Enhancement of H to gamma gamma from doubly charged scalars in the Higgs Triplet Model

Enhancement of H to gamma gamma from doubly charged scalars in the Higgs Triplet Model

The Higgs boson of the Standard Model is being searched for at the LHC in the channel H -> gamma gamma. In the Higgs Triplet Model (HTM) there are contributions to this decay from loops of doubly charged scalars (H^{\pm\pm}) and singly charged scalars (H^\pm) that are not present in the Standard Model. These additional contributions are mediated by the trilinear couplings H_1 H^{++}H^{--} and H_1 H^{+}H^{-}, where H_1 is the lightest CP-even Higgs boson. We point out the possibility of constructive interference of the H^{\pm\pm} contribution with that of the W^\pm contribution, which enables a substantial enhancement of the branching ratio of H_1 -> gamma gamma in the HTM. The magnitude of the contribution of $H^{\pm\pm}$ is essentially determined by the mass of H^{\pm\pm} (m_{H^{\pm\pm}}) and a quartic scalar coupling (\lambda_1), with constructive interference arising for \lambda_1 gamma gamma restrict the parameter space of [m_{H^{\pm\pm}},\lambda_1] more stringently for \lambda_1 0. Moreover, if the excess of gamma gamma events around a mass of 125 GeV in the LHC searches for H -> gamma gamma is substantiated with larger data samples, and the branching ratio is measured to be somewhat larger than that for the SM Higgs boson, then such an enhancement could be readily accommodated by H_1 in the HTM with \lambda_1

035015-[11pp]

Akeroyd, A. G.

e5de827d-7119-41c2-9f1e-5ef123afdf98

Moretti, S.

b57cf0f0-4bc3-4e02-96e3-071255366614

1 August 2012

Akeroyd, A. G.

e5de827d-7119-41c2-9f1e-5ef123afdf98

Moretti, S.

b57cf0f0-4bc3-4e02-96e3-071255366614

Akeroyd, A. G. and Moretti, S.
(2012)
Enhancement of H to gamma gamma from doubly charged scalars in the Higgs Triplet Model.
*Physical Review D*, 86 (3), .
(doi:10.1103/PhysRevD.86.035015).

## Abstract

The Higgs boson of the Standard Model is being searched for at the LHC in the channel H -> gamma gamma. In the Higgs Triplet Model (HTM) there are contributions to this decay from loops of doubly charged scalars (H^{\pm\pm}) and singly charged scalars (H^\pm) that are not present in the Standard Model. These additional contributions are mediated by the trilinear couplings H_1 H^{++}H^{--} and H_1 H^{+}H^{-}, where H_1 is the lightest CP-even Higgs boson. We point out the possibility of constructive interference of the H^{\pm\pm} contribution with that of the W^\pm contribution, which enables a substantial enhancement of the branching ratio of H_1 -> gamma gamma in the HTM. The magnitude of the contribution of $H^{\pm\pm}$ is essentially determined by the mass of H^{\pm\pm} (m_{H^{\pm\pm}}) and a quartic scalar coupling (\lambda_1), with constructive interference arising for \lambda_1 gamma gamma restrict the parameter space of [m_{H^{\pm\pm}},\lambda_1] more stringently for \lambda_1 0. Moreover, if the excess of gamma gamma events around a mass of 125 GeV in the LHC searches for H -> gamma gamma is substantiated with larger data samples, and the branching ratio is measured to be somewhat larger than that for the SM Higgs boson, then such an enhancement could be readily accommodated by H_1 in the HTM with \lambda_1

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## More information

Published date: 1 August 2012

Additional Information:
16 pages, 4 figures

Organisations:
Theory Group

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Local EPrints ID: 356684

URI: https://eprints.soton.ac.uk/id/eprint/356684

ISSN: 1550-7998

PURE UUID: 2a95f579-3a0d-4c6e-a118-7a14f514fbaf

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Date deposited: 16 Sep 2013 10:26

Last modified: 18 Jul 2017 03:37

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## Contributors

Author:
A. G. Akeroyd

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