Search for $H\rightarrow c\bar{c}$ and measurement of $H\rightarrow b\bar{b}$ via $t\bar{t}H$ production

TL;DR

This paper reports a search for Higgs production with top quarks, focusing on the decay to charm quarks, and measures the decay to bottom quarks, setting limits on the charm Yukawa coupling using CMS data.

Contribution

It presents the first combined analysis of $t\bar{t}H$ with Higgs decaying to charm and bottom quarks, providing new constraints on the charm Yukawa coupling.

Findings

Measured $t\bar{t}H(H\rightarrow b\bar{b})$ cross section consistent with SM

Set upper limit of 3.0 times SM on charm Yukawa coupling

Data compatible with SM predictions at 95% confidence level

Abstract

A search is presented for Higgs boson production in association with a top quark-antiquark pair ($t\bar{t}H$) with the Higgs boson decaying to a charm quark-antiquark pair ($H\rightarrow c\bar{c}$). The same process with a Higgs boson decay to bottom quarks, $t\bar{t}H(H\rightarrow b\bar{b})$, is measured simultaneously. The analysis uses data from proton-proton collisions at 13 TeV collected with the CMS detector in 2016-2018, corresponding to an integrated luminosity of 136 fb$^{-1}$. The observed $t\bar{t}H(H\rightarrow\rightarrow b\bar{b}$ cross section relative to its prediction from the standard model (SM) is $0.91\,^{+0.26}_{-0.22}$. The observed (expected) results are compatible at the 95% confidence level with a $t\bar{t}H(H\rightarrow c\bar{c})$ cross section that is at most 7.8 (8.7) times larger than the SM expectation. Assuming all other Higgs boson couplings to be SM-like, this sets an observed (expected) upper bound on the charm quark Yukawa coupling modifier of 3.0 (3.3) times its SM value.