Angular distributions in $t{\bar t}H (H\rightarrow b\bar{b})$ reconstructed events at the LHC

TL;DR

This paper investigates angular distributions in $t\bar{t}H$ events at 13 TeV LHC to enhance signal-background discrimination using fully reconstructed dileptonic final states.

Contribution

It introduces new angular observables and asymmetries in $t\bar{t}H$ events that improve separation from the main background after full event reconstruction.

Findings

Angular distributions differ significantly between signal and background.

Proposed asymmetries enhance discrimination power.

Reconstruction preserves key angular features for analysis.

Abstract

The associated production of a Higgs boson and a top-quark pair, $t{\bar t} H$, in proton-proton collisions is addressed in this paper for a center of mass energy of 13TeV at the LHC. Dileptonic final states of $t{\bar t}H$ events with two oppositely charged leptons and four jets from the decays $t\rightarrow bW^+ \rightarrow b \ell^+\nu_\ell$, $\bar{t}\rightarrow \bar{b}W^- \rightarrow \bar{b} \ell^-\bar{\nu}_\ell$ and $h\rightarrow b\bar{b}$, are used. Signal events, generated with MadGraph5_aMC@NLO, are fully reconstructed by applying a kinematic fit. New angular distributions of the decay products as well as angular asymmetries are explored in order to improve discrimination of $t{\bar t} H$ signal events over the dominant irreducible background contribution, $t{\bar t}b{\bar b}$. Even after the full kinematic fit reconstruction of the events, the proposed angular distributions and asymmetries are still quite different in the $t\bar{t}H$ signal and the dominant background ($t\bar{t}b\bar{b}$).