High Energy Physics Seminars

Electronic top tagger in CMS

by Dr. Debarati Roy (DHEP, TIFR)

Monday, December 21, 2020 from to (Asia/Kolkata)
Description
Based on a recently published paper [JHEP 01 (2020) 170], a method is proposed in the CMS experiment to identify jets which consist of the visible decay products of a boosted top quark decaying semileptonically with an electron in the final state. The overlap of electron shower with the particles from b quark hadronization makes the identification of the electrons difficult in such a scenario. Also a non-trivial amount of energy carried away by the invisible neutrino makes the identification of top quarks decaying semileptonically more challenging. The proposed method starts with a large radius jet and utilizes its energy composition, spatial distribution of the constituents of the jet, and the soft drop mass. The performance of the method is significantly improved by an explicit use of electrons in the jet and the addition of the variables which are particularly sensitive to electron shower shape or to the distance that an electron travels with respect to a secondary vertex in the jet. The proposed method is shown to offer a better performance as compared to the isolation variable presently used in the CMS analysis to reject jets from light quarks or gluons. The variables used in this method as well as the response of the classifier, which is the output of the method, are well modeled in data.