Two-nucleon {{\phi}} -Meson Clusters

The binding energies of the systems ${{\phi n n}}$ , ${{\phi n p}}$ , and ${{\phi p p}}$ are calculated on the basis of Faddeev equations. The results indicate the possibility of new few-nucleon meson clusters.     

Rescattering effects in \phi photoproduction

We calculate the contribution from rescattering of pairs produced by photoproduction of to the photoproduction of mesons. The photoproduction of mesons is presently a hot topic due to the possibility that an intrinsic hidden strangeness contribution in the nucleon flavor wave function may be revealed in this process, and due to the possibility that the structure of scalar mesons could be accessible experimentally via interference in the system. We show that rescattering makes an important contribution to photoproduction which could – if neglected – mislead the interpretation of the forthcoming high precision data. Received: 14 September 2000 / Revised version: 1 February 2001 / Published online: 12 April 2001     

Search for invisible decays of eta and eta' in J/psi --> phi eta and phi eta'

Using a data sample of 58 x 10(6) J/psi decays collected with the Beijing Spectrometer II detector at the Beijing Electron Positron Collider, searches for invisible decays of eta and eta' in J/psi to phi eta and phi eta' are performed. The phi signals, which are reconstructed in K+K- final states, are used to tag the eta and eta' decays. No signals are found for the invisible decays of either eta or eta', and upper limits at the 90% confidence level are determined to be 1.65 x 10(-3) for the ratio B(eta-->invisible)/B(eta --> gamma gamma) and 6.69 x 10(-2) for B(eta' --> invisible)/B(eta' --> gammagamma). These are the first searches for eta and eta' decays into invisible final states.     

Near-threshold production of phi mesons in pp collisions

The pp-->ppphi reaction has been studied at the Cooler Synchrotron COSY-Jülich, using the internal beam and ANKE facility. Total cross sections have been determined at three excess energies epsilon near the production threshold. The differential cross section closest to threshold at epsilon=18.5 MeV exhibits a clear S wave dominance as well as a noticeable effect due to the proton-proton final-state interaction. Taken together with data for ppomega production, a significant enhancement of the phi/omega ratio of a factor 8 is found compared to predictions based on the Okubo-Zweig-Iizuka rule.     

Observation of radiative B-->phi K gamma decays

The radiative decay B-->phi K gamma is observed for the first time. The branching fraction for the charged B--->phi K- gamma decay mode is measured to be B(B--->phi K- gamma)=(3.4+/-0.9+/-0.4)x10(-6). The photon energy distribution for the B--->phi K- gamma decay is presented. The signal for the neutral B(0)-->phi K(0)gamma decay mode is not statistically significant and an upper limit, B(B(0)-->phi K(0)gamma)<8.3x10(-6) at 90% C.L., is set. The analysis is based on a data set of 90 fb(-1) collected by the Belle experiment at the e(+)e(-) asymmetric collider KEKB.