Search for exclusive radiative decays of ϒ(1S) and ϒ(2S) mesons

Using the ARGUS detector at the DORIS II storage ring we have searched for radiative decays Υ(1S)→γX, whereX decays into two oppositely charged pions, kaons, or protons. Upper limits on branching fractions are presented. In the π+π- invariant mass region 290–570 MeV/c2 the upper limit obtained varies from 3 to 4.5×10−5. These values are lower than the theoretical prediction of about 5×10−5 for Higgs production, which includes perturbative QCD radiative corrections to the Wilczek formula and the estimate Br(H0→π+π-), accounting for Higgs coupling to gluons via heavy quark loops. Previous experimental results do not exclude the existence of a standard minimal Higgs in this mass region.