Importance of Nonperturbative QCD Parameters for Bottom Mesons

The importance of nonperturbative quantum chromodynamics (QCD) parameters is discussed in context to the predicting power for bottom meson masses and isospin splitting. In the framework of heavy quark effective theory, the work presented here focuses on the different allowed values of the two nonperturbative QCD parameters used in heavy quark effective theory formula, and using the best fitted parameter, masses of the excited bottom meson states in <math id="M1" xmlns="http://www.w3.org/1998/Math/MathML"><msup><mrow><mi>j</mi></mrow><mrow><mi>p</mi></mrow></msup><mo>=</mo><msup><mrow><mfenced separators="|"><mrow><mrow><mrow><mn>1</mn></mrow><mo>/</mo><mrow><mn>2</mn></mrow></mrow></mrow></mfenced></mrow><mrow><mo>+</mo></mrow></msup></math> doublet in strange and nonstrange sectors are calculated here. The calculated masses are found to be matching well with experiments and other phenomenological models. The mass splitting and hyperfine splitting have also been analyzed for both strange and nonstrange heavy mesons with respect to spin and flavor symmetries

Cardy-Verlinde Formula and Its Self-Gravitational Corrections for Regular Black Holes

We check the consistency of the entropy of Bardeen and Ayón Beato-García-Bronnikov black holes with the entropy of particular conformal field theory via Cardy-Verlinde formula. We also compute the first-order semiclassical corrections of this formula due to self-gravitational effects by modifying pure extensive and Casimir energy in the context of Keski-Vakkuri, Kraus and Wilczek analysis. It is concluded that the correction term remains positive for both black holes, which leads to the violation of the holographic bound

Null Geodesics and Strong Field Gravitational Lensing of Black Hole with Global Monopole

We study two interesting features of a black hole with an ordinary as well as phantom global monopole. Firstly, we investigate null geodesics which imply unstable orbital motion of particles for both cases. Secondly, we evaluate deflection angle in strong field regime. We then find Einstein rings, magnifications, and observables of the relativistic images for supermassive black hole at the center of galaxy NGC4486B. We also examine time delays for different galaxies and present our results numerically. It is found that the deflection angle for ordinary/phantom global monopole is greater/smaller than that of Schwarzschild black hole. In strong field limit, the remaining properties of these black holes are quite different from the Schwarzschild black hole

Eta Prime Gluonic Contribution to the Nucleon Self-Energy in an Effective Theory

We estimate a possible <math id="M1" xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="normal"/><msup><mrow><mi>η</mi></mrow><mrow><mi mathvariant="normal">′</mi></mrow></msup></math> gluonic contribution to the self-energy of a nucleon in an effective theory. The couplings of the topological charge density to nucleons give rise to OZI violating <math id="M2" xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="normal"/><msup><mrow><mi>η</mi></mrow><mrow><mi mathvariant="normal">′</mi></mrow></msup></math> -nucleon interactions. The one-loop self-energy of nucleon arising due to these interactions is studied using a heavy baryon chiral perturbation theory. The divergences have been removed using appropriate form factors. The nontrivial structure of the QCD vacuum has also been taken into account. The numerical results are sensitive to the choice of the regulator to a nonnegligible extent. We get the total contribution to the nucleon mass coming from its interaction with the topological charge density <math id="M3" xmlns="http://www.w3.org/1998/Math/MathML"><mi>δ</mi><msub><mrow><mi>m</mi></mrow><mrow><mtext>tot</mtext></mrow></msub><mo>≅</mo><mo>-</mo><mo stretchy="false">(</mo><mn>2.5</mn><mtext>–</mtext><mn>7.5</mn><mo stretchy="false">)</mo></math> % of the nucleon mass

Instability of meridional axial system in f ( R ) gravity

We analyze the dynamical instability of a non-static reflection axial stellar structure by taking into account the generalized Euler equation in metric f ( R ) gravity. Such an equation is obtained by contracting the Bianchi identities of the usual anisotropic and effective stress-energy tensors, which after using a radial perturbation technique gives a modified collapse equation. In the realm of the R+ϵRn gravity model, we investigate instability constraints at Newtonian and post-Newtonian approximations. We find that the instability of a meridional axial self-gravitating system depends upon the static profile of the structure coefficients, while f ( R ) extra curvature terms induce the stability of the evolving celestial body

