What does the W transverse momentum distribution say about the W+1 jet/W+0 jet ratio?

Abstract

We compute the W transverse momentum distribution at large transverse momentum at fixed next-to-leading order (i.e. O(alpha_s^2) and find good agreement with the preliminary measurements reported by D0. We find that the W transverse momentum distribution is typically significantly larger than the exclusive one-jet rate for a given value of p_T^W or E_T^jet, mainly because two or more jet events are excluded. As a consequence, we find that theoretically the W+1 jet to W+0 jet ratio R^10 is smaller than the analogous quantity defined in terms of p_T^W, R^W. This hierarchy is preserved under changes of renormalisation/factorisation scales, strong coupling constant and jet algorithm. However, this appears to be in contradiction with the preliminary experimental results which suggest R^10 > R^W.