A ‘beauty factory’ is (in particle physics) a high-luminosity electron–positron collider dedicated to the study of the e+e → B⁰B̅⁰ process. Its centre of mass energy is at the ϒ(4¹S₃) resonance, namely at 10 580 MeV. This is only 20 MeV above the sum of the masses of the two Bs. Usually, in a collider the energies of the two beams are equal. However, in such a configuration the two Bs are produced with very low energies. They travel distances that are too small to be measured. Therefore, the beauty factories are asymmetric. Consider PEP2 at SLAC, where the electron momentum is p_e– = 9 GeV and the positron momentum is p_e+ = 3 GeV. Consider the case in which the two Bs are produced with the same energy. Find the distance travelled by the Bs in a lifetime and the angles of their directions to the beams.