The effects of O(α²) initial state QED corrections to e⁺e⁻ → γ$^{⁎}$/Z$^{⁎}$ at very high luminosity colliders

J. Blümlein, A. De Freitas, C.G. Raab, K. Schönwald
We present numerical results on the recently completed O (α 2 ) initial state corrections to the process e + 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 the Z -boson, the Higgs boson, and the top quark. We observe differences to an earlier result [1] in the non-logarithmic contributions at O (α 2 ). The new result leads to a 4 MeV shift in the Z width considering the lower end s 0 = 4m 2
more » ... ower end s 0 = 4m 2 τ of the radiation region, which is larger than the present accuracy. A corresponding cut to s 0 /s = 0.01 only implies a shift of 0.2 MeV. We present predictions on the radiative corrections to the central processes e + e − → γ * /Z * , e + e − → Z H and e + e − → tt planned at future colliders like the ILC, CLIC, FCC_ee and CEPC to measure the mass and the width of the Z boson, the Higgs boson and the top quark, for which the present corrections are significant.
doi:10.5445/ir/1000105520 fatcat:cir2qd6blvhtbl2o45qrrvmpou