton topology with large missing transverse momentum and at least two jets. The angles ${\theta }_1$ and ${\theta }_2$ between the charged leptons and the direction of motion of the parent quarks in the $t\overline{t}$ rest frame are sensitive to the spin information, and the distribution of $\cos {\theta }_1·\cos {\theta }_2$ is sensitive to the spin correlation between the $t$ and $\overline{t}$ quarks. The distribution is unfolded to parton level and compared to the next-to-leading order prediction. A good agreement is observed.