5 research outputs found
Leading logarithmic QCD corrections to the B_s --> \gamma \gamma decays in the two Higgs doublet model
We calculate the leading logarithmic QCD corrections to the decay B_s -->
\gamma \gamma in the two Higgs doublet model (2HDM) including O_7 type long
distance effects and estimate the restrictions of the 2HDM parameters, tan\beta
and m_H, using the experimental data of B --> X_s \gamma decay provided by the
CLEO collaboration. A lower bound for the charged Higgs mass m_H as a function
of the renormalization scale \mu is given for 2HDM model II. We further present
the dependencies of the branching ratio Br(B_s --> \gamma \gamma) and the ratio
|A^{+}|^2/|A^{-}|^2 on m_H and tan\beta including leading logarithmic QCD
corrections. The dependence on the renormalization scale is found to be strong
for both ratios. An additional uncertainty arises from the variation of the
parameters of the bound state model, (m_b, \bar{\Lambda}_s). We see, that to
look for charged Higgs effects the measurement of the branching ratio Br(B_s
--> \gamma \gamma) is promising.Comment: 25 pages, 19 figures (required epsf.sty
Planejamento integrado de uso da terra: uma disciplina integradora no ensino da agronomia na UFRGS
Plasma lipid profiles discriminate bacterial from viral infection in febrile children
Fever is the most common reason that children present to Emergency Departments. Clinical signs and symptoms suggestive of bacterial infection ar