Einstein-aether theory is general relativity coupled to a dynamical, unit timelike vector. If this vector is restricted in the action to be hypersurface orthogonal, the theory is identical to the IR limit of the extension of Hořava gravity proposed by Blas, Pujolàs and Sibiryakov. Hypersurface orthogonal solutions of Einstein-aether theory are solutions to the IR limit of this theory, hence numerous results already obtained for Einstein-aether theory carry over.

The concept of incomplete vector-meson dominance and Regge models is applied to the transition form factor of the pion. First, we argue that variants of the chiral quark model fulfilling the chiral anomaly may violate the Terazawa-West unitarity bounds, as these bounds are based on unverified assumptions for the real parts of the amplitudes, precluding a possible presence of polynomial terms. A direct consequence is that the transition form factor need not necessarily vanish at large values of the photon virtuality. Moreover, in the range of the BABAR experiment, the Terazawa-West bound is an order of magnitude above the data, thus is of formal rather than practical interest. Then we demonstrate how the experimental data may be properly explained with incomplete vector-meson dominance in a simple model with one state, as well as in more sophisticated Regge models. Generalizations of the simple Regge model along the lines of Dominguez result in a proper description of the data, where one may adjust the parameters in such a way that the Terazawa-West bound is satisfied or violated. We also impose the experimental constraint from the $Z\to {\pi }_0\gamma$ decay. Finally, we point out that the photon momentum asymmetry parameter may noticeably influence the precision analysis.

We present a next-to-leading-order QCD calculation of the cross section and longitudinal spin asymmetry in single-inclusive charged-lepton production, $pp\to {\ell }^{\pm }X$, at the Relativistic Heavy Ion Collider, where the lepton is produced in the decay of an electroweak gauge boson. Our calculation is presented in terms of a multipurpose Monte Carlo integration program that may be readily used to include experimental spin-asymmetry data in a global analysis of helicity parton densities. We perform a toy global analysis, studying the impact of anticipated Relativistic Heavy Ion Collider data on our knowledge about the polarized antiquark distributions.

It is shown that intrinsic transverse parton momenta $p_T$ in semi-inclusive deep-inelastic scattering (SIDIS) and the Drell-Yan process (DY) are very well and consistently described in the Gauss model with energy-dependent Gaussian widths. Our work solidifies the basis for future studies of $p_T$-effects. We also discuss the Cahn and Boer-Mulders effect in SIDIS and DY.

A search for the $Z(3930)$ resonance in $\gamma \gamma$ production of the $D\overline{D}$ system has been performed using a data sample corresponding to an integrated luminosity of $384{\mathrm{fb}}^{-1}$ recorded by the BABAR experiment at the PEP-II asymmetric-energy electron-positron collider. The $D\overline{D}$ invariant mass distribution shows clear evidence of the $Z(3930)$ state with a significance of $5.8\sigma$. We determine mass and width values of $(3926.7\pm 2.7\pm 1.1)\mathrm{MeV}/c^2$ and $(21.3\pm 6.8\pm 3.6)\mathrm{MeV}$, respectively. A decay angular analysis provides evidence that the $Z(3930)$ is a tensor state with positive parity and $C$ parity ($J^{PC}=2^{++}$); therefore we identify the $Z(3930)$ state as the ${\chi }_{c2}(2P)$ meson. The value of the partial width ${\Gamma }_{\gamma \gamma }\times \mathcal{B}(Z(3930)\to D\overline{D})$ is found to be $(0.24\pm 0.05\pm 0.04)\mathrm{keV}$.

We consider a spherically symmetric black hole in equilibrium with surrounding classical matter that is characterized by a nonlinear dependence of the radial pressure $p_r$ on the density $\rho$. We examine under which requirements such an equilibrium is possible. It is shown that if the radial and transverse pressures are equal (Pascal perfect fluid), the equation of state should be approximately linear near the horizon. The corresponding restriction on $\frac{d{p}_r}{d\rho }$ is a direct generalization of the result, previously found for an exactly linear equation of state. In the anisotropic case there is no restriction on the equation of state but the horizon should be simple (nondegenerate).

We study the possible charmoniumlike states with $J^{\mathrm{PC}}=0^{--}$, $0^{-+}$ using the tetraquark interpolating currents with the QCD sum rules approach. The extracted masses are around 4.5 GeV for the $0^{--}$ charmoniumlike states and 4.6 GeV for the $0^{-+}$ charmoniumlike states, while their bottomoniumlike analogues lie around 10.6 GeV. We also discuss the possible decay, production, and experimental search of the $0^{--}$ charmoniumlike state.

We study the relation between the $\mathcal{N}=2$ gauge theory in the $\Omega$ background and the quantized integral system recently proposed by Nekrasov and Shatashvili. We focus on the simplest case, the pure Yang-Mills theory with the $SU(2)$ gauge group and the corresponding sine-Gordon integral model on the complex plane. We analyze the periodic wave function and the corresponding energy spectrum of the sine-Gordon quantum mechanics, and find this model contains information of the low energy effective theory of the gauge theory.

