First Search for the Associated Production of a Higgs Boson with a Single Top Quark

TL;DR

This paper reports the first search for Higgs boson production with a single top quark across multiple decay channels, using CMS data at 8 TeV, to probe the Yukawa coupling Yt, especially for Yt=-1.

Contribution

It presents the first combined search for single-top plus Higgs production in various decay channels with CMS data, focusing on the Yt=-1 scenario.

Findings

Observed upper limit is 2.8 times the exotic Yt=-1 scenario cross section.

Analysis optimized for Yt=-1 scenario, which is 13 times the Standard Model rate.

Systematic uncertainties and analysis peculiarities are thoroughly discussed.

Abstract

The production of the Higgs boson in association with a single top quark is sensitive to the relative sign of the coupling parameters describing its interaction with fermions and gauge bosons. The tHq production mode therefore provides an good handle on the Yukawa coupling Yt. The first searches for single-top + Higgs in the H>bbbar, gamma gamma, tau+tau- and W+W- decay channels are presented, using the full 8 TeV dataset recorded with the CMS detector. Special emphasis is put on the analyses' peculiarities and their dominating systematic uncertainties, and a combination of all individual channels is performed. The analyses are optimized for a scenario of Yt=-1, which is enhanced by a factor of 13 with respect to the Standard Model production rate. The observed combined upper exclusion limit is 2.8 times the cross section of this exotic scenario (2.0 expected).