Beyond Higgs Couplings: Probing the Higgs with Angular Observables at Future e$^+$ e$^−$ Colliders

摘要: We study angular observables in the e+e−→ZH→ℓ+ℓ−bb¯ channel at future circular e+e− colliders such as CEPC and FCC-ee. Taking into account the impact of realistic cut acceptance and detector effects, we forecast the precision of six angular asymmetries at CEPC (FCC-ee) with center-of-mass energy s√= 240 GeV and 5 (30) ab−1 integrated luminosity. We then determine the projected sensitivity to a range of operators relevant for the Higgs-strahlung process in the dimension-6 Higgs EFT. Our results show that angular observables provide complementary sensitivity to rate measurements when constraining various tensor structures arising from new physics. We further find that angular asymmetries provide a novel means of both probing BSM corrections to the HZγ coupling and constraining the "blind spot" in indirect limits on supersymmetric scalar top partners.