Modern Physics Letters A

The status of top–bottom–tau Yukawa coupling unification in supersymmetric SO(10) models is reviewed with a particular emphasis on the implications of the Higgs boson mass in the vicinity of 125 GeV, as suggested by the Large Hadron Collider (LHC) Higgs data. In addition, the recently proposed model with negative μ, D-term splitting of the soft scalar masses and nonuniversal gaugino masses generated by a nonzero F-term in a 24-dimensional representation of SU(5) ⊂ SO(10) is reanalyzed in the context of the 125 GeV Higgs. The condition of top–bottom–tau Yukawa unification together with the Higgs mass of about 125 GeV impose strong lower mass limits on supersymmetry (SUSY) particles. Nevertheless, some of the Minimal Supersymmetric Standard Model (MSSM) particles may be within the reach of LHC. In the case of models with positive μ this is the gluino. While in the case of negative μ these are the pseudoscalar Higgs, the lighter sbottom (sometimes strongly degenerate with LSP leading to sbottom coannihilations), the right-handed down squark and the gluino.

In this work, we study the radiative leptonic decays of B^-, D^- and , including both the short-distance and long-distance contributions. The short-distance contribution is calculated by using the relativistic quark model, where the bound state wave function we used is that obtained in the relativistic potential model. The long-distance contribution is estimated by using vector meson dominance model.

5D cosmological model with 3-brane with matter is considered. The brane divides the bulk in two AdS half-spaces. Geometry of the model can be described by two types of coordinate systems: in the first setting the metric is static and the brane is moving in the bulk, in the second approach the metric is time-dependent and the brane is located at a fixed position in the bulk. Coordinate transformation connecting two coordinate systems is constructed.

The string corrections to the Riemann curvature tensor are found to first-order in the string slope parameter. This is done for D = 10, N = 1 supergravity, the presumed low energy limit of string theory. We then use a related constraint and proceed to find a third-order solution.

Recently several developments have taken place in the lattice QCD calculations of hadronic factors in the case of and the mixings along with contribution of the long distance effects in the system. These have led some authors (Refs. 12 and 13) to point towards the possibility of New Physics (NP) in these systems to the tune of 20% or so. However, the present analysis, based on essentially NP free inputs and incorporating constraints of unitarity, shows that in case the NP effects are there in the parameters associated with these systems, e.g. sin 2β, V_td, ϵ_K, etc., these seem to be only at a few percent level.

We show how SU(2) N_f = 4 Seiberg–Witten prepotentials are derived from four-point conformal blocks via considering Langlands duality.

This paper presents a new higher derivative gravity which in spontaneous breaking electroweak symmetry state does not have ghost in gravity sector. We show that Newton constant of the gravity and dark energy density depend on the fundamental TeV scale and the coupling constant at the quadratic curvature term. We consider the supersymmetric extension of this model.

We study a dependence of Green's functions for the Curci–Ferrari model on the parameter resembling the gauge parameter in massless Yang–Mills theories. It is shown that the on-shell generating functional of vertex functions (effective action) depends on this parameter.