Search for very light CP-odd Higgs boson in radiative decays of Υ(1S)

We search for a non-SM-like CP-odd Higgs boson (a{sub 1}{sup 0}) decaying to {tau}{sup +}{tau}{sup -} or {mu}{sup +}{mu}{sup -} in radiative decays of the {upsilon}(1S). No significant signal is found, and upper limits on the product branching ratios are set. Our {tau}{sup +}{tau}{sup -} results are almost 2 orders of magnitude more stringent than previous upper limits. Our data provide no evidence for a Higgs state with a mass of 214 MeV decaying to {mu}{sup +}{mu}{sup -}, previously proposed as an explanation for 3 {sigma}{sup +}{yields}p{mu}{sup +}{mu}{sup -} events observed by the HyperCP experiment. Our results constrain NMSSM models.