One-loop pseudoscalar mass in a 2HDM with a Z 3 symmetry

Abstract

Abstract A two-Higgs doublet model with a discrete Z 3 symmetry acquires, in its scalar and gauge sectors, an accidental continuous U(1) symmetry. One therefore finds, after spontaneous symmetry breaking of those symmetries, that a massless pseudoscalar arises, as expected by Goldstone’s theorem. In the fermion sector, however, it is possible to obtain Yukawa matrix textures which distinguish between the Z 3 and U(1) symmetries, so one expects loop corrections to originate a non-zero pseudoscalar mass for the Z 3 case. We perform an explicit calculation that shows that at one-loop the pseudoscalar remains massless for all but one tested Z 3 Yukawa matrices. The pseudoscalar mass thus found is highly suppressed by the hierarchy of fermion masses.

Keywords

• Multi-Higgs Models
• Discrete Symmetries
• Global Symmetries