Photon Emission

Heavy quark physics is one of the frontier areas in studies of the fundamental properties of matter. That is why a new generation of ee colliders (B-factories) has been designed. The CLEO-III , BELLE , and BABAR 3 experiments are running since 1999. Their main goal is the precise investigation of the CabibboKobayashi-Maskawa matrix and, first of all, CP-violation in the b-quark sector. To achieve this goal, most of the time will be spent on running at the energy of the Υ(4S) resonance. At the same time there are physical tasks 4 related with the spectroscopy of quarkonium systems which require scanning the energy region of Υ(1S), Υ(2S), Υ(3S). Such experiments were performed at DORIS, CESR, and VEPP-4 . The main part of the bottomonium family has been observed, their masses and main decay modes have been measured. The list of experiments with the largest integrated luminosity is shown in Table 1. However, the accuracy of the measured parameters of the bottomonium family is not very high, preventing from the precise comparison between the data and different model predictions for the mass spectrum, decay rates, and dynamics of transitions. Moreover, some predicted states (ηb(2S), ηb(1S), hb(1P )) have not yet been observed or are not well established. Thus, new experiments are necessary which will provide complete information about all states below the open flavor threshold. Unfortunately, scans of the Υ(1S), Υ(2S), Υ(3S) are not foreseen at asymmetric B-factory experiments. Of course, it can be done in a traditional way by CLEOIII but that will decrease the total integrated luminosity which is expected to be collected by CLEO-III at Υ(4S). That is why we consider a possibility to perform Υ-spectroscopy studies at the Υ(4S) energy using the emission of a hard photon by the electron or the positron. This process is well known, it changes the value of the