Chargino mass determination at a muon collider

Abstract

We analyze the prospects at a muon collider for measuring chargino masses in the $\hat{I}{¼}^{+}\hat{I}{¼}^{-}\to \tilde{\ddot{I}}{‡}^{+}\tilde{\ddot{I}}{‡}^{-}$ process in the threshold region. We find that for the lighter chargino of a mass $100-200$ GeV, a measurement better than $50-300$ MeV should be possible with 50 fb${}^{-1}$ integrated luminosity. The accuracy obtained here is better than with other techniques or at other facilities. The muon sneutrino mass, which enters through the $\tilde{\hat{I}}{½}_{\hat{I}}¼$ exchange diagram, can also be simultaneously measured to a few GeV if it is not too heavy.

13 pages, 3 figures