Speaker
Description
While the third-generation couplings of the Higgs boson have been observed and studied, the first and second-generation fermion couplings to the Higgs (except the Higgs-muon coupling) remain elusive. This is due to two reasons mostly: light quark Yukawas smallness, and the difficulty of tagging light quarks efficiently. Therefore, even at the High Luminosity LHC (HL- LHC), the projections for the light quark Yukawa couplings, especially for the first generations, remain orders of magnitude away from the Standard Model prediction.
In this work, we try to address the question of how large the light quark Yukawa couplings can be by considering concrete UV scenarios using simplified models. Particularly, we explore various models with vector-like quarks that generate EFT operators that modify the couplings of the light quarks to the Higgs boson. We examine the impact of constraints from electroweak precision observables, Higgs data, and flavor physics, and find that it is still possible to achieve significant deviations in the Yukawa couplings of the light generations, around O(1000) for the first generation and around O(50) for the second generation, even with vectorlike quarks with masses in the few TeV range. These maximized contributions to the light Yukawa couplings are achieved by allowing only one generation to couple to the new states, thereby suppressing the flavor constraints. Effectively, our analysis sets such models as a clear experimental target at the HL-LHC and partially motivates the continuation of light-quark Yukawa measurements at future facilities, as this is often the best way to access the vectorlike fermion states coupled to only one light generation.
| Primary track | BSM Higgs physics |
|---|---|
| Is the speaker a PhD student or post-doc? | Yes - I need some financial support (fee reduction) to attend Higgs 2024 |
