Constraints on the Higgs boson width from off-shell production and decay to Z-boson pairs

TL;DR

This paper constrains the total width of the Higgs boson by analyzing its off-shell and on-shell production rates to Z boson pairs using CMS data, setting an upper limit of 22 MeV at 95% CL.

Contribution

It introduces a method to constrain the Higgs boson width using off-shell production data, providing the first such limit based on LHC measurements.

Findings

Higgs boson width < 22 MeV at 95% CL

Method combines on-shell and off-shell production rates

Results are 5.4 times the Standard Model expectation

Abstract

Constraints are presented on the total width of the recently discovered Higgs boson, Gamma[H], using its relative on-shell and off-shell production and decay rates to a pair of Z bosons, where one Z boson decays to an electron or muon pair, and the other to an electron, muon, or neutrino pair. The analysis is based on the data collected by the CMS experiment at the LHC in 2011 and 2012, corresponding to integrated luminosities of 5.1 inverse femtobarns at a centre-of-mass energy sqrt(s) = 7 TeV and 19.7 inverse femtobarns at sqrt(s) = 8 TeV. A simultaneous maximum likelihood fit to the measured kinematic distributions near the resonance peak and above the Z-boson pair production threshold leads to an upper limit on the Higgs boson width of Gamma[H] < 22 MeV at a 95% confidence level, which is 5.4 times the expected value in the standard model at the measured mass.