Oct 2021 - Sept 2022

# Internal seminar by Wanli Ju

Europe/London
Description

Title: Projected transverse momentum resummation in the top-antitop pair production at LHC

Abstract: In this work, the projected transverse momentum spectrum, i.e., $\mathrm{d}\sigma_{t\bar{t}}/\mathrm{d}q_{\tau}$  is investigated on the process $pp\to t\bar{t}+X$ and in particular, the low $q_{\tau}$ domain is laid stress on.  Here $q_{\tau}\equiv |\vec{q}_{\mathrm{T},t\bar{t}}\cdot \vec{\tau}|$ with $\tau$ denoting a unit reference vector on the transverse plane. We will demonstrate that in analogy to the azimuthally averaged distribution $\mathrm{d}\sigma_{t\bar{t}}/\mathrm{d}q_{\mathrm{T}}$, the leading power contribution of the distribution $\mathrm{d}\sigma_{t\bar{t}}/\mathrm{d}q_{\tau}$ is also all-perturbative-order independent of the asymptotic behaviors caused by the azimuthal correlations. This independence immediately leads to the applicability of the logarithmically exponentiating resummation scheme and this work will utilize the EFT-based (rapidity) renormalisation groups approach to accomplish this target. To validate the asymptotic expansion entailed during the derivation of the factorization formula,  we compare the Sherpa outputs with those from EFT,  observing the agreement in both NLO and N$^2$LO results in the limit $q_{\tau}\to0$~GeV. As to the resummed distributions, the results up to N$^2$LL precision have been evaluated and in comparison to NLL, the manifest decline in the uncertainty has been found out amongst the N$^2$LL curves.

Zoom link:  IPPP Seminars

https://durhamuniversity.zoom.us/j/99420124988?pwd=ZEFLSDB3THJtaWZOTU54R25mT1NuZz09

Meeting ID: 994 2012 4988