Modern Physics Letters A

We consider the scalar gravity theory in (2 + 1) dimensions and find a black hole solution. We show that this approach does not lead to a Newtonian limit except for special metric configurations.

Motivated by the 3.2σ(1.4σ) deviations between the recent experimental value for and the standard model (SM) prediction, we examine the effect of new physics (NP) on the couplings and . First we focus our attention on the dynamical models. Then, using effective Lagrangian techniques, we discuss the corrections of NP to and . We find some kinds of NP which might explain the recently experimental data about R_b and . However, the free parameters of these kinds of NP must be severely constrained.

The Sp(3) BRST symmetry for Yang–Mills theory is derived in the framework of the antibracket–antifield formalism.

(2 + 1)-dimensional Georgi–Glashow model is explored in the regime when the Higgs boson is not infinitely heavy, but its mass is of the same order of magnitude as the mass of the W-boson. In the weak-coupling limit, the Debye mass of the dual photon and the expression for the monopole potential are found. The cumulant expansion applied to the average over the Higgs field is checked to be convergent for the known data on the monopole fugacity. These results are further generalized to the SU(N)-case. In particular, it is found that the requirement of convergence of the cumulant expansion establishes a certain upper bound on the number of colors. This bound, expressed in terms of the parameter of the weak-coupling approximation, allows the number of colors to be large enough. Finally, the string tension and the coupling constant of the so-called rigidity term of the confining string are found at arbitrary number of colors.

In view of the recently reported evidence for a nonzero Majorana mass of the electron neutrino, together with the established phenomena of atmospheric and solar neutrino oscillations, the case of three nearly mass-degenerate Majorana neutrinos is now an interesting possibility. We show in this paper how a natural pattern of symmetry breaking in the recently proposed A₄ model of Majorana neutrino masses can accommodate the data on neutrino oscillations, resulting in the predictions sin² 2θ_atm = 1 and sin² 2θ_sol = 2/3.

In this paper it is shown that the present accelerated expansion of the Universe can be explained only by considering variation of the speed of light, without taking into account the cosmological constant or quintessence matter.

Two forms are available for the fermion propagator at finite temperature and density. It is shown that, when one deals with a diquark-condensation-operator inserted Green function in hot and dense QCD, the standard form of the quark propagator does not work. On the other hand, another form of the quark propagator does work.