Charm-changing weak neutral currents

Abstract

The observation (1) of the reaction ~+e--+~+e- suggests the existence of an interaction term (~v~)(~e). It is generally accepted that e-~ universality holds in weak charged currents, however it is still not established for weak neutral currents. In this note we investigate the possibility of observation of charm-changing neutral currents, which have been pointed out by NA~AGAWA (2) and the present author (3) from the standpoints of the lepton-urbaryon correspondence and of a composite model, respectively. Firstly, we discuss charmed-baryon production by highenergy neutrino beams v~. Next, we discuss the decays of the vector meson D~ (= (PoPo +PoPo)/~/~) into lepton pairs. i) Violation of e-t~ universality in neutral currents and charm-changing neutral currents. Let us show that charm-changing neutral currents are induced in the semi leptonie process if the e-~ universality is violated in leptonic neutral currents. We start from the following Hamiltonian of the pure leptonie weak interaction: (]) + 2e(~v~)(~ve) + d ((~v~)2_r (~v~)2) + 2e(fi#)(~e) + ]((fi#)2 + (~e)2), where j = (~e)+ (~/~) and Lorentz indices are omitted. Here we require e-~ universality for the Hamiltonian. If we require it for the currents, we get a =  b, c = i d and e =  ], where the positive and negative signs correspond to e-~ symmetry and e-~ antisymmetry in the leptonic currents, respectively.