Vector leptoquark mass limits and branching ratios of KL0,B0,Bs → li+lj− decays with account of fermion mixing in leptoquark currents

The contributions of the vector leptoquarks of Pati–Salam type to the branching ratios of KL0,B0,B s → ll′ decays are calculated with account of the fermion mixing in the leptoquark currents of the general type. Using the general parametrizations of the mixing matrices the lower vector leptoquark mass limit mV > 86 TeV is found from the current experimental data on these decays. The branching ratios of the decays B0,B s → ll′ predicted at mV = 86 TeV are calculated. These branching ratios for the decays B0,B s → μ+μ−,eμ are close to the experimental data whereas those for the decays B0 → e+e−,eτ,μτ and Bs → e+e− are by order of 2–4 less than their current experimental limits. For the decays Bs → eτ,μτ these branching ratios are of orders 10−10 and 10−9, respectively. The predicted branching ratios will be useful in the current and future experimental searches for these decays.