Effects of isospin violation in the e+e− → B(*)$$ \overline{B} $$(*) cross sections

Abstract

Abstract Model estimates are obtained for the influence of Coulomb effects on the ratio of the cross sections for the production of charged and neutral B$$ \overline{B} $$ B ¯ and B*$$ \overline{B} $$ B ¯ * pairs in e+e− annihilation. It is shown that the difference between the masses of charged and neutral mesons obtained under the assumption that this ratio is constant on a scale of the order of the beam energy spread can differ from the true one by δM ∼ 0.03 MeV at the energy of Υ(5S) and by δM ∼ 0.4 MeV at the energy of Υ(4S). Thus, the errors given in the PDG for the difference between the masses of charged and neutral B mesons, based on the results obtained at the energy of Υ(4S), are strongly underestimated. Similar measurements at the energy of Υ(5S) will have an order of magnitude smaller systematic shift for the mass difference. This circumstance should be taken into account when planning future experiments at the B factory in KEK.