Coherent Pair Creation from Beam - Beam - Interaction

. Abstract It has recently been recognized that in future linear colliders, there is a finite probability that the beamstrahlung photons will turn into e+epairs induced by the same beam-beam field, and this would potentially cause background problems. In this paper, we first review the probability of such a coherent pair creation process. It is seen that the constraint on the beamstrahlung parameter, T, is tight if these coherent pairs are to be totally suppressed. We then point out that there exists a minimum energy for the pair-created particles, which scales as N 1/5T. When combining this condition with the deflection angle for the low-energy particles, the contraint on the allowable ‘Y value is much relaxed. Finally, we calculate the effective cross section for producing the weak bosons by the low-energy e+epairs. It is shown that these cross sections are substantial for T > 1. We suggest that this effect -can help to autoscan the particle spectrum in the high energy frontier.