Slepton production as a probe of the squark mass scale

Abstract

We investigate an important radiative correction to the slepton and chargino production processes. We consider a supersymmetric spectrum with a large splitting between the squark and slepton masses. In this case, in the effective theory below the squark mass threshold, the supersymmetric Slavnov-Taylor identities which enforce the equality of the gauge and gaugino couplings are violated. The gaugino propagators receive potentially large corrections due to virtual quark or squark loop effects. We compute the full one-loop (s)quark corrected slepton production cross sections. The $t$-channel one-loop scattering amplitudes are factorized into an effective chargino-neutralino mass matrix and an effective fermion-sfermion-gaugino coupling. The difference between the effective gaugino coupling and the gauge coupling is proportional to $\mathrm{ln}{(M}_{\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{Q}}{/m}_{\mathcal{l}\ifmmode \tilde{}\else \~{}\fi{}})$ in the large squark mass limit. We find that the one-loop corrected slepton production cross sections can depend on the squark mass strongly, up to $9%\ifmmode\times\else\texttimes\fi{}{\mathrm{log}}_{10}{(M}_{\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{Q}}{/m}_{\mathcal{l}\ifmmode \tilde{}\else \~{}\fi{}})$. We investigate the squark mass sensitivity of the slepton cross-section measurements at a future linear collider. For sneutrino production accessible at $\sqrt{s}=500$ GeV there can be sensitivity to squark masses at or larger than 1 TeV.