We find the spectrum and wave functions of the heavy-light mesons in ($1+1$)-dimensional QCD in the ’t Hooft limit, both in the rest frame, using the Coulomb (axial) gauge, and on the light cone. Our emphasis is on the effects of chiral symmetry breaking on the spectrum. While dynamical equations in both cases look different, the results for the spectrum are identical. The chiral symmetry breaking is clearly seen from the gap and Bethe-Salpeter equations in the laboratory frame. At the same time, while vacuum is trivial on the light cone (no chiral condensate), the effects of the spontaneous breaking of the chiral symmetry manifest themselves in the same way, as it follows from the coincidence of the spectra obtained from the laboratory-frame Bethe-Salpeter equation on the one hand, and the light-cone ’t Hooft-type equation on the other.

The impact a new neutral light particle of spin 0, $1/2$, 1, or $3/2$ could have on the tiny width of a light Higgs boson is systematically analyzed. To this end, we include all the relevant effective interactions, whether renormalizable or not, and review the possible signatures in the Higgs decay modes with missing energy. This includes the fully invisible Higgs boson decay, as well as modes with standard model gauge bosons or fermions in the final state. In many cases, simply preventing these modes from being dominant suffices to set tight model-independent constraints on the masses and couplings of the new light states.

The first measurements of the coherence factor $R_{K_S^{0}K\pi }$ and the average strong-phase difference ${\delta }_D^{K_S^{0}K\pi }$ in $D^0\to K_S^0{K}^{\mp }{\pi }^{\pm }$ decays are reported. These parameters can be used to improve the determination of the unitary triangle angle $\gamma$ in $B^{-}\to \tilde{D}{K}^{-}$ decays, where $\tilde{D}$ is either a $D^0$ or a ${\overline{D}}^0$ meson decaying to the same final state, and also in studies of charm mixing. The measurements of the coherence factor and strong-phase difference are made using quantum-correlated, fully reconstructed $D^0{\overline{D}}^0$ pairs produced in $e^{+}{e}^{-}$ collisions at the $\psi (3770)$ resonance. The measured values are $R_{K_S^{0}K\pi }=0.73\pm 0.08$ and ${\delta }_D^{K_S^{0}K\pi }=(8.3\pm 15.2)°$ for an unrestricted kinematic region and $R_{K^{*}K}=1.00\pm 0.16$ and ${\delta }_D^{K^{*}K}=(26.5\pm 15.8)°$ for a region where the combined $K_S^0{\pi }^{\pm }$ invariant mass is within $100\mathrm{MeV}/c^2$ of the $K^{*}(892{)}^{\pm }$ mass. These results indicate a significant level of coherence in the decay. In addition, isobar models are presented for the two decays, which show the dominance of the $K^{*}(892{)}^{\pm }$ resonance. The branching ratio $\mathcal{B}(D^0\to K_S^0{K}^{+}{\pi }^{-})/\mathcal{B}(D^0\to K_S^0{K}^{-}{\pi }^{+})$ is determined to be $0.592\pm 0.044(\mathrm{stat})\pm 0.018(\mathrm{syst})$, which is more precise than previous measurements.

In Phys. Rev. D 84, 107301 (2011), we presented our results on using a general relativistic two-fluid formalism to study the hydrostatic equilibrium configuration of an admixture of degenerate dark matter and normal nuclear matter. In this work, we present more analysis to complement our previous findings. We study the radial oscillation modes of these compact stars in detail. We find that these stars in general have two classes of oscillation modes. For a given total mass of the star, the first class of modes is insensitive to the dark-matter particle mass. They also reduce properly to the oscillation modes of the corresponding ordinary neutron star, with the same total mass, when the mass fraction of dark matter tends to zero. On the other hand, the second class of modes is due mainly to the dark-matter fluid. In the small dark-matter mass fraction limit, these modes are characterized purely by the oscillations of dark matter, while the normal matter is essentially at rest. In the intermediate regime where the mass fractions of the two fluids are comparable, the normal matter oscillates with the dark matter due to their coupling through gravity. In contrast to the first class of modes, the frequencies of these dark-matter dominated modes depend sensitively on the mass of dark-matter particles.

