Search for Radiative Decays of Upsilon(1S) Into Eta and Eta-prime PDF Download

Author: Vijay Singh Potlia
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Languages : en
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ABSTRACT: We conducted a new search for the radiative decay of Upsilon(1S) to the pseudoscalar mesons eta and eta-prime in (21.2"0.2) x 106 Upsilon(1S) decays collected with the CLEO III detector operation at the Cornell Electron Strorage Ring (CESR). The eta meson was reconstructed in the three modes eta to gamma gamma, eta to pipi−pi0 or eta to pi0 pi0 pi0. The eta-prime meson was reconstructed in the mode eta-prime to pi pi− eta with eta decaying through any of the above three modes; and also eta-prime to gamma rho0, where rho0 to pi+ pi−-. The first six of these decay chains were searched for in the previous CLEO II analysis on this subject, which used a data sample 14.6 times smaller. Five of the seven submodes were virtually background free. We found no signal events in four of them. The only exception was Upsilon(1S) to gamma eta-prime; eta to pi+ pi− pi0 where we observed two good signal candidates. The other two submodes (eta to gamma gamma and eta-prime to gamma rho) are background limited, and showed no excess of events in the signal region. We combined the results from different channels and obtained 90% confidence level (C.L.) upper limits branching fraction(Upsilon(1S) to gamma eta)