This paper deals mainly with a discussion of three new manifold correction methods and three existing ones, which can numerically preserve or correct all integrals in the conservative post-Newtonian Hamiltonian formulation of spinning compact binaries. Two of them are listed here. One is a new momentum-position scaling scheme for complete consistency of both the total energy and the magnitude of the total angular momentum, and the other is the Nacozy’s approach with least-squares correction of the four integrals including the total energy and the total angular momentum vector. The post-Newtonian contributions, the spin effects, and the classification of orbits play an important role in the effectiveness of these six manifold corrections. They are all nearly equivalent to correct the integrals at the level of the machine epsilon for the pure Kepler problem. Once the third-order post-Newtonian contributions are added to the pure orbital part, three of these corrections have only minor effects on controlling the errors of these integrals. When the spin effects are also included, the effectiveness of the Nacozy’s approach becomes further weakened, and even gets useless for the chaotic case. In all cases tested, the new momentum-position scaling scheme always shows the optimal performance. It requires a little but not much expensive additional computational cost when the spin effects exist and several time-saving techniques are used. As an interesting case, the efficiency of the correction to chaotic eccentric orbits is generally better than one to quasicircular regular orbits. Besides this, the corrected fast Lyapunov indicators and Lyapunov exponents of chaotic eccentric orbits are large as compared with the uncorrected counterparts. The amplification is a true expression of the original dynamical behavior. With the aid of both the manifold correction added to a certain low-order integration algorithm as a fast and high-precision device and the fast Lyapunov indicators of two nearby trajectories, phase space scans for chaos in the spinning compact binary system are given.

We study the internal structure of a two-dimensional dilatonic evaporating black hole based on the Callan, Giddings, Harvey, and Strominger model. At the semiclassical level, a (weak) spacelike singularity was previously found to develop inside the black hole. We employ here a simplified quantum formulation of spacetime dynamics in the neighborhood of this singularity, using a minisuperspace-like approach. Quantum evolution is found to be regular and well defined at the semiclassical singularity. A well-localized initial wave packet propagating towards the singularity bounces off the latter and retains its well-localized form. Our simplified quantum treatment thus suggests that spacetime may extend semiclassically beyond the singularity, and also signifies the specific extension.

Numerical-relativity simulation is performed for rapidly spinning black holes (BHs) in a higher-dimensional spacetime of special symmetries for the dimensionality $6\le d\le 8$. We find that higher-dimensional BHs, spinning rapidly enough, are dynamically unstable against nonaxisymmetric bar-mode deformation and spontaneously emit gravitational waves, irrespective of $d$ as in the case $d=5$ [M. Shibata and H. Yoshino, Phys. Rev. D 81, 021501(R) (2010).]. The critical values of a nondimensional spin parameter for the onset of the instability are $q≔a/{\mu }^{1/(d-3)}\approx 0.74$ for $d=6$, $\approx 0.73$ for $d=7$, and $\approx 0.77$ for $d=8$ where $\mu$ and $a$ are mass and spin parameters. Black holes with a spin smaller than these critical values ($q_{\mathrm{crit}}$) appear to be dynamically stable for any perturbation. Long-term simulations for the unstable BHs are also performed for $d=6$ and 7. We find that they spin down as a result of gravitational-wave emission and subsequently settle to a stable stationary BH of a spin smaller than $q_{\mathrm{crit}}$. For more rapidly spinning unstable BHs, the time scale, for which the new state is reached, is shorter and fraction of the spin-down is larger. Our findings imply that a highly rapidly spinning BH with $q>q_{\mathrm{crit}}$ cannot be a stationary product in the particle accelerators, even if it would be formed as a consequence of a TeV-gravity hypothesis. Its implications for the phenomenology of a mini BH are discussed.

We analyze analytically and numerically the origin of the singularity in the course of the collapse of a wormhole with the exotic scalar field $\Psi$ with negative energy density, and with this field $\Psi$ together with the ordered magnetic field $H$. We do this under the simplifying assumptions of the spherical symmetry and that in the vicinity of the singularity the solution of the Einstein equations depends only on one coordinate (the homogeneous approximation). In the framework of these assumptions we found the principal difference between the case of the collapse of the ordinary scalar field $\Phi$ with the positive energy density together with an ordered magnetic field $H$ and the collapse of the exotic scalar field $\Psi$ together with the magnetic field $H$. The later case is important for the possible astrophysical manifestation of the wormholes.

Because of their higher concentrations and small internal velocities, Milky Way subhalos can be at least as important as the smooth halo in accounting for the GeV positron excess via dark matter annihilation. After showing how this can be achieved in various scenarios, including in Sommerfeld models, we demonstrate that, in this case, the diffuse inverse-Compton emission resulting from electrons and positrons produced in substructure leads to a nearly-isotropic signal close to the level of the isotropic GeV gamma-ray background seen by Fermi. Moreover, we show that HESS cosmic-ray electron measurements can be used to constrain multi-TeV internal bremsstrahlung gamma rays arising from annihilation to charged leptons.

