Using the CLEO II detector at CESR, we measure the eta' - gluon - gluon form-factor in Y(1S) decays. This form-factor especially at large eta' energies may provide an explanation of the large rate for B -> Xs eta'. Our data do not support a large anomalous coupling at higher q^2 and thus the large eta' rate remains a mystery, possibly requiring a non-Standard Model explanation.
Categories: hep-ex