Beyond Higgs couplings: probing the Higgs with angular observables at future e+e- colliders

We study angular observables in the e(+)e(-) -> ZH -> l(+)l(-) b (b) over bar 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 root 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 HZ gamma coupling and constraining the blind spot in indirect limits on supersymmetric scalar top partners.