Detecting Traces of Light-Quark Yukawa Couplings to the Higgs Boson in Fragmentation Products

TL;DR

This paper proposes a novel method to detect light-quark Yukawa couplings to the Higgs boson through azimuthal modulations in fragmentation products, offering a new avenue for Higgs sector exploration at the HL-LHC.

Contribution

Introduction of Yukawa Fragmentation Asymmetries (YFAs) as interference observables to probe light-quark Yukawa couplings via hadron fragmentation patterns.

Findings

YFAs are linearly proportional to Yukawa couplings.

YFAs can be measured in $VH$ production at the HL-LHC.

Results outperform current sensitivity projections for first-generation couplings.

Abstract

We point out that Yukawa interactions of light quarks with the Higgs boson are imprinted as unique azimuthal modulations in the density of fragmentation hadrons relative to the Higgs $p_T$. We introduce Yukawa Fragmentation Asymmetries (YFAs), interference observables that are linearly proportional to real (Standard Model) or CP-odd Yukawa couplings, respectively. The chiral suppression is lifted nonperturbatively by chiral-odd multi-hadron fragmentation functions. As a case study, we consider $VH$ production with a tagged target fragmentation hadron at the HL-LHC. We estimate that the YFAs from this single example process are already competitive with current projected HL-LHC sensitivities for second-generation couplings, and outperform them by a factor of 2-3 for first-generation couplings. Our results point to deep synergies between precision studies of confinement and the in-depth exploration of the Higgs sector.