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

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 simple example process, we consider $VH$ production with a tagged target fragmentation hadron at the HL-LHC. We find promising projected sensitivities to first and second-generation couplings while maintaining superior control over theory systematics, flavor separation, and model independence compared to present methods. Our results point to deep synergies between precision studies of confinement and the in-depth exploration of the Higgs sector.