We estimate the vector interaction strength of the Polyakov–Nambu–Jona-Lasinio (PNJL) parametrizations, assuming that its transition curves should be as close as possible to the recently studied RMF-PNJL hadron-quark phase diagrams. Such diagrams are obtained matching relativistic mean-field hadronic models and the PNJL quark ones. By using this method we found for the magnitude of the vector interaction, often treated as a free parameter, a range of $7.66{\mathrm{GeV}}^{-2}\lesssim G_V\lesssim 16.13{\mathrm{GeV}}^{-2}$, or equivalently, $1.52\lesssim G_V/G_s\lesssim 3.2$, with $G_s$ being the scalar coupling constant of the model. These values are compatible but restrict the range of $4{\mathrm{GeV}}^{-2}\lesssim G_V\lesssim 19{\mathrm{GeV}}^{-2}$, recently obtained from lattice QCD data through a different mean-field model approach.

The behavior of fermions in the presence of Lorentz and $CPT$ violation is studied. Allowing for operators of any mass dimension, we classify all Lorentz-violating terms in the quadratic Lagrange density for free fermions. The result is adapted to obtain the effective Hamiltonian describing the propagation and mixing of three flavors of left-handed neutrinos in the presence of Lorentz violation involving operators of arbitrary mass dimension. A characterization of the neutrino coefficients for Lorentz violation is provided via a decomposition using spin-weighted spherical harmonics. The restriction of the general theory to various special cases is discussed, including among others the renormalizable limit, the massless scenario, flavor-blind and oscillation-free models, the diagonalizable case, and several isotropic limits. The formalism is combined with existing data on neutrino oscillations and kinematics to extract a variety of measures of coefficients for Lorentz and $CPT$ violation. For oscillations, we use results from the short-baseline experiments LSND and MiniBooNE to obtain explicit sensitivities to effects from flavor-mixing Lorentz-violating operators up to mass dimension 10, and we present methods to analyze data from long-baseline experiments. For propagation, we use time-of-flight measurements from the supernova SN1987A and from a variety of experiments including MINOS and OPERA to constrain oscillation-free Lorentz-violating operators up to mass dimension 10, and we discuss constraints from threshold effects in meson decays and Čerenkov emission.

We present a first calculation of transverse momentum-dependent nucleon observables in dynamical lattice QCD employing nonlocal operators with staple-shaped, “process-dependent” Wilson lines. The use of staple-shaped Wilson lines allows us to link lattice simulations to TMD effects determined from experiment, and, in particular, to access nonuniversal, naively time-reversal odd TMD observables. We present and discuss results for the generalized Sivers and Boer-Mulders transverse momentum shifts for the SIDIS and DY cases. The effect of staple-shaped Wilson lines on T-even observables is studied for the generalized tensor charge and a generalized transverse shift related to the worm-gear function $g_{1T}$. We emphasize the dependence of these observables on the staple extent and the Collins-Soper evolution parameter. Our numerical calculations use an $n_f=2+1$ mixed action scheme with domain wall valence fermions on an Asqtad sea and pion masses 369 MeV as well as 518 MeV.

We calculate cross sections for $gg\to Q\overline{Q}Q\overline{Q}$ in the high-energy approximation in the mixed (longitudinal momentum fraction, impact parameter) and momentum space representations. Besides the total cross section as a function of subsystem energy also differential distributions (in quark rapidity, transverse momentum, $QQ$, $Q\overline{Q}$ invariant mass) are presented. The elementary cross section is used to calculate production of $(c\overline{c})(c\overline{c})$ in single-parton scattering (SPS) in proton-proton collisions. We present integrated cross section as a function of proton-proton center-of-mass energy as well as differential distribution in $M_{(c\overline{c})(c\overline{c})}$. The results are compared with corresponding results for double-parton scattering (DPS) discussed recently in the literature. We find that the considered SPS contribution to $(c\overline{c})(c\overline{c})$ production is at high energy ($\sqrt{s}>5\mathrm{TeV}$) much smaller than that for DPS contribution.

