Search for a Higgs boson in the mass range from 145 to 1000 GeV decaying to a pair of W or Z bosons (1504.00936v2)

Abstract: A search for a heavy Higgs boson in the H to WW and H to ZZ decay channels is reported. The search is based upon proton-proton collision data samples corresponding to an integrated luminosity of up to 5.1 inverse femtobarns at sqrt(s) = 7 TeV and up to 19.7 inverse femtobarns at sqrt(s) = 8 TeV, recorded by the CMS experiment at the CERN LHC. Several final states of the H to WW and H to ZZ decays are analyzed. The combined upper limit at the 95% confidence level on the product of the cross section and branching fraction exclude a Higgs boson with standard model-like couplings and decays in the range 145 < m[H] < 1000 GeV. We also interpret the results in the context of an electroweak singlet extension of the standard model.

• The paper reports a comprehensive search for a heavy Higgs boson decaying into WW or ZZ using CMS proton-proton collision data.
• It employs advanced techniques like boosted decision trees and jet substructure analysis to optimize signal extraction across multiple decay channels.
• The study finds no significant excess over Standard Model predictions, excluding a SM-like heavy Higgs boson from 145 to 1000 GeV at 95% confidence level.

Search for a Higgs Boson in the Mass Range from 145 to 1000 GeV Decaying to a Pair of W or Z Bosons

This paper documents a comprehensive search for a heavy Higgs boson within the mass range of 145 to 1000 GeV, focusing on its decay into pairs of W or Z bosons. Conducted using data from the CMS experiment at the CERN Large Hadron Collider (LHC), this paper employs proton-proton collision datasets corresponding to integrated luminosities of up to 5.1 fb$^{-1}$ at a center-of-mass energy of $\sqrt{s} = 7$ TeV and up to 19.7 fb$^{-1}$ at $\sqrt{s} = 8$ TeV.

The analysis investigates multiple decay channels: the fully leptonic and semi-leptonic final states of Higgs decays into WW, and the four-lepton, two-lepton-two-quark, and two-lepton-two-neutrino final states for ZZ decays. The results indicate no significant excess over the Standard Model (SM) background expectations, leading to the exclusion of a Higgs boson with SM-like couplings in the range 145 < $m_{H}$ < 1000 GeV at 95% confidence level (CL). This suggests constraints on extended Higgs sectors, such as those positing additional electroweak singlet states.

The searches for high-mass Higgs bosons are motivated by theories like two-Higgs-doublet models and scenarios involving heavy electroweak singlets. The presence of a heavy Higgs boson could answer outstanding questions about electroweak symmetry breaking. Previous searches by CMS and ATLAS have ruled out significant portions of parameter space for these theories, yet some gaps remain, which this paper seeks to address.

Key methodologies involve the use of advanced event-selection techniques, such as boosted decision trees and jet substructure analysis, particularly crucial in the search for high-mass Higgs where W and Z bosons may be highly relativistic. The analysis pipeline incorporates corrections from Monte Carlo simulations, systematic uncertainty evaluations, and optimization of signal extraction methods across numerous jet and lepton configurations.

A significant aspect of this work is the interpretation of results in terms of an electroweak singlet model extension of the Standard Model. This model hypothesizes a mixing between the SM Higgs boson and an additional heavy partner, resulting in an altered resonance spectrum. The paper's findings place substantial limits on the possible contribution of this heavy electroweak singlet to observed phenomena, depending on its production and decay mechanisms.

The paper's results have implications for ongoing and future studies at the LHC, particularly with regard to exploring new regions of parameter space in BSM physics. The exclusionary findings narrow down the characteristics of potential new physics scenarios, guiding both theoretical and experimental efforts as collider experiments continue to probe the TeV scale. Future work could expand to higher energy datasets and enhanced detector capabilities, potentially uncovering more subtle signs of new physics.