Search for di-muon decays of a light scalar higgs boson in radiative Y(1S) decays

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We search for di-muon decays of a low-mass Higgs boson (A0) in the fully reconstructed decay chain of D(2S, 3S ) D D+DDD(1S ), D(1S ) D DA0, A0 D D+DD. The A0 is predicted by several extensions of the Standard Model (SM), including the Next-to-Minimal Supersymmetric Standard Model (NMSSM). NMSSM introduces a CP-odd light Higgs boson whose mass could be less than 10 GeV/c2. The data samples used in this analysis contain 92.8 D 106 D(2S ) and 116.8 D 106 D(3S ) events collected by the BABAR detector. The D(1S ) sample is selected by tagging the pion pair in the D(2S, 3S ) D D+DDD(1S ) transitions. We find no evidence for A0 production and set 90% confidence level (C.L.) upper limits on the product branching fraction B(D(1S ) D DA0) D B(A0 D D+DD) in the range of (0.28 D 9.7) D 10D6 for 0.212 D mA0 D 9.20 GeV/c2. We also combine our results with previous BABAR results of D(2S, 3S ) D DA0, A0 D D+DD to set limits on the effective coupling ( fD) of the b-quark to the A0, f 2D D B(A0 D D+DD), at the level of (0.29 D 40) D 10D6 for 0.212 D mA0 D 9.2 GeV/c2..
Supervisor: Bipul Bhunya and P. Poulose