International Journal of Modern Physics A

Gauge-invariant descriptions for a free bosonic scalar field of continuous spin in a $d$-dimensional Minkowski space–time using a metric-like formulation are constructed on the basis of a constrained BRST–BFV approach we propose. The resulting BRST–BFV equations of motion for a scalar field augmented by ghost operators contain different sets of auxiliary fields, depending on the manner of a partial gauge-fixing and a resolution of some of the equations of motion for a BRST-unfolded first-stage reducible gauge theory. To achieve an equivalence of the resulting BRST-unfolded constrained equations of motion with the initial irreducible Poincaré group conditions of a Bargmann–Wigner type, it is demonstrated that one should replace the field in these conditions by a class of gauge-equivalent configurations. Triplet-like, doublet-like constrained descriptions, as well as an unconstrained quartet-like non-Lagrangian and Lagrangian formulations, are derived using both Fronsdal-like and new tensor fields. In particular, the BRST–BV equations of motion and Lagrangian using an appropriate set of Lagrangian multipliers in the minimal sector of the respective field and antifield configurations are constructed in a manifest way.

We present a detailed analysis of a rotating black hole surrounded by “quintessence.” This solution represents a fluid with a constant equation of state, $w$, which can for example describe an effective warm dark matter fluid around a black hole. We clarify the conditions for the existence of such a solution and study its structure by analyzing the existence of horizons as well as the extremal case. We show that the deflection angle produced by the black hole depends on the parameters $(c,w)$ which need to obey the condition $cw<0$ because of the weak energy condition, where $c$ is an additional parameter describing the hair of the black hole. In this context, we found that for $w\simeq 0.1$ (consistent with warm dark matter) and $c<0$, the deviation angle is larger than that in the Kerr space–time for direct and retrograde orbits. We also derive an exact solution in the case of $w=-1/3$.

In this study, considering the Fisher information metric (Fisher metric) given by a specific form, which is the form of weights in statistics, we rewrite the Einstein–Hilbert (EH) action. Then, determining the transformation rules of the Fisher metric, etc under the coarse-graining, we perform the coarse-graining toward that rewritten EH action. We finally show an existence of a trivial fixed-point. Here, the existence of a trivial fixed-point is not trivial for us because we consider the metric given by the Fisher metric, which is not the normal metric and has to satisfy some constraint in the formalism of the Fisher metric. We use the path-integral in our analysis. At this time we have to accept that a fundamental constraint in the formalism of the Fisher metric is broken at the quantum level. However we consider we can accept this with the thought that some constraints and causal relations held at the classical level usually get broken at the quantum level. We finds some problems of the Fisher metric. The space–time we consider in this study is two-dimensional.

We propose a holographic map between Einstein gravity coupled to matter in a de Sitter background and large N quantum mechanics of a system of spins. Holography maps a spin model with a finite-dimensional Hilbert space defined on a version of the stretched horizon into bulk gravitational dynamics. The full Hamiltonian of the spin model contains a nonlocal piece which generates chaotic dynamics, widely conjectured to be a necessary part of quantum gravity, and a local piece which recovers the perturbative spectrum in the bulk.

We consider two families of Drinfeld twists generated from a simple Jordanian twist further twisted with 1-cochains. Using combinatorial identities, they are presented as a series expansion in the dilatation and momentum generators. These twists interpolate between two simple Jordanian twists. For an expansion of a family of twists ${{ℱ}}_{L,u}$, we also show directly that the 2-cocycle condition reduces to previously proven identities.

The dynamic study of the harmonic exponential field has been made using the statefinder diagnostic. By the use of a specific method, we find out the statefinder parameters $r$, $s$ according to the deceleration parameter and the redshift. The numerical analysis of these parameters brings out the transition between the accelerated and decelerated phases of the universe. There is also an attracting effect from the SCDM (Standard Cold Dark Matter) model toward the LCDM model ($\mathrm{\Lambda }$CDM). In view of the results this study allows us to classify the exponential harmonic field among the quintessential models.

