Scale setting and resummation of logarithms in pp -> V + jets

Abstract

The production of vector bosons in association with jets contains at least two unrelated scales. The first is the mass of the vector boson m_V and the second is the hard interaction scale giving rise to large transverse momenta of the produced jets. The production cross sections depend logarithmically on the ratio of these scales, which can lead to a poor convergence in fixed order perturbation theory. We illustrate how to resum all leading logarithmic terms using effective theory methods, and show that they can be resummed by a simple choice of the factorization scale. Implementing this scale choice we show that the large discrepancies between next-to-leading calculations and leading order calculations using more traditional choices of scales disappear.

Figures (9)

• Figure 1: $p_T$ distribution for the jet in the $pp\to W^++j$ process, both at leading order (dashed) and next-to-leading order (solid).
• Figure 2: Feynman diagrams contributing to the process $pp\to W^++j$.
• Figure 3: Matching of the amplitude for the partonic subprocess $qq \to Vg$. A similar relation holds for $qg \to Vq$
• Figure 4: Matching of the forward scattering matrix element for the partonic subprocess $qq \to Vg$. A similar relation holds again for $qg \to Vq$
• Figure 5: Sample Feynman diagrams for initial-state radiation and final-state radiation contributions to $pp \to V + 2$ jets.