Abstract
We present results for Drell-Yan production from the GENEVA Monte-Carlo framework. We combine the fully-differential NNLO calculation with higher-order resummation in the 0-jettiness resolution variable. The resulting parton-level events are further combined with parton showering and hadronization provided by PYTHIA8. The 0-jettiness resummation is carried out to NNLL', which consistently incorporates all singular virtual and real NNLO corrections. It thus provides a natural perturbative connection between the NNLO calculation and the parton shower regime, including a systematic assessment of perturbative uncertainties. In this way, inclusive observables are correct to NNLO, up to small power corrections in the resolution cutoff. Furthermore, the perturbative accuracy of 0-jet-like resummation variables is significantly improved beyond the parton shower approximation. We provide comparisons with LHC measurements of Drell-Yan production at 7 TeV from ATLAS, CMS, and LHCb. As already observed in $e^+e^-$ collisions, for resummation-sensitive observables, the agreement with data is noticeably improved by using a lower value of $\alpha_s(M_Z) = 0.1135$.
Highlights
There are several different ways to obtain theoretical predictions for collider processes involving strongly interacting particles, namely fixed-order (FO) perturbation theory, resummed perturbation theory, and predictions using parton shower (PS) algorithms.In FO perturbation theory, the perturbative expansion is carried out to a given order in the strong coupling constant αs
The above minimal leading logarithmic (LL) resummation is sufficient for our current purposes, where we focus on zero-jet resummation variables and inclusive observables and where we primarily need it to have a proper matching to the parton shower
We have presented a combination of the fully differential next-to-next-to leading order (NNLO) calculation for Drell-Yan production pp → γ=Z → lþl− combined with the NNLL0 resummation of 0jettiness and interfaced with the parton shower provided by PYTHIA8 within the GENEVA Monte Carlo framework
Summary
There are several different ways to obtain theoretical predictions for collider processes involving strongly interacting particles, namely fixed-order (FO) perturbation theory, resummed perturbation theory, and predictions using parton shower (PS) algorithms. Resummed perturbation theory allows one to systematically carry out the resummation beyond the LL or strongly ordered limit and is more accurate than parton showers. Combinations of specific Drell-Yan-like next-to-next-to-leading order (NNLO) calculations with parton showers have been presented in Refs. The primary goal is to improve the perturbative accuracy of parton shower Monte Carlo (MC) programs for inclusive FO observables, while the description of the resummation region is left to the parton shower This combination amounts to matching the FO calculation to the LL resummation in the parton shower’s resolution variable. We show that by including the higher-order resummation for T 0 as the resolution variable, the perturbative accuracy for other zero-jet-like observables in the resummation region is significantly improved, and our predictions agree well with dedicated higher-order resummed calculations.
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