Final charged-lepton angular distribution and possible anomalous top-quark couplings in p p -> t tbar X -> l^+ X'

TL;DR

This paper investigates how potential nonstandard top-quark interactions affect the angular distribution of final charged leptons in proton-proton collisions at the LHC, using effective operators and optimal-observable analysis.

Contribution

It calculates the charged-lepton angular distribution considering anomalous top couplings and applies optimal-observable techniques to estimate measurement uncertainties.

Findings

Derived angular distribution with nonstandard couplings

Applied optimal-observable method for uncertainty estimation

Provided insights into detecting anomalous top interactions

Abstract

Possible anomalous (or nonstandard) top-quark interactions with the gluon and those with the W boson induced by SU(3) x SU(2) x U(1) gauge-invariant dimension-6 effective operators are studied in p p -> t tbar X -> l^+ X' (l=e or mu) at the Large Hadron Collider (LHC). The final charged-lepton (l^+) angular distribution is first computed for nonvanishing nonstandard top-gluon and top-W couplings with a cut on its transverse momentum. The optimal-observable procedure is then applied to this distribution in order to estimate the expected statistical uncertainties in measurements of those couplings that contribute to this process in the leading order.