In general relativity, finding out the geodesics of a given spacetime manifold is an important task because it determines which classical processes are dynamically forbidden. Conserved quantities play an important role in solving the geodesic equations of a general spacetime manifold. Furthermore, knowing all possible conserved quantities of a system gives information about the hidden symmetries of that system since conserved quantities are deeply connected with the symmetries of the system. These are very important in their own right. Conserved quantities are also useful to capture certain features of spacetime manifold for an asymptotic observer. In this article, we show the existence of these conserved charges and their algebra in a generic curved spacetime for a class of dynamical systems with the Hamiltonians quadratic and linear in momentum and spin.

We study analytically the branching ratio (BR) and charge parity (CP) asymmetries of the $\overline{B_s^0}\to K^{\ast 0}{\rho }^0$ and $K^{\ast 0}\omega$ decay modes within QCDF approach. We find the $\mathrm{\text{BR}}(\overline{B_s^0}\to K^{\ast 0}{\rho }^0)=(1.28\pm 0.23)\times 10^{-6}$ and $\mathrm{\text{BR}}(\overline{B_s^0}\to K^{\ast 0}\omega )=(1.12\pm 0.58)\times 10^{-6}$. We also find the values of CP asymmetries are ${{𝒜}}_{CP}^{\text{dir}}(\overline{B_s^0}\to K^{\ast 0}{\rho }^0)=0.214\pm 0.087$, ${{𝒜}}_{CP}^{\text{mix}}(\overline{B_s^0}\to K^{\ast 0}{\rho }^0)=0.377\pm 0.147$, ${{𝒜}}_{CP}^{\mathrm{\Delta }\mathrm{\Gamma }}(\overline{B_s^0}\to K^{\ast 0}{\rho }^0)=0.901\pm 0.051$, ${{𝒜}}_{CP}^{\text{dir}}(\overline{B_s^0}\to K^{\ast 0}\omega )=0.284\pm 0.038$, ${{𝒜}}_{CP}^{\text{mix}}(\overline{B_s^0}\to K^{\ast 0}\omega )=0.835\pm 0.024$, and ${{𝒜}}_{CP}^{\mathrm{\Delta }\mathrm{\Gamma }}(\overline{B_s^0}\to K^{\ast 0}\omega )=-0.471\pm 0.063$. The reported results are consistent with the recent theoretical predictions and can be used as a reference values in the forthcoming experiments.

We study the resonances $\varphi (1020)$ and $\varphi (1680)$ contributions for the three-body decays $B^{+}\to D_s^{+}K\bar{K}$ in the perturbative QCD approach. The branching ratios for $B^{+}\to D_s^{+}\varphi (1020)\to D_s^{+}{K}^{+}{K}^{-}$ and $B^{+}\to D_s^{+}\varphi (1020)\to D_s^{+}{K}^0{\bar{K}}^0$ are predicted to be $(1.53\pm 0.23)\times 10^{-7}$ and $(1.02_{-0.13}^{+0.19})\times 10^{-7}$, respectively. The decay $B^{+}\to D_s^{+}\varphi (1680)$ with $\varphi (1680)$ decays into $K^{+}{K}^{-}$ or $K^0{\bar{K}}^0$, has the branching fraction $(6.94_{-2.02}^{+1.83})\times 10^{-9}$, which is about $5\%$ of the result for $B^{+}\to D_s^{+}\varphi (1020)\to D_s^{+}{K}^{+}{K}^{-}$.

The source of the universe inflation is electromagnetic fields obeying rational nonlinear electrodynamics proposed earlier. Within this model the singularities of the electric field at the center of charges, the Ricci scalar, the Ricci tensor squared and the Kretschmann scalar are absent. We consider the universe which is filled by stochastic magnetic fields. It is demonstrated that the inflation lasts approximately $2$ s with the reasonable $e$-folding number $N\approx 63$. The inflation starts from de Sitter space–time and after the universe inflation end it decelerates approaching the radiation era.