Probing light Yukawa couplings in Higgs pair production

Abstract: One of the puzzles of the SM is the large hierarchy between the Yukawa couplings of different flavours. Yukawa couplings of the first and the second generation are constrained only very weakly so far. However, one can obtain large deviations in the Yukawa couplings in several New Physics (NP) models, such as e.g. models with new vector-like quarks, or new Higgs bosons that couple naturally to individual fermion families. In this work, we investigate the potential bounds on the NP Higgs Yukawa couplings modification $ \kappa_f$ for light quarks from double-Higgs at the LHC, starting from a model independent formalism. We have looked at the two Higgs boson final state $ b \bar b \gamma \gamma $, and the relevant experimental cuts to reduce backgrounds and estimated the potential exclusion bounds for $ \kappa_f$. We have considered both linear and non-linear effective field theory for the Higgs light quark coupling modifications.