The a_0(980), a_0(1450) and K_0~*(1430) scalar decay constants and the isovector scalar spectrum

摘要

The scalar correlator #PI#(q~2) = i integral d~4 x e~(iq centre dot x)<0|T(J(x)J(O))|O> (with J = partial deriv~#mu#(d-bar#gamma#~#mu#u)) is studied using a class of finite energy sum rules shown recently to be very well satisfied in the vector isovector channel. The values of the a_o scalar decay constants extracted in this analysis, which describe the couplings of the a_0(980) and a_0(1450) to the current J, are shown to be comparable, strongly disfavoring any scenario in which the a_0(980) is interpreted as a loosely bound KK-bar molecule and the a_0(1450) is assigned to the same flavor multiplet as the K_0~*(1430). The a_o decay constants are also compared to the analogous decay constant describing the coupling of the k_0~*(1430) to the divergence of the strange vector current, J_s = partial deriv_#mu#(s-bar#gamma#~#mu#u) (which may be obtained from experimental K_(e3) and K#pi# phase shift data) and implications of the relative magnitudes for the interpretation of the nature of the a_0 states discussed.