Multiple-photon effects in asymmetries: μμ¯ vsbb¯

We present an analysis of the effects of multiple-photon emission, in the context of ${\mathit{Z}}^0$ physics at the SLAC Linear Collider and the CERN ${\mathit{e}}^{+}$ ${\mathit{e}}^{\mathrm{-}}$ collider LEP, on the forward-backward, left-right, and polarized forward-backward asymmetries for ${\mathit{e}}^{+}$ ${\mathit{e}}^{\mathrm{-}}$→${\mathrm{\mu }}^{+}$ ${\mathrm{\mu }}^{\mathrm{-}}$+n(γ) and ${\mathit{e}}^{+}$ ${\mathit{e}}^{\mathrm{-}}$→bb¯+n(γ). We focus on this ${\mathit{Z}}^0$-physics scenario in the presence of detector cuts. Realistic calculations are carried out with our Monte Carlo–based Yennie-Frautschi-Suura event-by-event approach to ${\mathrm{SU}}_{2\mathit{L}}$×${\mathrm{U}}_1$ radiative corrections at high energies. We conclude that the multiple-photon effects should be taken into account for high-precision ${\mathit{Z}}^0$ physics. We find further that, for high-luminosity unpolarized ${\mathit{Z}}^0$ physics, the bb¯+n(γ) final state looks much more promising as a way to measure the respective forward-backward asymmetry when it is compared to ${\mathrm{\mu }}^{+}$ ${\mathrm{\mu }}^{\mathrm{-}}$+n(γ) insofar as radiative corrections are concerned.