Hunting eta_b through radiative decay into J/psi

Abstract

We propose that the radiative decay process, \eta_b\to J/\psi\gamma, may serve as a clean searching mode for \eta_b in hadron collision facilities. By a perturbative QCD calculation, we estimate the corresponding branching ratio to be of order 10^{-7}. Though very suppressed, this radiative decay channel in fact has larger branching ratio than the hadronic decay process \eta_b\to J/\psi J/\psi, which was previously hoped to be a viable mode for ferreting out \eta_b in Tevatron Run 2. The discovery potential of \eta_b through this channel seems promising in the forthcoming LHC experiments and maybe even in Tevatron Run 2, thanks to the huge statistics of \eta_b to be accumulated in these experiments. The same calculational scheme is also used to estimate the branching ratios for the processes \eta_b (\eta_c) \to \phi\gamma.

Comments: 19 pages, 2 figures. References added/updated. Typo in Fig.1 fixed. Presentation refined. Connection with NRQCD, the major QCD bacground and the impact of NLO correction on the branching ratio are discussed