Eur. Phys. J. C (2008) 54: 129-147
https://doi.org/10.1140/epjc/s10052-007-0503-4

Regular Article - Theoretical Physics

Exploring the di-photon decay of a light Higgs boson in the MSSM with explicit CP violation

¹ School of Physics and Astronomy, University of Southampton, Highfield, Southampton, SO17 1BJ, UK
² Laboratoire de Physique Théorique, Université Paris-Sud, 91405, Orsay Cedex, France
³ Physics Department, IIT Guwahati, Assam, 781039, India

^* e-mail: poulose@iitg.ernet.in

Received: 31 August 2007
Revised: 30 November 2007
Published online: 26 January 2008

Abstract

The di-photon decay channel of the lightest Higgs boson is considered as a probe to explore CP violation in the minimal supersymmetric standard model (MSSM). The scalar/pseudo-scalar mixing is considered along with CP violation entering through the Higgs–sfermion–sfermion couplings, with and without light sparticles. The impact of a light stop on the decay width and branching ratio (BR) is established through a detailed study of the amplitude of the process H₁→γγ. The other sparticles have little influence even when they are light. With a suitable combination of other MSSM parameters, a light stop can change the BR by more than 50% with a CP-violating phase φ_μ∼90°, while the change is almost nil with a heavy stop.