# Bounding the Charm Yukawa

## TL;DR

This paper investigates the Higgs coupling to charm quarks, analyzing correlations that allow large deviations in charm coupling without affecting observed Higgs production rates, and updates bounds on this coupling using LHC data.

## Contribution

It provides a comprehensive analysis of the charm Yukawa coupling within the $ppa$ framework, including new indirect bounds and future sensitivity estimates at the LHC.

## Key findings

- Correlations can mask large deviations in charm coupling from SM expectations.
- Updated indirect bounds on the charm Yukawa coupling from LHC measurements.
- Projected future sensitivity of the LHC to the charm coupling at high luminosity.

## Abstract

The study of the properties of the observed Higgs boson is one of the main research activities in High Energy Physics. Although the couplings of the Higgs to the weak gauge bosons and third generation quark and leptons have been studied in detail, little is known about the Higgs couplings to first and second generation fermions. In this article, we study the charm quark Higgs coupling in the so-called $\kappa$ framework. We emphasize the existence of specific correlations between the Higgs couplings that can render the measured LHC Higgs production rates close to the SM values in the presence of large deviations of the charm coupling from its SM value, $\kappa_c = 1$. Based on this knowledge, we update the indirect bounds on $\kappa_c$ through a fit to the precision Higgs measurements at the LHC. We also examine the limits on $\kappa_c$ arising from the radiative decay $H \to J/\psi + \gamma$, the charm quark-associated Higgs production, charm quark decays of the Higgs field and charge asymmetry in $W^{\pm} + H$ production. Estimates for the future LHC sensitivity on $\kappa_c$ at the high luminosity run are provided.