5 research outputs found
Production of charged meson in bottom hadron charmed decays and the effect of the finite width correction of the meson
We calculate the branching ratio of a bottom hadron decaying into a charmed
hadron and a charged meson within the QCD factorization approach. We
consider the effect of the finite width correction of the meson. Our
numerical calculation shows an obvious correction because of this effect. We
find that the finite width effect of the meson reduces the branching
ratios by about 9% to 11% for bottom meson decay channels:
, , and , and
increases the branching ratio by about 10% for
.Comment: 12 page
Shear Viscosities from the Chapman-Enskog and the Relaxation Time Approaches
The interpretation of the measured elliptic and higher order collective flows
in heavy-ion collisions in terms of viscous hydrodynamics depends sensitively
on the ratio of shear viscosity to entropy density. Here we perform a
quantitative comparison between the results of shear viscosities from the
Chapman-Enskog and relaxation time methods for selected test cases with
specified elastic differential cross sections: (i) The non-relativistic,
relativistic and ultra-relativistic hard sphere gas with angle and energy
independent differential cross section (ii) The Maxwell gas, (iii) chiral pions
and (iv) massive pions for which the differential elastic cross section is
taken from experiments. Our quantitative results reveal that (i) the extent of
agreement (or disagreement) depends sensitively on the energy dependence of the
differential cross sections employed, and (ii) stress the need to perform
quantum molecular dynamical (URQMD) simulations that employ Green-Kubo
techniques with similar cross sections to validate the codes employed and to
test the accuracy of other methods.Comment: To be submitted to PR