Kinematic Discrimination of tW and tt Productions Using Initial State Radiation

TL;DR

This paper explores how to distinguish single top quark production in association with a W boson from top pair production using specific kinematic variables, enhancing detection accuracy.

Contribution

It introduces a method employing M_T2 and invariant mass variables to effectively separate tW+j from tt production with high purity.

Findings

tW+j can be distinguished from tt with high purity

Kinematic variables like M_T2 improve signal-background separation

Method reduces statistical cost for identifying tW production

Abstract

Production of a single top quark provides excellent opportunity for understanding top quark physics and Cabibbo-Kobayashi-Maskawa structure of the quark sector in the Standard Model. Although an associated production with a b-quark has already been observed at the Tevatron in 2009, a single top production in association with a W gauge boson has not been observed till 2014 at the LHC, where pair production of the top quark serves as the dominant background. Due to the kinematic similarity between tW and the dominant background, it is challenging to find suitable kinematic variables that offer good signal-background separation, which naturally leads to the use of multivariate methods. In this paper, we investigate kinematic structure of tW+j channel using M_T2 and invariant mass variables, and find that tW +j production could well be separated from tt production with high purity at a low cost of statistics when utilizing these kinematic correlations.