The effects of O( α 2) initial state QED corrections to e + e ??→? γ ?/ Z ? at very high luminosity colliders

摘要

We present numerical results on the recently completedO(α2)initial state corrections to the processe+e?→γ?/Z?, which is a central process at past and future high energy and high luminosity colliders for precision measurements of the properties of theZ-boson, the Higgs boson, and the top quark. We observe differences to an earlier result in the non-logarithmic contributions atO(α2). The new result leads to a 4 MeV shift in theZwidth considering the lower ends0=4mτ2of the radiation region, which is larger than the present accuracy. A corresponding cut tos0/s=0.01only implies a shift of 0.2 MeV. We present predictions on the radiative corrections to the central processese+e?→γ?/Z?,e+e?→ZHande+e?→tt￣planned at future colliders like the ILC, CLIC, FCC_ee and CEPC to measure the mass and the width of theZboson, the Higgs boson and the top quark, for which the present corrections are significant.