Φπ production in $$\bar pp$$ annihilation from S and P states and in J/ψ decaysannihilation from S and P states and in J/ψ decays

Abstract

Recent experiments at LEAR have found surprisingly large branching ratios for reactions\(\bar NN \to \phi \pi \) from S-wave initial states while noφπ production is observed from P states of the\(\bar pp\) system. Also, noφπ is seen in radiative J/ψ decays even though the rate forωπ is substantial. We calculate theφπ production rates for these three cases viaKK* intermediate states and\(K\bar K\) rescattering using the dispersion relation technique; we find that the largeφπ rate in\(\bar pp\) annihilations from S states can be reproduced with a reasonable cut-off for the dispersion integral; for J/ψ decays the calculatedφπ rate is compatible with the observed upper limit. We would, however, expectφπ to be seen from\(\bar pp\) P-states, in contrast to experimental findings. Yet the branching ratio for\(\bar pp \to K*\bar K\) via isospinI = 1 of\(\bar pp\),1P1 state is not known; and therefore no definite conclusion can be drawn. We also compare the Dalitz plots we obtain for directφ production and forφ production via rescattering. Clear differences between the two theoretical distributions are observed; yet very high precision data would be required to establish the origin — direct production or rescattering — of theφ mesons. This observation supports the use of the isobar model in data analyses.