Dilaton at the LHC

TL;DR

This paper investigates the properties and LHC search constraints of the dilaton, a pseudo-Goldstone boson from scale symmetry breaking, highlighting its couplings, experimental limits, and distinguishing features from the Higgs boson.

Contribution

It provides a detailed analysis of dilaton couplings, experimental bounds from LHC data, and methods to differentiate the dilaton from the Higgs boson based on decay channels.

Findings

Dilaton couplings to gluons and photons are enhanced compared to the Higgs.

A dilaton scale f less than 1 TeV is nearly excluded by current LHC data.

Distinct decay signatures can help distinguish the dilaton from the Higgs boson.

Abstract

The dilaton, a pseudo-Nambu-Goldstone boson appearing in spontaneous scale symmetry breaking at a TeV scale f, may be found in Higgs boson searches. The dilaton couples to standard model fermions and weak bosons with the same structure as the Higgs boson except for the overall strength. Additionally, the dilaton couples to a Higgs boson pair. The couplings of the dilaton to a gluon pair and a photon pair, appearing at loop level, are largely enhanced compared to the corresponding Higgs couplings. We present regions of the mass and VEV of the dilaton allowed by WW, ZZ, and gammagamma limits from the LHC at 7 TeV with 1.0-2.3 fb-1 integrated luminosity. A scale of f less than 1 TeV is nearly excluded. We discuss how the dilaton chi can be distinguished from the Higgs boson h by observation of the decays chi -> gammagamma and chi -> hh -> (WW)(WW).