Hot Topics in BABAR

A search for a two-body transition Υ (3S) → γA0, where A0 is a light scalar particle, followed by its decay into 2 muons has been performed using a data sample of (121 ± 1.2) × 106 Υ (3S) decays. As ΓΥ (4S)/ΓΥ (3S) ≈ 10 3, one has greater sensitivity to rare decays using Υ (3S) decays than Υ (4S) samples. The Standard Model (SM) predicts the existence of the Higgs boson to account for the different masses of elementary particles. A single SM Higgs boson is required to be heavy (mH > 114.4 GeV and mH = 170 GeV) 1. This model suffers from the quadratic divergences in the radiative corrections to the mass parameter of the Higgs potential. Other models such as the Minimal Supersymmetric Standard Model (MSSM) regulate this problem but some issues of parameter fine-tuning are not solved. A solution for the MSSM issues is to add additional Higgs fields, where one of them is naturally light. This is the case of Next-to-Minimal Supersymmetric Standard Model (NMSSM). Direct searches constrain mA0 to be below 2mb, therefore accessible to Υ decays. An ideal channel1 is Υ → γA0, which can have a branching fraction up to 10−4 . There are already some results from CLEO1 which impose an upper limit for Υ (1S) → γA0(μ+μ−) ≈