Semileptonic charmed B meson decays in universal extra dimension model
Abstract
The present study focuses on the semileptonic B_{c}→D_{s}^{*}l^{+}l^{} (l=μ, τ) decay in the standard model (SM) and in the universal extra dimension (UED) model. In addition to the contribution from the flavor changing neutral current (FCNC) transitions the weak annihilation (WA) contribution is also important for this decay. It is found that the WA gives 6.7 times larger branching ratio than the penguin contribution for the decay B_{c}→D_{s}^{*}μ^{+}μ^{}. The contribution from the WA and FCNC transitions are parametrized in terms of the form factors. In this work we first relate the form factors through Ward identities and then express them in terms of g_{+}(0) which is extracted from the decay B_{c}→D_{s*}γ through the QCD sum rules approach. These form factors are then used to analyze the physical observables such as branching ratio and helicity fractions of the final state D_{s}^{*} meson in the SM. This analysis is then extended to the UED model where the dependency of the above mentioned physical observables to the compactification radius R, the only unknown parameter in the UED model, is studied. It is shown that the helicity fractions of D_{s}^{*} are sensitive to the UED model especially when we have muons as the final state lepton. This sensitivity is marked up at the low q^{2} region, irrespective of the choice of the form factors. It is hoped that in the next couple of years the LHC will provide enough data on the B_{c}→D_{s}^{*}l^{+}l^{} channel; therefore, these helicity fractions serve as a useful tool to establish new physics predicted by the UED model.
 Publication:

Physical Review D
 Pub Date:
 August 2011
 DOI:
 10.1103/PhysRevD.84.035003
 arXiv:
 arXiv:1101.2323
 Bibcode:
 2011PhRvD..84c5003P
 Keywords:

 13.20.He;
 Decays of bottom mesons;
 High Energy Physics  Phenomenology
 EPrint:
 17 pages, 4 figures