We analyze open string vertex operators describing connection gauge fields for spin 3 in Vasiliev’s framelike formalism and perform their extended Becchi-Rouet-Stora-Tyutin analysis. Gauge symmetry transformations, generalized zero torsion constraints relating extra fields to the dynamical framelike field, and the relation between the dynamical framelike field and fully symmetric Fronsdal’s field for spin 3 are all realized in terms of Becchi-Rouet-Stora-Tyutin constraints on these vertex operators in string theory. Using the construction, we analyze the 3-point correlator for the spin 3 field and calculate Chern-Simons type cubic interactions described by the 3-derivative Berends-Burgers-Van Dam type vertex in the framelike formalism.

We study compactifications of Matrix theory on twisted tori and noncommutative versions of them. As a first step, we review the construction of multidimensional twisted tori realized as nilmanifolds based on certain nilpotent Lie algebras. Subsequently, matrix compactifications on tori are revisited, and the previously known results are supplemented with a background of a noncommutative torus with nonconstant noncommutativity and an underlying nonassociative structure on its phase space. Next, we turn our attention to three- and six-dimensional twisted tori, and we describe consistent backgrounds of Matrix theory on them by stating and solving the conditions which describe the corresponding compactification. Both commutative and noncommutative solutions are found in all cases. Finally, we comment on the correspondence among the obtained solutions and flux compactifications of 11-dimensional supergravity, as well as on relations among themselves, such as Seiberg-Witten maps and $T$-duality.

Using a string inspired model we construct gravity duals generalizing $p_x$ and $p_x+i{p}_y$ superconductors. Introducing a Chern-Simons coupling in the gravity side we demonstrate the ability to control which phase dominates at low temperatures and focus on the chiral $p_x+i{p}_y$ phase. We study the fermionic spectral function and establish that the behavior is rather different from the standard $p$-wave two-nodes model.

We investigate the nonperturbative stability of asymptotically anti-de Sitter gravity coupled to tachyonic scalar fields with mass saturating the Breitenlohner-Freedman bound. Such “designer gravity” theories admit a large class of boundary conditions at asymptotic infinity. At this mass, the asymptotic behavior of the scalar field develops a logarithmic branch, and previous attempts at proving a minimum energy theorem failed due to a large radius divergence in the spinor charge. In this paper, we finally resolve this issue and derive a lower bound on the conserved energy. Just as for masses slightly above the Breitenlohner-Freedman bound, a given scalar potential can admit two possible branches of the corresponding superpotential, one analytic and one nonanalytic. The key point again is that existence of the nonanalytic branch is necessary for the energy bound to hold. We discuss several AdS/CFT applications of this result, including the use of double-trace deformations to induce spontaneous symmetry breaking.

We investigate anomalies on heterotic orbifolds and their blowups. We give a simple example of an orbifold blowup which contains anomalous $U(1)$ symmetries that are canceled by axions which couple non-universally to the different gauge groups, thus clarifying some confusion which recently arose in the literature concerning anomaly universality. We argue that non-universal axionic couplings are the general case, and that the couplings are only universal in the case of orbifolds. We comment on the consequences of this non-universality for discrete $R$ symmetries. We furthermore investigate the origin of discrete ($R$ and non-$R$) symmetries on smooth Calabi–Yau manifolds.

Connections between universes through tunneling space-times could make the multiverse a physical entity able to be observed from our own single universe. In this paper we first study the thermal properties of the static Klein-bottle holes and then consider one of the potentially observable effects from wormholes, ringholes, and nonorientable tunnelings when they are converted into time machines connecting other universes with ours own, that is a randomly varying in space and time thermal radiation which, with an unpredictable cadence, randomly manifested to a far observer as a short, occasional pulse with very high intensity and fluence which would be made of black body phantom or ordinary radiation. We discuss the odds for these bursts of thermal radiation to be eventually observable.

The loss rate of linear momentum from a binary system composed of compact objects (radially falling towards each other under mutual gravitational influence) has been investigated using the multipolar post-Minkowskian approach. The 2.5PN accurate analytical formula for the linear momentum flux is provided, in terms of the separation of the two objects, in harmonic coordinates, both for a finite and an infinite initial separation. The 2.5PN formulas for the linear momentum flux are finally used to estimate the recoil velocity accumulated during a premerger phase of the binary evolution.

