Probing the Higgs self-coupling with an XFEL Compton γγ collider at $$ \sqrt{s} $$ = 380 GeV

A bstract We present a study probing the Higgs self-coupling with the X-ray free-electron laser Compton γγ Collider (XCC) concept. The analysis is performed considering the γγ → HH → $$ bb\\overline{bb} $$ bb bb ¯ channel and results are then extrapolated to obtain a projection on the Higgs self-coupling sensitivity that ranges between 7% and 12%. An ensemble of boosted decision trees is trained to discriminate between signal and backgrounds, paired with a genetic algorithm optimizer to combine the final classifier outputs. This study suggests that an X-ray FEL-based γγ collider is a powerful tool to probe the mechanism of electroweak symmetry breaking complementary to e + e − Higgs factories and future high energy hadron colliders.