%0 Journal Article %T Radiative Upsilon decays and a light pseudoscalar Higgs in the NMSSM %A Domingo %A Florian %A Ellwanger %A Ulrich %A Fullana %A Esteban %A Hugonie %A Cyril %A Sanchis-Lozano %A Miguel-Angel %J High Energy Physics - Phenomenology %D 2008 %I %R 10.1088/1126-6708/2009/01/061 %X We study possible effects of a light CP-odd Higgs boson on radiative Upsilon decays in the Next-to-Minimal Supersymmetric Standard Model. Recent constraints from CLEO on radiative Upsilon(1S) decays are translated into constraints on the parameter space of CP-odd Higgs boson masses and couplings, and compared to constraints from B physics and the muon anomalous magnetic moment. Possible Higgs - eta_b(nS) mixing effects are discussed, notably in the light of the recent measurement of the eta_b(1S) mass by Babar: The somewhat large Upsilon(1S) - eta_b(1S) hyperfine splitting could easily be explained by the presence of a CP-odd Higgs boson with a mass in the range 9.4 - 10.5 GeV. Then, tests of lepton universality in inclusive radiative Upsilon decays can provide a visible signal in forthcoming experimental data. %U http://arxiv.org/abs/0810.4736