Study On Semileptonic Λ_b→(?)_llΛ_c~* Decays And The Structure Nature Of Λ_c(2595) And Λ_c(2625)

The properties and internal structure of hadrons and the strong interaction be-tween hadrons are the key topics of hadron physics research.Most of the hadrons found experimentally are ordinary hadronic states,that is,mesons with qq compo-nents or baryons with qqq components.In addition to ordinary hadronic states,the existence of so-called exotic hadrons is theoretically allowed,including:multi-quark states or molecular states,hybrid states,and glueball.The study on exotic hadrons can not only enrich the existing hadron spectrum。but also help us further understand and improve the theory of strong interactionΛc(2595)and Λc(2625)are excited states of charmed baryon with isospin I = 0,and with spin-parity JP = 1/2 or 3/2-.They are considered as candidates of ex-otic hadrons.In the framework of the chiral unitary approach and the local hidden gauge theory,Λc(2595)and Λc(2625)can be dynamically generated from the interac-tion of meson-baryon with open charm,having the structure nature of meson-baryon molecular states.The most important structural component of AC(2625)is D*N.and Λc(2595)couples mostly to DN,D*N channelsIn this thesis,basing on the view point that Λc(2595)and Λc(2625)are dy-namically generated from the DN and D*N interaction with coupled channels,the production rates of A,(2595)and Λc(2625)in the semileptonic Ab→(?)_llΛc*[Λc*≡Λc(2595)or AG(2625)]decays,with the aim of testing the molecular picture for Λc(2595)and Λc(2625).From the reaction mechanism on quark level for Ab→(?)_ll→c*decay,the DN,D*N states are produced right after the hadronization,creating a qq pair with the quantum numbers of the vacuum.And then the Ac*state is generated dynamically from the rescattering of DN.D*N and their coupling channels.Using the couplings ofΛc(2595)and Λc(2625)states to the DN,D*N coupled channels as inputs,the transi-tion amplitude of Ab→(?)_llΛc*decays are obtained,containing the information of the structure nature A*state.The ratio of Γ[Λb→(?)_llΛc(2595)]/Γ[Λb→(?)_llΛc(2595)] is evaluated,cancelling the un-known factor involving the vertices of weak interaction.It is found that the theoretical result is in agreement with the experiment within errors.Corrections from relativistic effect and the DsΛ,Ds*Λ channels are also investigated.It is shown that the relativistic correction is rather small,and the including of the DsΛ,Ds*Λ channels made the a-greement better with the cental value f the experimental results.The results obtained with these reactions give support to the molecular picture for these two Ac*resonances.