Semileptonic decay of BcB_c meson into ccˉc\bar c states in a QCD potential model

The slope and curvature of Isgur Wise function for $B_{c}$ meson is computed in a QCD potential model in two different approaches of choosing the perturbative term of the Cornell potential. Based on heavy quark effective theory the exclusive semileptonic decay rates of $B_c$ meson into the $c\bar c\ (\eta_c,J/\psi)$states are exploited. Spin symmetry breaking effects are ignored upto a particular point and the form factors are connected with Isgur-Wise function for other kinematic point since the recoil momentum of$c\bar c$from$B_{c}$ is small due to its heavy mass.Comment: 13 pages, 4 tables, 4 figures,Accepted to Int.J.Mod.Phys.

Dynamics of coupled phantom and tachyon fields

In this paper, we apply the dynamical analysis to a coupled phantom field with scaling potential taking particular forms of the coupling (linear and combination of linear), and present phase space analysis. We investigate if there exist late time accelerated scaling attractor that has the ratio of dark energy and dark matter densities of the order one. We observe that the scrutinized couplings cannot alleviate the coincidence problem, however acquire stable late time accelerated solutions. We also discuss coupled tachyon field with inverse square potential assuming linear coupling.Comment: 16 pages, 6 caption figures, 3 Tables, text, figure are added, matches with the published versio