First Glimpses at Higgs' face

TL;DR

This paper analyzes early LHC Higgs data to assess how closely the observed scalar matches the Standard Model Higgs and explores implications for new physics through joint coupling fits and model-independent methods.

Contribution

It provides a comprehensive joint fit of Higgs couplings to current data, evaluating deviations from the Standard Model and developing techniques to constrain alternative models.

Findings

Higgs couplings are within ~2 sigma of SM predictions

Invisible decay branching ratio is constrained to BR_{inv} = 0.05 ± 0.32

Methods to exclude models with significantly altered Higgs properties are proposed

Abstract

The 8 TeV LHC Higgs search data just released indicates the existence of a scalar resonance with mass ~ 125 GeV. We examine the implications of the data reported by ATLAS, CMS and the Tevatron collaborations on understanding the properties of this scalar by performing joint fits on its couplings to other Standard Model particles. We discuss and characterize to what degree this resonance has the properties of the Standard Model (SM) Higgs, and consider what implications can be extracted for New Physics in a (mostly) model-independent fashion. We find that, if the Higgs couplings to fermions and weak vector bosons are allowed to differ from their standard values, the SM is ~ 2 sigma from the best fit point to current data. Fitting to a possible invisible decay branching ratio, we find BR_{inv} = 0.05\pm 0.32\ (95% C.L.) We also discuss and develop some ways of using the data in order to bound or rule out models which modify significantly the properties of this scalar resonance and apply these techniques to the global current data set.