Vector (${\rm Y}$) and pseudoscalar (${\eta }_b$) bottonium ground states are studied at finite temperature in the framework of thermal Hilbert moment QCD sum rules. The mass, the onset of perturbative QCD in the complex squared energy plane, $s_0$, the leptonic decay constant, and the total width are determined as a function of the temperature. Results in both channels show very little temperature dependence of the mass and of $s_0$, in line with expectations. However, the width and the leptonic decay constant exhibit a very strong $T$ dependence. The former increases with increasing temperature, as in the case of light- and heavy-light-quark systems, but close to the critical temperature $T_c$ and for $T/T_c\simeq 0.9$ it drops dramatically, approaching its value at $T=0$, as obtained recently in this framework for charmonium states. The leptonic decay constant is basically a monotonically increasing function of the temperature, also as obtained in the charmonium channel. These results are interpreted as the survival of these bottonium states above $T_c$, in line with lattice QCD results.

We explore the viscosities of a photon gas by means of the Euler-Heisenberg effective theory and quantum electrodynamics at zero electron chemical potential. We find parametric estimates that show a very large shear viscosity and an extremely small bulk viscosity (reflecting the very weak coupling simultaneously with a very approximate dilatation invariance). The system is of some interest because it exemplifies very neatly the influence of the breaking of scale invariance on the bulk viscosity.

Stability about cosmological background solutions to the bimetric Hassan-Rosen theory is studied. The results of this analysis are presented, and it is shown that a large class of cosmological backgrounds is classically unstable. This sets serious doubts on the physical viability of the Hassan-Rosen theory—and in turn also of the de Rham-Gadabaze-Tolley model. A way to overcome this instability by means of curvature-type deformations is discussed.

Classical scalar fields have been considered as a possible effective description of dark matter. We show that, for any metric theory of gravity, no static, spherically symmetric, regular, spatially localized, attractive, stable spacetime configuration can be sourced by the coherent excitation of a scalar field with positive definite energy density and no Noether charges. In the weak field regime, the result also applies for configurations with a repulsive gravitational potential. This extends Derrick’s theorem to the case of a general (noncanonical) scalar field, including the self-gravitational effects. Some possible ways out are briefly discussed.

This work comprises a study upon the quantization and the renormalizability of the generalized electrodynamics of spinless charged particles (mesons), namely, the generalized scalar electrodynamics ($GSQE{D}_4$). The theory is quantized in the covariant framework of the Batalin-Fradkin-Vilkovisky method. Thereafter, the complete Green’s functions are obtained through functional methods and a proper discussion on the theory’s renormalizability is also given. Next, we present the computation and further discussion on the radiative correction at $\alpha$ order; and, as it turns out, an unexpected $m_P$-dependent divergence on the mesonic sector of the theory is found. Furthermore, in order to show the effectiveness of the renormalization procedure on the present theory, we also give a diagrammatic discussion on the photon self-energy at ${\alpha }^2$ order, where we observe contributions from the meson self-energy function. Afterwards, we present the expressions of the counterterms and effective coupling of the theory, obtaining from the latter an energy range where the theory is defined by $m^2\le k^2<m_P^2$. We also shown in our final discussion that the new divergence is absorbed suitably by the mass counterterm ${\delta }_{Z_0}$, showing therefore that the gauge Ward-Fradkin-Takahashi identities are satisfied still.

If quantum mechanics governs nature, black holes must evolve unitarily, providing a powerful constraint on the dynamics of quantum gravity. Such evolution apparently must in particular be nonlocal, when described from the usual semiclassical geometric picture, in order to transfer quantum information into the outgoing state. While such transfer from a disintegrating black hole has the dangerous potential to be violent to generic infalling observers, this paper proposes the existence of a more innocuous form of information transfer, to relatively soft modes in the black hole atmosphere. Simplified models for such nonlocal transfer are described and parameterized, within a possibly more basic framework of networked Hilbert spaces. Sufficiently sensitive measurements by infalling observers may detect departures from Hawking’s predictions, and in generic models black holes decay more rapidly. Constraints of consistency—internally and with known and expected features of physics—restrict the form of information transfer, and should provide important guides to discovery of the principles and mechanisms of the more fundamental nonlocal mechanics.

