A Combination of CDF and D0 limits on the branching ratio of B0(s)(d) ---> mu+ mu- decays

The authors combine the results of CDF and D0 searches for the rare decays B{sub s}{sup 0} {yields} {mu}{sup +}{mu}{sup -} and B{sub d}{sup 0} {yields} {mu}{sup +}{mu}{sup -}. The experiments use 364 pb{sup -1} and 300 pb{sup -1} of data respectively. The limits on the branching ratios are obtained by normalizing the estimated sensitivity to the decay B{sup +} {yields} J/{psi}K{sup +} taking into account the fragmentation ratios f{sub u}/f{sub s(d)}. The combined results exclude branching ratios of BR(B{sub s}{sup 0} {yields} {mu}{sup +}{mu}{sup -}) > 1.5 x 10{sup -7} and BR(B{sub d}{sup 0} {yields} {mu}{sup +}{mu}{sup -}) > 4.0 x 10{sup -8} at 95% confidence level. These are the most stringent limits on these decays at the present time.