Speaker
Description
We present the resummed predictions for inclusive cross section for Drell-Yan and Higgs boson production at next-to-next-to leading logarithmic (\bar{NNLL}) accuracy taking into account both soft-virtual (SV) and next-to SV (NSV) threshold logarithms. We restrict ourselves to resummed contributions only from the diagonal channels for both the processes. We derive the N-dependent coefficients and the N-independent constants in Mellin-N space for our study. Using the minimal prescription we perform the inverse Mellin transformation and match it with the corresponding fixed order results. We report in detail the numerical impact of N-independent part of resummed result and explore the ambiguity involved in exponentiating them for both the processes. In the case of Higgs Boson production, by studying the K factors at different logarithmic accuracy, we find that the perturbative expansion shows better convergence improving the reliability of the prediction at NNLO + \bar{NNLL} accuracy. We also observe that the resummed SV + NSV result improves the renormalisation scale uncertainty at every order in perturbation theory. The uncertainty from the renormalisation scale ranges between (+8.85%, −10.12%) at NNLO whereas it goes down to (+6.54%, −8.32%) at NNLO + \bar{NNLL} accuracy. However, the factorisation scale uncertainty is worsened by the inclusion of these NSV logarithms hinting the importance of resummation beyond NSV terms for Higgs Boson case. For Drell-Yan production, we find that the resummation, taking into account the NSV terms, appreciably increases the cross section while decreasing the sensitivity to renormalisation scale. We observe that, at 13 TeV LHC energies, the SV+NSV resummation at \bar{NLL}(\bar{NNLL}) gives about 8% (2%) corrections respectively to the NLO (NNLO) results for the considered Q range: 150-3500 GeV. In addition, the absence of quark gluon initiated contributions to NSV part in the resummed terms leaves large factorisation scale dependence indicating their importance at NSV level. Finally, we present our predictions for SV+NSV resummed result at different collider energies for both the processes.
