Improved sensitivity to charged Higgs searches in top quark decays t→bH +→b(τ + ν τ ) at the LHC using τ polarisation and multivariate techniques

Abstract

We present an analysis with improved sensitivity to the light charged Higgs (m H + < m t − m b ) searches in the top quark decays t → bH + → b(τ + ν τ ) + c.c. in the tt and single t/t production processes at the LHC. In the Minimal Supersymmetric Standard Model (MSSM), one anticipates the branching ratio B(H + → τ + ν τ ) 1 over almost the entire allowed tan β range. Noting that the τ + arising from the decay H + → τ + ν τ are predominantly rightpolarized, as opposed to the τ + from the dominant background W + → τ + ν τ , which are left-polarized, a number of H + /W + → τ + ν τ discriminators have been proposed and studied in the literature. We consider hadronic decays of the τ ± , concentrating on the dominant one-prong decay channel τ ± → ρ ± ν τ . The energy and p T of the charged prongs normalised to the corresponding quantities of the ρ ± are convenient variables which serve as τ ± polariser. We use the distributions in these variables and several other kinematic quantities to train a boosted decision tree (BDT). Using the BDT classifier, and a variant of it called BDTD, which makes use of decorrelated variables, we have calculated the BDT(D)-response functions to estimate the signal efficiency vs. the rejection of the background. We argue that this chain of analysis has a high sensitivity to light charged Higgs searches up to a mass of 150 GeV in the decays t → bH + (and charge conjugate) at the LHC. For the case of single top production, we also study the transverse mass of the system determined using Lagrange multipliers. a

Heavy Higgs bosons at 14 TeV and 100 TeV

“…then seen a large adoption especially in the experimental community, including [67][68][69][70][71]. For a short introduction see [72].…”

Searching for heavy charged Higgs boson with jet substructure at the LHC

“…TMVA methods have been broadly used in the top quark precision measurements by experimental collaborations [57,58,59] and W-jet substructure analysis [60], as well as new physics search studies, like Higgs boson search [61] and heavy quarks search [62,63,64]. The boost decision tree method has been adopted in the light charged Higgs boson search [65]. In Fig.…”

$\mathcal{O}(\alpha_{s})$ corrections to the B-hadron energy distribution of the top decay in the general two Higgs doublet model considering GM-VFN scheme

“…To obtain the total B-hadron energy distribution of the top decay, two contributions due to the decay modes t → bW + (in the SM) and t → bH + (in the 2HDM) should be summed up. However, the contribution of SM is always larger than the one coming from 2HDM [7], but there is a clear separation between the decay channels t → bW + and t → bH + in both the ttX pair production and the t/tX single top production at the LHC [8]. New results of a study on the charged-Higgs bosons in pp collision at a center of mass energy of √ s = 7 TeV are reported by the ATLAS Collaboration [9].…”