The nature of the supermassive black hole candidates in galactic nuclei can be tested by analyzing the profile of the $\mathrm{K}\alpha$ iron line observed in their x-ray spectrum. In this paper, we consider the possibility that the spacetime in the immediate vicinity of these objects may be described by some nonvacuum exact solutions of Einstein’s equations resulting as the end state of gravitational collapse. The vacuum far away portion of the spacetime is described by the Schwarzschild metric, while the interior part may be either regular or have a naked singularity at the center. The iron line generated around this class of objects has specific features, which can be used to distinguish such objects from Kerr black holes. In particular, their iron line cannot have the characteristic low-energy tail of the line generated from accretion disks around fast-rotating Kerr black holes. We can thus conclude that the supermassive black hole candidates whose spin parameter has been estimated to be close to 1 assuming the Kerr background cannot be this kind of objects.

We present a solution for the Einstein-Maxwell equations which unifies both the magnetic Bertotti-Robinson and Melvin solutions as a single metric in the axially symmetric coordinates $\{t,\rho ,z,\phi \}$. Depending on the strength of magnetic field the spacetime manifold, unlike the cases of separate Bertotti-Robinson and Melvin spacetime, develops singularity on the symmetry axis ($\rho =0$). Our analysis shows, beside other things, that there are regions inaccessible to all null geodesics.

Spherical systems with polytropic equations of state are of great interest in astrophysics. They are widely used to describe neutron stars, red giants, white dwarfs, brown dwarfs, main sequence stars, galactic halos, and globular clusters of diverse sizes. In this paper we construct analytically a family of self-gravitating spherical models in the post-Newtonian approximation of general relativity. These models present interesting cusps in their density profiles which are appropriate for the modeling of galaxies and dark matter halos. The systems described here are anisotropic in the sense that their equiprobability surfaces in velocity space are nonspherical, leading to an overabundance of radial or circular orbits, depending on the parameters of the model under consideration. Among the family of models, we find the post-Newtonian generalization of the Plummer and Hernquist models. A close inspection of their equation of state reveals that these solutions interpolate smoothly between a polytropic sphere in the asymptotic region and an inner core that resembles an isothermal sphere. Finally, we study the thermodynamics of these models and argue for their stability.

We present here bounds on neutrino masses from the combination of recent Planck cosmic microwave background (CMB) measurements and galaxy clustering information from the Baryon Oscillation Spectroscopic Survey, part of the Sloan Digital Sky Survey-III. We use the full shape of either the photometric angular clustering (Data Release 8) or the 3D spectroscopic clustering (Data Release 9) power spectrum in different cosmological scenarios. In the $\Lambda \mathrm{CDM}$ scenario, spectroscopic galaxy clustering measurements improve significantly the existing neutrino mass bounds from Planck data. We find $\sum _{}^{}{m}_{\nu }<0.39\mathrm{eV}$ at 95% confidence level for the combination of the 3D power spectrum with Planck CMB data (wi lensing included) and Wilkinson Microwave Anisoptropy Probe 9-year polarization measurements. Therefore, robust neutrino mass constraints can be obtained without the addition of the prior on the Hubble constant from Hubble Space Telescope. In extended cosmological scenarios with a dark energy fluid or with nonflat geometries, galaxy clustering measurements are essential to pin down the neutrino mass bounds, providing in the majority of cases better results than those obtained from the associated measurement of the baryon acoustic oscillation scale only. In the presence of a freely varying (constant) dark energy equation of state, we find $\sum _{}^{}{m}_{\nu }<0.49\mathrm{eV}$ at 95% confidence level for the combination of the 3D power spectrum with Planck CMB data (with lensing included) and Wilkinson Microwave Anisoptropy Probe 9-year polarization measurements. This same data combination in nonflat geometries provides the neutrino mass bound $\sum _{}^{}{m}_{\nu }<0.35\mathrm{eV}$ at 95% confidence level.

The existence of an exotic long-lived negatively charged massive particle, i.e., $X^{-}$, during big bang nucleosynthesis can affect primordial light element abundances. In particular, the final abundance of ${}^7\mathrm{Li}$, mainly originating from the electron capture of ${}^7\mathrm{Be}$, has been suggested to be made smaller by the ${}^7\mathrm{Be}$ destruction via the radiative $X^{-}$ capture of ${}^7\mathrm{Be}$ followed by the radiative proton capture of the bound state of ${}^7\mathrm{Be}$ and $X^{-}$ (${}^7\mathrm{Be}_X$). We suggest a new route of ${}^7\mathrm{Be}_X$ formation, that is the ${}^7\mathrm{Be}$ charge exchange at the reaction of ${}^7\mathrm{Be}^{3+}$ ion and $X^{-}$. The formation rate depends on the number fraction of the ${}^7\mathrm{Be}^{3+}$ ion, the charge exchange cross section of ${}^7\mathrm{Be}^{3+}$, and the probability that produced excited states ${}^7\mathrm{Be}_X^{*}$ are converted to the ground state. We estimate respective quantities affecting the ${}^7\mathrm{Be}_X$ formation rate and find that this reaction pathway can be more important than the ordinary radiative recombination of ${}^7\mathrm{Be}$ and $X^{-}$. The effect of the charge exchange reaction is then shown in a latest nuclear reaction network calculation. Quantum physical model calculations for related reactions are needed to precisely estimate the efficiency of this pathway in the future.

