Theoretical Study Of The Excited Baryons Via Scattering And Decay Processes

With a chiral quark model,we studied the baryons properties via the scattering and decay processes.For the scattering processes,we studied the meson-induced scattering processes ?N??N and radiative-capture processes K-p???,??0.On the other hand,stimulated by the observation of five new Qc states and three bottom baryon?b(6227)-and ?b(6097)±,we systematically studied the decay properties of the single heavy baryons.our main results as follows:(?)By studying the ?N??N scattering processes,we find that:(i)in the chiral quark model,?(1232)P33 plays a crucial role in the ?+p??+p,?-p??-p and ?-p??0n reactions.The mass and width of ?(1232)P33 are determined to be M(?)1212 MeV and ?(?)100 MeV,respectively,which are quite close to the values determined with the pole parametrization from PDG.The ?(1232)N? coupling from the quark model is about a factor of 1.7 smaller than that extracted from the data,(ii)Confirmed roles of N(1440)P11 resonance are found in both the ?-p??-p and ?-p ?0n reactions.The extracted mass and width for N(1440)P1l are M(?)1400+-1920 MeV and ?(?)200+-3035,respectively,which are close to the values determined with the pole parametrization.The N(1440)N? coupling extracted from the data is a factor of?4.8 larger than the symmetric quark model prediction,(iii)Slight contributions of N(1535)S11 and N(1520)D13 are seen within the N(1440)resonance region in the ?-p??-p and?-p??0n reactions,and the s-channel nucleon pole,t-and u-channel backgrounds play remarkable roles.(?)By analyzing the K-p??? and K-p???0 reactions,we find that:(?)the?(1405)S01 resonance plays a dominant role in these two reactions,(?)We use the PDG data of ?(1520)D03??? and ?(1520)D03???0 to further predict the differential and total cross sections around the mass threshold of ?(1520)D03,respectively.It is found that A(1520).DO3 plays a important role and makes an obvious bump structure in the total cross section,(?)For the K-p???0 reaction,?(1670)S01 plays an important role and makes an obvious bump structure around the mass threshold of ?(1670)S01 in the total cross section.Our extracted partial widths of ?[?A(1670)S01???]and?[?(1670)S01???0]should be<1.5 keV and?3.98 MeV,respectively,(iv)The contact term background plays a crucial role in these two reactions.(?)By studying the decay properties of the single heavy baryons systematically in the L-S and j-j coupling scheme,we find that:(i)the properties of the five newly observed ?c states can be explained well.The ?c(3000)has Jp=1/2-and corresponds to the narrow IP mixed state |1P?1/2-)1.The ?c(3050)and ?c(3066)correspond to the IP states with JP=3/2-.Considering the mixing effect between |4P?3/2-?and|2P?3/2-}?the ?c(3050)and ?c(3066)seems to favor the |JP=3/2-,2} state and the|Jp=3/2-,1} state in the j-j coupling scheme,respectively.?c(3090)should corresponds to the JP=5/2-state |4P?5/2-}(|JP=5/2,2>).The ?c(3119)might correspond to one of the two states of the first radial excitations,i.e..|22S1/2+)or |24S??3/2+?.(?)transitions to ?b0? can have a branching fraction of O(10-2)and is an ideal channel for establishing them in experiments.(?)The newly observed two resonances ?b(6097)±and ?b(6227)-could be assigned to the JP=3/2-state |JP=3/2-,2>(|JP=3/2-,2>)or the Jp=5/2-state |JP=5/2-,2>(|JP=5/2-,2>).However,we cannot distinguish these two states,in order to identify them,angular distributions of their decays in either strong decay modes or radiative transitions should be observed in future ex-periments.(iv)Considering the mixing effect between |4P?3/2->and |2P?3/2->,the?c(2930)0 seems to favor the mixed state |?c' P1/2>2 in the ?c' family.The other mixed state |?c' P1/2->1 may be a relatively narrow state with a width of ?(?)16±5 MeV and the main decay channel ?c'?.(v)|?b2P?1/2-)and |?b2 P?3/2-)should be narrow states and mainly decay into the ?b'? and ?b'*? channels,respectively.