Production And Decays Of Hadrons At The Nonperturbative Energy Region

With a chiral quark model,we systematically studied the strong decay properties of the higher excited heavy-light mesons spectrum D,Ds,B and Bs,and presented our views for their classification and the future experimental observations.Meanwhile,we studied the photoproduction processes γN→π0N in the resonance energy region and the meson-induced scattering processes π-p→K0∧ and ηn,while presented our views for the long standing issues in nucleon resonances and scattering mechanism.A series of innovations been obtained and the details are as follows:(Ⅰ)By studying the strong decay properties of D,Ds,B and Bs mesons resonances,we find that:(i)Many missing resonances have good potentials to be found in the future experiments for their narrow widths(Γ～50-150 MeV),and some of them dominantly decay into the first orbital excitations;(ii)The newly observed state DJ(3000)could be identified as the low-mass mixed state |2P1)L(JP = 1+)via the 21P1-23P1 mixing,and seems to be a partner of the newly observed state DsJ(3040);the newly observed states DJ*(3000)may favor the 13F4 state,while the candidates with JP = 0+ and 2+cannot be excluded complectly;the newly observed states B(5970)is most likely to be the 13D3 state with JP = 3-.(II)In the study of the photoproduction processes γN→ π0N,we obtain that:(i)the resonancees △(1232)P33,N(1535)S11,N(1520)D13 and N(1720)P13 play vital roles in these processes.Experimental data below the third resonances energy region can be explained through the interferences between those resonances and the u-and t-channle backgrounds;(ii)Obvious evidence of △(1620)S31 and N(1650)S11 is found.They notably affect the polarization observables and the cross sections from the sec-ond resonance region up to the third resonance region.(iii)Meanwhile,we extract the helicity amplitudes of the main resonances,△(1232)P33,N(1535)S11,N(1520)D13,N(1720)P13,△(1620)S31,and N(1650)S11 for comparing with the results from other groups.(III)By studying the reactions π-p→ K0∧ and ηn,we find that:(i)the nu-cleon resonances N(1535)S11 and N(1650)S11 play crucial roles near the threshold.The N(1650)S11 has a relatively strong configuration mixing with N(1535)S11.The constructive interference between N(1535)S11 and N(1650)S11 is responsible for the peak structure at π-p→ K0A around threshold in the total cross section;(ii)The N(1520)D13 resonance affects the differential cross sections of the π-p →ηn reaction notably,while no obvious effects are seen in π-p→ K0∧ process.The experimental data of π-p→ K0∧ show that N(1720)P13 may have a large contribution.The width and mass of N(1720)P13 extracted by us are notably smaller than the values from the PDG,which need to be confirmed by the future experiments;(iii)The n-pole,u-,and t-channel backgrounds provide significant contributions to the π-p→ K0∧ process;while for π-p→ K0∧,one can see an obvious contribution from the u channel,which might explain a small bump structure appeared in π-p→ ηn around W(?)1.7 GeV by the interference with N(1650)S11.