Associated production of Higgs and single top at hadron colliders

TL;DR

This paper analyzes Higgs production in association with a single top quark at hadron colliders, detailing three production channels (t-channel, s-channel, W-associated) and computing their leading-order cross sections. It explains why the th rate is suppressed—primarily due to destructive interference among contributing diagrams—and examines the feasibility of observing h→bb signals at the LHC, finding backgrounds challenging to overcome. The study extends to MSSM Higgs bosons, showing modest enhancements at large tanβ but emphasizing that unitarity cancellations and competing couplings limit the gains. Overall, the work clarifies interference effects in th production and provides guidance on the experimental prospects for Higgs+single-top searches in both the SM and MSSM contexts.

Abstract

We study the production of the Higgs boson in association with a single top quark at hadron colliders. The cross sections for the three production processes (t-channel, s-channel, and W-associated) at both the Tevatron and the LHC are presented. We investigate the possibility of detecting a signal for the largest of these processes, the t-channel process at the LHC, via the Higgs decay into b b-bar. The QCD backgrounds are large and difficult to curb, hindering the extraction of the signal. Extensions of our analysis to the production of supersymmetric Higgs bosons are also addressed. The cross section is enhanced for large values of tangent beta, increasing the prospects for extracting a signal.

Figures (14)

• Figure 1: Feynman diagrams contributing to the $t$-channel production of Higgs plus single top.
• Figure 2: Feynman diagrams contributing to the $s$-channel production of Higgs plus single top.
• Figure 3: Feynman diagrams contributing to the $W$-associated production of Higgs plus single top.
• Figure 4: Cross sections for production of Higgs plus single top at the Tevatron ($p\bar{p}$, $\sqrt{s}=2$ TeV) and at the LHC ($pp$, $\sqrt{s}=14$ TeV). Cross sections for the $t$-channel, $s$-channel and $W$-associated processes are shown. For comparison the cross section for $t\bar{t}h$ is also shown. The set of parton distribution functions is CTEQ5L, and the renormalization and factorization scales are set equal to the Higgs mass.
• Figure 5: Interference in the $t$-channel process at the Tevatron and at the LHC. The contributions from the $t$-Higgs coupling only and the $W$-Higgs coupling only, normalized to the total cross section at any given Higgs mass, are shown.