Probing for Invisible Higgs Decays with Global Fits

TL;DR

This paper uses a global fit to Higgs data to show that large invisible decay rates are still compatible with current experiments, and proposes tests to improve future detection prospects.

Contribution

It introduces a comprehensive method combining all visible Higgs signals to better constrain invisible decay rates and explores effects of coupling deviations on these conclusions.

Findings

Invisible Higgs branching ratio Br_{inv} < 0.64 at 95% CL

Proposes novel combined tests for future experimental improvements

Analyzes impact of coupling deviations on invisible decay constraints

Abstract

We demonstrate by performing a global fit on Higgs signal strength data that large invisible branching ratios Br_{inv} for a Standard Model (SM) Higgs particle are currently consistent with the experimental hints of a scalar resonance at the mass scale m_h ~ 124 GeV. For this mass scale, we find Br_{inv} < 0.64 (95 % CL) from a global fit to individual channel signal strengths supplied by ATLAS, CMS and the Tevatron collaborations. Novel tests that can be used to improve the prospects of experimentally discovering the existence of a Br_{inv} with future data are proposed. These tests are based on the combination of all visible channel Higgs signal strengths, and allow us to examine the required reduction in experimental and theoretical errors in this data that would allow a more significantly bounded invisible branching ratio to be experimentally supported. We examine in some detail how our conclusions and method are affected when a scalar resonance at this mass scale has couplings deviating from the SM ones.