Signatures of anomalous Higgs couplings in angular asymmetries of H --> Zl+l- and e+e- --> HZ

TL;DR

This paper investigates how anomalous Higgs couplings, parametrized by dimension-six operators, influence angular asymmetries in Higgs decay and production processes, revealing potential BSM effects detectable through these asymmetries.

Contribution

It demonstrates that angular asymmetries can uncover beyond Standard Model Higgs couplings that are hidden in other observables, especially in the context of current bounds on dimension-six operators.

Findings

Asymmetries can reveal BSM effects at the several percent level.

Higher di-lepton invariant mass in e+e- collisions offers complementary search avenues.

Certain couplings induce asymmetries with less impact on invariant mass spectra.

Abstract

Parametrizing beyond Standard Model physics by the SU(3) x SU(2)_L x U(1)_Y dimension-six effective Lagrangian, we study the impact of anomalous Higgs couplings in angular asymmetries of the crossing-symmetric processes H --> Zl+l- and e+e- --> HZ. In the light of present bounds on d=6 couplings, we show that some asymmetries can reveal BSM effects that would otherwise be hidden in other observables. The d=6 HZgamma couplings as well as (to a lesser extent) HZll contact interactions can generate asymmetries at the several percent level, albeit having less significant effects on the di-lepton invariant mass spectrum of the decay H --> Zl+l-. The higher di-lepton invariant mass probed in e+e- --> HZ can lead to complementary anomalous coupling searches at e+e- colliders.