Decay of a light pseudo-scalar Higgs boson to the Υ-meson and a photon

Abstract: This paper is concerned with calculating the branching ratio of the decay A1 −→ Υ + γ of a pseudo-scalar Higgs boson, where Υ is a bound vector meson state of the quarks b and b-bar The results will then be applied to the b. phenomenology of the Next-to-Minimal Supersymmetric Standard Model in the case where A1 has a mass in the interval 9.46 − 12 GeV . The paper will review the concept of spontaneous symmetry breaking through a few simple examples and present the Higgs mechanism of the Standard Model. Following this is a general introduction to supersymmetric extensions of the Standard Model and a discussion of the Minimal Supersymmetric Standard Model and Next-to-Minimal Supersymmetric Standard Model. After a development of the formalism for treating decays to bound states the branching ratio for the decay A1 −→ Υ + γ is computed at tree-level in the limit where the relative velocities of the b-quarks in Υ are non-relativistic. For Higgs particle masses in the interval 9.66 − 10.5 GeV it is shown that the branching ratio BR(A1 → Υ + γ) is large enough so that the decay channel could give an opportunity to detect the pseudo-scalar Higgs boson in that mass range.