Search for Higgs Bosons and New Particles Decaying into Two Photons at sqrt(s) = 183 GeV

TL;DR

This study searched for Higgs bosons and new particles decaying into two photons at 183 GeV, setting limits on their production and decay rates, but found no evidence of non-Standard Model physics within the analyzed data.

Contribution

First search for Higgs and new scalar particles decaying into photon pairs at this energy, establishing new upper limits on production cross sections and branching ratios.

Findings

No evidence for non-Standard Model processes was observed.

Limits on Higgs boson decays to gamma gamma are set up to 92 GeV.

Higgs scalars coupling only to gauge bosons are excluded up to 90 GeV.

Abstract

A search for the resonant production of high mass photon pairs associated with a leptonic or hadronic system has been performed using a data sample of 57.7 pb-1 collected at an average center-of-mass energy of 182.6 GeV with the OPAL detector at LEP. No evidence for contributions from non-Standard Model physics processes was observed. The observed candidates are used to place limits on BR (H to gamma gamma) assuming a Standard Model production rate for Higgs boson masses up to 92 GeV, and on the production cross section for a scalar resonance decaying into di-photons up to a mass of 170 GeV. Upper limits on the product of cross section and branching ratios, sigma(e+e- to XY) * BR(X to gamma gamma) * BR(Y to f fbar) as low as 70fb are obtained over the M(X) range 10 - 170 GeV for the case where 10 < M(Y) < 160 GeV and M(X)+M(Y) > 90 GeV, independent of the nature of Y provided it decays to a fermion pair and has negligible width. Higgs scalars which couple only to gauge bosons at Standard Model strength are ruled out up to a mass of 90.0 GeV at the 95% confidence level. Limits are also placed on non-minimal Higgs sectors having triplet representations.