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 πN→πN and radiative-capture processes K-p→Ο∧,γ∑0.On the other hand,stimulated by the observation of five new Qc states and three bottom baryonΞb(6227)-and ∑b(6097)±,we systematically studied the decay properties of the single heavy baryons.our main results as follows:(Ⅰ)By studying the πN→πN scattering processes,we find that:(i)in the chiral quark model,△(1232)P33 plays a crucial role in the π+p→π+p,π-p→π-p and π-p→π0n reactions.The mass and width of △(1232)P33 are determined to be M(?)1212 MeV and Γ(?)100 MeV,respectively,which are quite close to the values determined with the pole parametrization from PDG.The △(1232)Nπ 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 π-p→π-p and π-p π0n reactions.The extracted mass and width for N(1440)P1l are M(?)1400+-1920 MeV and Γ(?)200+-3035,respectively,which are close to the values determined with the pole parametrization.The N(1440)Nπ 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 π-p→π-p andπ-p→π0n reactions,and the s-channel nucleon pole,t-and u-channel backgrounds play remarkable roles.(Ⅱ)By analyzing the K-p→γ∧ and K-p→γ∑0 reactions,we find that:(ⅰ)the∧(1405)S01 resonance plays a dominant role in these two reactions,(ⅱ)We use the PDG data of ∧(1520)D03→γ∧ and ∧(1520)D03→γ∑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,(ⅲ)For the K-p→γ∑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 Γ[∧A(1670)S01→γ∧]andΓ[∧(1670)S01→γ∑0]should be<1.5 keV and～3.98 MeV,respectively,(iv)The contact term background plays a crucial role in these two reactions.(Ⅲ)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 Ωc states can be explained well.The Ωc(3000)has Jp=1/2-and corresponds to the narrow IP mixed state |1Pλ1/2-)1.The Ωc(3050)and Ωc(3066)correspond to the IP states with JP=3/2-.Considering the mixing effect between |4Pλ3/2-。and|2Pλ3/2-}，the Ωc(3050)and Ωc(3066)seems to favor the |JP=3/2-,2} state and the|Jp=3/2-,1} state in the j-j coupling scheme,respectively.Ωc(3090)should corresponds to the JP=5/2-state |4Pγ5/2-}(|JP=5/2,2>).The Ωc(3119)might correspond to one of the two states of the first radial excitations,i.e..|22S1/2+)or |24Sλλ3/2+。.(ⅱ)transitions to ∧b0γ can have a branching fraction of O(10-2)and is an ideal channel for establishing them in experiments.(ⅲ)The newly observed two resonances ∑b(6097)±and Ξb(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 |4Pλ3/2->and |2Pλ3/2->,theΞc(2930)0 seems to favor the mixed state |Ξc’ P1/2>2 in the Ξc’ family.The other mixed state |Ξc’ P1/2->1 may be a relatively narrow state with a width of Γ(?)16±5 MeV and the main decay channel Ξc’π.(v)|Ξb2Pλ1/2-)and |Ξb2 Pλ3/2-)should be narrow states and mainly decay into the Ξb’π and Ξb’*π channels,respectively.