The newly developed approach to model nucleon generalized parton distributions (GPDs) $H$ and $E$ is based on two types of their representation in terms of double distributions. Within this approach, we reconsider the derivation of GPD sum rules that allow one to use border functions $H(x,x)$ and $E(x,x)$ instead of full GPDs $H(x,\xi )$ and $E(x,\xi )$ in the integrals producing Compton form factors of deeply virtual Compton scattering. Using factorized double distribution Ansatz to model GPDs, we discuss the relation between the border functions and underlying parton densities. We find that a substantial contribution to the $H(x,x)$ border function comes from the extra term required by new double distribution representations and related to $E(x,\xi )$ GPD.

The dispersive approach to QCD is applied to the study of the inclusive $\tau$ lepton hadronic decay. This approach provides the unified integral representations for the hadronic vacuum polarization function, related $R$ function, and Adler function. These representations account for the intrinsically nonperturbative constraints, which originate in the kinematic restrictions on the functions on hand, and retain the effects due to hadronization, which play a valuable role in the analysis of the strong interaction processes at low energies. The dispersive approach proves to be capable of describing recently updated ALEPH and OPAL experimental data on inclusive $\tau$ lepton hadronic decay in vector and axial-vector channels. The vicinity of values of the QCD scale parameter obtained in both channels testifies to the potential ability of the developed approach to describe the aforementioned data in a self-consistent way.

Now that one has been found, the search for signs of more scalars is a primary task of current and future experiments. In the motivated hypothesis that the extra Higgs bosons of the next-to-minimal supersymmetric Standard Model are the lightest new particles around, we outline a possible overall strategy to search for signs of the $CP$-even states. This work complements Barbieri et al. [Phys. Rev. D 87, 115018 (2013)].

In the two Higgs doublet models, $\tan \beta$ is an important parameter, which is defined as the ratio of the vacuum expectation values of the doublets. We study how accurately $\tan \beta$ can be determined at linear colliders via the precision measurement of the decay branching fraction of the standard model (SM)–like Higgs boson. Since the effective coupling constants of the Higgs boson with the weak gauge bosons are expected to be measured accurately, the branching ratios can be precisely determined. Consequently, $\tan \beta$ can be determined with a certain amount of accuracy. Comparing the method to those using direct production of the additional Higgs bosons, we find that, depending on the type of Yukawa interactions, the precision measurement of the decay of the SM-like Higgs boson can be the best way to determine $\tan \beta$, when the deviations in the coupling constants with the gauge boson from the SM prediction are observed at linear colliders.

A Reply to the Comment by C. M. Ho and T. J. Weiler.

The spacetime of Ho and Weiler [Phys. Rev. D 87, 045004 (2013)] supposedly admitting closed timelike curves (CTCs) is flat Minkowski spacetime with a compactified coordinate and can only contain CTCs if the compact direction is chosen to be timelike. This case of a “periodic time” is probably the simplest example of a causality-violating spacetime; it trivially satisfies all energy conditions usually assumed in general relativity, and its geodesics are just straight lines. Its relevance for phenomenology of the LHC, on the other hand, depends on consistency with observational constraints on gravity, as is mentioned in general but not discussed in any detail by Ho and Weiler. We verify a basic consistency check for stationary sources.

We determine the all-loop dressing phases of the ${\mathrm{AdS}}_3/{\mathrm{CFT}}_2$ integrable system related to type IIB string theory on ${\mathrm{AdS}}_3\times {\mathrm{S}}^3\times {\mathrm{T}}^4$ by solving the recently found crossing relations and studying their singularity structure. The two resulting phases present a novel structure with respect to the ones appearing in ${\mathrm{AdS}}_5/{\mathrm{CFT}}_4$ and ${\mathrm{AdS}}_4/{\mathrm{CFT}}_3$. In the strongly coupled regime, their leading order reduces to the universal Arutyunov–Frolov–Staudacher phase as expected. We also compute their subleading order and compare it with recent one-loop perturbative results and comment on their weak-coupling expansion.