# Pseudoscalar pair production via off-shell Higgs in composite Higgs models

### Submission summary

 As Contributors: Diogo Buarque Franzosi · Gabriele Ferretti Arxiv Link: https://arxiv.org/abs/2005.13578v1 (pdf) Date submitted: 2020-06-03 Submitted by: Buarque Franzosi, Diogo Submitted to: SciPost Physics Discipline: Physics Subject area: High-Energy Physics - Phenomenology Approaches: Theoretical, Experimental, Phenomenological

### Abstract

We propose a new type of search for a pseudoscalar particle $\eta$ pair produced via an off-shell Higgs, $pp\to h^*\to \eta\eta$. The search is motivated by a composite Higgs model in which the $\eta$ is extremely narrow and decays almost exclusively into $Z\gamma$ in the mass range $65$ GeV$\lesssim m_\eta \lesssim 160$ GeV. We devise an analysis strategy to observe the novel $Z\gamma Z\gamma$ channel and estimate potential bounds on the Higgs-$\eta$ coupling. The experimental sensitivity to the signatures depends on the power to identify fake photons and on the ability to predict large photon multiplicities. This search allows us to exclude large values of the compositeness scale $f$, being thus complementary to other typical processes.

###### Current status:
Editor-in-charge assigned

### Submission & Refereeing History

Submission 2005.13578v1 on 3 June 2020

## Reports on this Submission

### Strengths

1) Complete phenomenological study, from detailed model-building to collider
2) Impeccable LHC simulation and search proposal
3) Well motivated and novel

### Weaknesses

1) Proposed signature, while possible, is non generic

### Report

This wel-written article provides a thorough of composite-Higgs models in which the Higg sector contains an additional scalar singlet field (as Pseudo Goldstone boson). The authors show that in certain regions of parameter space (possible and protected by a symmetry) the extra singlet decays predominantly to Zgamma, and a favorable search channel is h_>eta eta->ZgammaZgamma. The article provides a detailed study of the discovery perspective at LHC (for 300 and 3000 1/fb).

### Requested changes

1) In the intro (p2) it is said that the singlet "couplings to fermions are also typically small". It seems to me that they rather "can be small" in certain regions of parameter space protected by a symmetry (i.e. a generic embedding in the 6 representation would have sizeable fermion couplings)
2) In the statistical analysis (p11) the authors provide formula 3.3. This appears to me slightly out of context: I'd rather provide more details about how this formiula is used, or omit it.
3) In the conclusions (p19) it is said that "...allows us to exclude large values of f". This is not completely obvious from fig 12 (for which the bulk of the exclusion is at small f); so perhaps the authors could specify that they refer to the small m_eta region, if this is what is meant.

• validity: top
• significance: high
• originality: high
• clarity: top
• formatting: perfect
• grammar: perfect