Schwarzschild-de Sitter and Anti-de Sitter Thin-Shell Wormholes and Their Stability

This paper is devoted to construct Schwarzschild-de Sitter and anti-de Sitter thin-shell wormholes by employing Visser’s cut and paste technique. The Darmois-Israel formalism is adopted to formulate the surface stresses of the shell. We analyze null and weak energy conditions as well as attractive and repulsive characteristics of thin-shell wormholes. We also explore stable and unstable solutions against linear perturbations by taking two different Chaplygin gas models for exotic matter. It is concluded that the stress-energy tensor components violate the null and weak energy conditions indicating the existence of exotic matter at the wormhole throat. Finally, we find unstable and stable configurations for the constructed thin-shell wormholes

Warm anisotropic inflationary universe model

This paper is devoted to the study of warm inflation using vector fields in the background of a locally rotationally symmetric Bianchi type I model of the universe. We formulate the field equations, and slow-roll and perturbation parameters (scalar and tensor power spectra as well as their spectral indices) in the slow-roll approximation. We evaluate all these parameters in terms of the directional Hubble parameter during the intermediate and logamediate inflationary regimes by taking the dissipation factor as a function of the scalar field as well as a constant. In each case, we calculate the observational parameter of interest, i.e., the tensor–scalar ratio in terms of the inflaton. The graphical behavior of these parameters shows that the anisotropic model is also compatible with WMAP7 and the Planck observational data

Study of inflationary generalized cosmic Chaplygin gas for standard and tachyon scalar fields

We consider an inflationary universe model in the context of the generalized cosmic Chaplygin gas by taking the matter field as standard and tachyon scalar fields. We evaluate the corresponding scalar fields and scalar potentials during the intermediate and logamediate inflationary regimes by modifying the first Friedmann equation. In each case, we evaluate the number of e-folds, scalar as well as tensor power spectra, scalar spectral index, and the important observational parameter, the tensor–scalar ratio in terms of inflation. The graphical behavior of this parameter shows that the model remains incompatible with WMAP7 and Planck observational data in each case

Stability of regular energy density in Palatini f(R) gravity

The present work explores the effects of the three-parametric f(R) model on the stability of the regular energy density of planar fluid configurations with the Palatini f(R) formalism. For this purpose, we develop a link between the Weyl scalar and structural properties of the system by evaluating a couple of differential equations. We also see the effects of Palatini f(R) terms in the formulation of structure scalars obtained by orthogonal splitting of the Riemann tensor in general relativity. We then identify the parameters which produce energy density irregularities in expansive and expansion-free dissipative as well as non-dissipative matter distributions. It is found that particular combinations of the matter variables lead to irregularities in an initially homogeneous fluid distribution. We conclude that Palatini f(R) extra corrections tend to decrease the inhomogeneity, thereby imparting stability to the self-gravitating system

Observation of Electromagnetic Dalitz decays J/ψ\to P e^+e^-

Based on a sample of (225.3\pm2.8)\times 10^{6} J/\psi events collected with the BESIII detector, the electromagnetic Dalitz decays of J/\psi \to P e^+e^-(P=\eta'/\eta/\pi^0) are studied. By reconstructing the pseudoscalar mesons in various decay modes, the decays J/\psi \to \eta' e^+e^-, J/\psi \to \eta e^+e^- and J/\psi \to \pi^0 e^+e^- are observed for the first time. The branching fractions are determined to be \mathcal{B}(J/\psi\to \eta' e^+e^-) = (5.81\pm0.16\pm0.31)\times10^{-5}, \mathcal{B}(J/\psi\to \eta e^+e^-) = (1.16\pm0.07\pm0.06)\times10^{-5}, and \mathcal{B}(J/\psi\to \pi^0 e^+e^-)=(7.56\pm1.32\pm0.50)\times10^{-7}, where the first errors are statistical and the second ones systematic