Research On Strange Hadron States In Radiative Deca

In recent years,many new hadron states beyond the conventional quark model have been experimentally discovered,and they are candidates for strange state hadrons.Many of these new hadron states lie near the mass threshold of a pair of charmed mesons or bottom mesons,which are candidates for hadron molecular states.The non-relativistic effective field theory approach is a popular treatment to study the properties of the exotic hadron states.Composition of matterThe first chapter briefly introduces the development history of particle physics and the basic composition of constituent substances.In the second chapter,the research methods and theoretical models used in this paper are briefly introduced,mainly including quantum chromodynamics,non-relativistic effective field theory and its fundamental integrals and power counting rules.In Chapter 3,we study the radiative decays Zc(3900)/Zc(4020)→γχcJ(γχ’cJ)(J=0,1,2),with the assumption that Zc(3900)and Zc(4020)couple strongly to DD*+c.c.and D*D*channels,respectively.By considering the contributions of intermediate charmed mesons triangle loops within an effective Lagrangian approach,it is shown that the calculated partial widths of Zc(3900)→γχcJ about a few hundred keV,while the obtained partial widths Zc(4020)→γχcJ about tens of keV.The predicted partial widths of Zc(3900)→γχ’c0,1 are less than 1 keV,which is mainly due to the very small phase space.For Zc(4020)→γχ’c0,2 the calculated partial widths are usually smaller than 1 keV.For the Zc(4020)→ γχ’c1 process,the obtained partial widths can reach up to the order of 10 keV.Furthermore,the dependence of these ratios between different decay modes on the masses of Zc(3900)and Zc(4020)are also investigated,which may be a good quantity for the experiments.It is hoped that the calculations here could be tested by future experiments.In Chapter 4,we investigate the production of Xb in the process(?)(5S,6S)→γXb,where Xb is assumed to be a BB*molecular state.Two kinds of meson loops of B(*)B(*)and B’1B(*)were considered.To explore the rescattering mechanism,we calculated the relevant branching ratios using the effective Lagrangian based on the heavy quark symmetry.The branching ratios for the(?)(5S,6S)→γXb were found to be at the orders of 10-7-10-6.Such sizeable branching ratios might be accessible at Bellell,which would provide important clues to the inner structures of the exotic state Xb.In Chapter 5,a summary of the article and an outlook on future work are given.