Résumé
JHEP 0901:061,2009 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.