Bound on minimal universal extra dimensions fromB¯→Xsγ

Abstract

We reexamine the constraints on universal extra dimensional models arising from the inclusive radiative $\overline{B}\ensuremath{\rightarrow}{X}_{s}\ensuremath{\gamma}$ decay. We take into account the leading order contributions due to the exchange of Kaluza-Klein modes as well as the available next-to-next-to-leading order corrections to the $\overline{B}\ensuremath{\rightarrow}{X}_{s}\ensuremath{\gamma}$ branching ratio in the standard model. For the case of one large flat universal extra dimension, we obtain a lower bound on the inverse compactification radius $1/R>600\text{ }\text{ }\mathrm{GeV}$ at 95% confidence level that is independent of the Higgs mass.