Using the relativistic Hartree-Fock approximation, we calculate the rates of atomic ionization by absorption of pseudoscalar particles in the mass range from 10 to $\sim 50\mathrm{keV}$. We present numerical results for atoms relevant for the direct dark-matter searches (e.g. Ar, Ge, I and Xe), as well as the analytical formula which fits numerical calculations with few per cent accuracy and may be used for multielectron atoms, molecules and condensed matter systems.

We investigate the properties of cold dense quark matter composed of two colors and two flavors of light quarks. In particular, we perform the first model calculation of the full phase diagram at nonzero baryon and isospin density, thus matching the model-independent predictions of chiral perturbation theory at low density to the conjectured phase structure at high density. We confirm the presence of the Fulde-Ferrell phase in the phase diagram and study its dependence on the tunable parameter in the Lagrangian that simulates the effects of the quantum axial anomaly. As a by-product, we clarify the calculation of the thermodynamic potential in the presence of the Fulde-Ferrell pairing, which was previously based on an ad hoc subtraction of an unphysical cutoff artifact. Furthermore, we argue that close to the diquark (or pion) Bose-Einstein condensation transition, the system behaves as a dilute Bose gas so that our simple fermionic model in the mean-field approximation is not quantitatively adequate. We suggest that including thermal fluctuations of the order parameter for Bose-Einstein condensation is crucial for understanding available lattice data.

We construct a low-energy effective Lagrangian for the two-color QCD including the “vector” bosons (mesons with $J^P=1^{-}$ and diquark baryons with $J^P=1^{+}$) in addition to the pseudo-Nambu-Goldstone bosons with a degenerate mass $M_{\pi }$ (mesons with $J^P=0^{-}$ and baryons with $J^P=0^{+}$) based on the chiral symmetry breaking pattern of $SU(2N_f)\to Sp(2N_f)$ in the framework of the hidden local symmetry. We investigate the dependence of the vector boson masses on the baryon number density ${\mu }_B$. We show that the ${\mu }_B$-dependence signals the phase transition of $U(1{)}_B$ breaking. We find that it gives information about mixing among vector bosons: e.g. the mass difference between “$\rho$” and “$\omega$” mesons is proportional to the mixing strength between the diquark baryon with $J^P=1^{+}$ and the antibaryon. We discuss the comparison with lattice data for two-color QCD at finite density.

The framework of a warped extra dimension with the standard model (SM) fields propagating in it is a very well-motivated extension of the SM since it can address both the Planck-weak and flavor hierarchy problems of the SM. Within this framework, solution to the little hierarchy problem motivates extending the SM electroweak (EW) 5D gauge symmetry in such a way that its breakdown to the SM delivers the SM Higgs boson. We study signals at the large hadron collider (LHC) for the extra EW (called coset) gauge bosons, a fundamental ingredient of this framework. The coset gauge bosons, due to their unique EW gauge quantum numbers [doublets of $SU(2{)}_L$], do not couple at leading order to two SM particles. We find that, using the associated production of the charged coset gauge bosons via their coupling to bottom quark and a (light) Kaluza-Klein excitation of the top quark, the LHC can have a $3\sigma$ reach of $\sim 2(2.6)\mathrm{TeV}$ for the coset gauge boson masses with $\sim 100(1000){\mathrm{fb}}^{-1}$ luminosity. Since current theoretical framework(s) suggest an indirect lower limit on coset gauge boson masses of $\gtrsim 3\mathrm{TeV}$, luminosity or energy upgrade of LHC is likely to be crucial in observing these states.

Upper bounds at the weak scale are obtained for all ${\lambda }_{ij}{\lambda }_{im}$ type product couplings of the scalar leptoquark model which may affect $K^0-{\overline{K}}^0$, $B_d-{\overline{B}}_d$, and $B_s-{\overline{B}}_s$ mixing, as well as leptonic and semileptonic $K$ and $B$ decays. Constraints are obtained for both real and imaginary parts of the couplings. We also discuss the role of leptoquarks in explaining the anomalously large $CP$-violating phase in $B_s-{\overline{B}}_s$ mixing.

We introduce a new collider variable, $M_{CT2}$, named as constransverse mass. It is a mixture of “stransverse mass ($M_{T2}$)” and “contransverse mass ($M_{CT}$)” variables, where the usual endpoint structure of $M_{T2}$ distribution can be amplified in the $M_{CT2}$ basis by a large Jacobian factor which is controlled by a trial missing particle mass. Thus, the $M_{CT2}$ projection of events increases our observability to measure several important endpoints from new particle decays, which are usually expected to be buried by irreducible backgrounds with various systematic uncertainties at the LHC. In this paper we explain the phenomenology of endpoint amplification in $M_{CT2}$ projection, and describe how one may employ this variable to measure several meaningful mass constraints of new particles.

We revisit the determination of the pseudocritical line of QCD with four degenerate quarks at nonzero temperature and baryon density by the method of analytic continuation. We determine the pseudocritical couplings at imaginary chemical potentials by high-statistics Monte Carlo simulations and reveal deviations from the simple quadratic dependence on the chemical potential visible in earlier works on the same subject. Finally, we discuss the implications of our findings for the shape of the pseudocritical line at real chemical potential, comparing different possible extrapolations.