The advanced versions of the LIGO and Virgo ground-based gravitational-wave detectors are expected to operate from three sites: Hanford, Livingston, and Cascina. Recent proposals have been made to place a fourth site in Australia or India, and there is the possibility of using the Large Cryogenic Gravitational Wave Telescope in Japan to further extend the network. Using Bayesian parameter-estimation analyses of simulated gravitational-wave signals from a range of coalescing-binary locations and orientations at fixed distance or signal-to-noise ratio, we study the improvement in parameter estimation for the proposed networks. We find that a fourth detector site can break degeneracies in several parameters; in particular, the localization of the source on the sky is improved by a factor of $\sim 3–4$ for an Australian site, or $\sim 2.5–3.5$ for an Indian site, with more modest improvements in distance and binary inclination estimates. This enhanced ability to localize sources on the sky will be crucial in any search for electromagnetic counterparts to detected gravitational-wave signals.

A leading approach to the modeling of extreme mass ratio inspirals involves the treatment of the smaller mass as a point particle and the computation of a regularized self-force acting on that particle. In turn, this computation requires knowledge of the regularized retarded field generated by the particle. A direct calculation of this regularized field may be achieved by replacing the point particle with an effective source and solving directly a wave equation for the regularized field. This has the advantage that all quantities are finite and require no further regularization. In this work, we present a method for computing an effective source which is finite and continuous everywhere, and which is valid for a scalar point particle in arbitrary geodesic motion in an arbitrary background spacetime. We explain in detail various technical and practical considerations that underlie its use in several numerical self-force calculations. We consider as examples the cases of a particle in a circular orbit about Schwarzschild and Kerr black holes, and also the case of a particle following a generic timelike geodesic about a highly spinning Kerr black hole. We provide numerical $C$ code for computing an effective source for various orbital configurations about Schwarzschild and Kerr black holes.

Based on a canonical framework, we investigate the critical behavior of Born-Infeld AdS black holes in higher dimensions. As a special case, considering the appropriate limit, we also analyze the critical phenomena for Reissner-Nordstrom AdS black holes. The critical points are marked by the divergences in the heat capacity at constant charge. The static critical exponents associated with various thermodynamic entities are computed and shown to satisfy the thermodynamic scaling laws. These scaling laws have also been found to be compatible with the static scaling hypothesis. Furthermore, we show that the values of these exponents are universal and do not depend on the spatial dimensionality of the AdS space. We also provide a suggestive way to calculate the critical exponents associated with the spatial correlation which satisfy the scaling laws of the second kind.

Only a severely restricted class of tensor fields can provide classical spacetime geometries, namely those that can carry matter field equations which are predictive, interpretable, and quantizable. These three conditions on matter translate into three corresponding algebraic conditions on the underlying tensorial geometry: the latter must be hyperbolic, time-orientable, and energy-distinguishing. Lorentzian metrics, on which general relativity and the standard model of particle physics are built, present just the simplest tensorial spacetime geometry satisfying these conditions. The problem of finding gravitational dynamics—for the general tensorial spacetime geometries satisfying the above minimum requirements—is reformulated in this paper as a system of linear partial differential equations, in the sense that their solutions yield the actions governing the corresponding spacetime geometry. Thus, the search for modified gravitational dynamics is reduced to a clear mathematical task.

We compute the canonical partition function for quantum black holes in the approach of loop quantum gravity (LQG). We argue that any quantum theory of gravity in which the horizon area is built of noninteracting constituents cannot yield qualitative corrections to the Bekenstein-Hawking (B-H) area law, but corrections to the area law can arise as a consequence of additional constraints inducing interactions between the constituents. In LQG this is implemented by requiring spherical horizons. The canonical approach for LQG seemingly favors a logarithmic correction to the B-H law with a coefficient of $-\frac{1}{2}$. Our initial calculation of the partition function uses certain approximations that, we show, do not qualitatively affect the expression for the black hole entropy. We later discuss the quantitative corrections to these results when the simplifying approximations are relaxed and the full LQG spectrum is dealt with. We show how these corrections can be recovered to all orders in perturbation theory. However, the convergence properties of the perturbative series remain unknown for now.