Modern Physics Letters A

In this article we present a short review on measurements of charmonia production at the LHCb experiment carried out during 2010, 2011 and 2012 data taking periods. The review covers the production of J/ψ, ψ(2S), χ_c, J/ψJ/ψ, as well as J/ψ in association with open charm. We also review the measurement of J/ψ polarization. The results are compared to theoretical predictions.

In the CP-violating minimal supersymmetric extension of the Standard Model (MSSM), we study the two-loop diagrams without the one-loop self-energy, and they are composed of virtual neutralino–slepton-Z. We obtain electroweak corrections to the anomalous magnetic dipole moment (MDM) of muon. With electromagnetic gauge invariance, the Wilson coefficients of dimension-5 operators contributing to the MDM of muon are deduced. To remove the ultra-violet divergences induced by the divergent sub-diagrams, we use the on-shell scheme. The numerical results are about 8.8×10^-11, i.e. at the same order of present experimental precision, which indicates these two-loop diagrams are important.

Assuming that the leptonic mixing matrix is given in first approximation by the tribimaximal form or a generalization of this, we deduce some consequences with regard to the finite symmetries that may be applied in the minimal lepton sector of the electroweak theory.

We clarify in a quantitative way the impact that distinct chemical T_c and kinetic T_k freeze-out temperatures have on the reduction of the neutrino fugacity ϒ_ν below equilibrium, i.e. ϒ_ν<1, and the increase of the neutrino temperature T_ν via partial reheating. We establish the connection between ϒ_ν and T_k via the modified reheating relation T_ν(ϒ_ν)/T_γ, where T_γ is the temperature of the background radiation. Our results demonstrate that one must introduce the chemical nonequilibrium parameter, i.e. the fugacity, ϒ_ν, as an additional standard cosmological model parameter in the evaluation of CMB fluctuations as its value allows measurement of T_k.

In this paper we study the properties of Schwarzschild black hole surrounded by quintessence matter. The main objective of the paper is to show the existence of Nariai type black hole for special values of the parameters in the theory. The Nariai black hole with the quintessence has the topology dS₂ ×S₂ with dS₂ with a different curvature than what would be expected for the Schwarzschild–de Sitter degenerate black hole. Temperature and the entropy for the Schwarzschild–de Sitter black hole and the Schwarzschild-quintessence black hole are compared. The temperature and the curvature are computed for general values of the state parameter ω.

We study (2+1)-dimensional holographic superconductors in the presence of non-minimally coupled electromagnetic field to gravity by considering an arbitrary linear combination of RF²-type invariants with three parameters. Our analytical analysis shows that the non-minimal couplings affect the condensate and the critical temperature.