Technipion Limits from LHC Higgs Searches

TL;DR

LHC Higgs searches in di-photon and di-tau channels strongly constrain light technipions predicted by technicolor models, excluding masses from 110 GeV to nearly twice the top-quark mass in certain scenarios.

Contribution

This paper demonstrates how existing LHC Higgs search results can be used to set limits on technipion masses in technicolor models with colored technifermions.

Findings

Technipions have enhanced production and decay rates compared to the SM Higgs.

Current LHC data exclude technipions with masses from 110 GeV to nearly twice the top-quark mass.

Limits depend on model specifics like technicolor group size and extended technicolor effects.

Abstract

LHC searches for the standard model Higgs Boson in di-photon or di-tau decay modes place strong constraints on the light top-pion state predicted in technicolor models that include colored technifermions. Compared with the standard Higgs Boson, the top-pions have an enhanced production rate (largely because the technipion decay constant is smaller than the weak scale) and also enhanced branching ratios into di-photon and di-tau final states (largely due to the suppression of WW decays of the technipions). These factors combine to make the technipions more visible in both channels than a standard model Higgs would be. Hence, the recent ATLAS and CMS searches for Higgs bosons exclude the presence of technipions with masses from 110 GeV to nearly twice the top-quark mass in technicolor models that (a) include colored technifermions (b) feature topcolor dynamics and (c) have technicolor groups with three or more technicolors. For certain models, the limits also apply out to higher technipion masses or down to the minimum number of technicolors. The limits may be softened somewhat in models where extended technicolor plays a significant role in producing the top quark's mass. Additional LHC data on di-tau and di-photon final states will be extremely valuable in further exploring technicolor parameter space.