The decay of the observed J"P"C=1"-"+(1400) and J"P"C=1"-"+(1600) hybrid candidates

We study the possible interpretation of the two exotic resonances J"P"C=1"-"+ at 1400 and 1600 MeV, claimed to be observed by BNL, decaying respectively into #eta##pi#, #eta#'#pi#, f_1#pi# and #rho##pi#. These objects are interpreted as hybrid mesons, in the quark-gluon constituent model using a chromaharmonic confining potential. The quantum numbers J"P"CI"G=1"-"+1"- can be considered in a constituent model as an hybrid meson (qqg). The lowest J"P"C=1"-"+ states may be built in two ways: l_g=1 (gluon-excited) corresponding to an angular momentum between the gluon and (qq) system, while l_q _a_n_t_i _q=1 (quarks-excited) corresponds to an angular momentum between q and q. For the gluon-excited mode 1"-"+ hybrids, we find the decay dominated by the b_1#pi# channel, and by the #rho##pi# channel for the quark-excited mode. In our model, neither the quark-excited nor the gluon-excited 1"-"+ (1400 MeV) hybrids can decay into #eta##pi# and #eta#'#pi#, in contradiction with experiment. Hence, the 1400 MeV resonance seems unlikely to be an hybrid state. The 1"-"+ (1600 MeV) gluon-excited hybrid is predicted with too large a total decay width, to be considered as an hybrid candidate. On the contrary the quark-excited mode has a total decay width around 165 MeV, with a #rho##pi# preferred decay channel, in agreement with BNL. Our conclusion is that this resonance may be considered as a hybrid meson in the quark-excited mode. (orig.)Available from TIB Hannover: RA 2999(00-148) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman