The Electromagnetic Properties Of Heavy Hadronic Molecule Pentaquarks

Studying the exotic hadronic states is an important research frontier full of opportunities and challenges in hadron physics.The study of the exotic hadronic states has opened a new chapter in hadron spectroscopy,provided a new opportunity for constructing the hadron family version 2.0,and played a vital role in studying the nonperturbative behavior of quantum chromodynamics(QCD).After the observation of the charmonium-like state X(3872)by Belle Collaboration in 2003,a series of new hadronic states had been reported by different experimental collaborations in the last two decades.Since the masses of some observed new hadronic states are close to the thresholds of two corresponding conventional hadronic states,it is natural to interpret them as molecular states.In particular,the LHCb Collaboration observed Pc(4312),Pc(4440)and Pc(4457)in Λb→J/ψpK process in 2019.This observation provided experimental evidence for the existence of hidden-charm molecular pentaquark states,and the molecular state has attracted the attention of theorists and experimenters as a configuration of exotic hadronic states.In this thesis,we first introduce the development of hadron physics and discuss the calculation method of the electromagnetic properties of conventional hadrons under the constituent quark model.We then proceed to investigate the electromagnetic properties such as magnetic moments,transition magnetic moments,and radiative decay widths of the heavy hadronic molecule pentaquarks in configurations of Σc(*)D(*)-type,Ξc(’)D*type,Ξc(’,*)Ds*-type,and Ωc(*)Ds*-type.The observation of the hidden-charm molecular pentaquark states Pc/Pcs and the doubly charmed molecular tetraquark state Tcc+ naturally makes our conjecture that there should exist the doubly charmed molecular pentaquark states composed of the charmed baryon ∑c(*)and the charmed meson D(*).Thus,we discuss the electromagnetic properties which have an intimate relation to their inner structures,both the S-D wave mixing effect and the coupled channel effect are taken into account.In the realistic calculation,we first analyze the magnetic moments of the S-wave Σc(*)D(*)molecular states,and then extend our theoretical framework to study the transition magnetic moments and the radiative decay widths between the S-wave Σc(*)D(*)molecules.Otherwise,we also discuss the relations between the magnetic moments and the transition magnetic moments of the S-wave Σc(*)D(*)-type doubly charmed molecular pentaquarks,which may be regarded as an indirect way to measure their magnetic moments experimentally.Inspired by the discovery of PψsΛ(4459)and PψsΛ(4338),we systematically promote the study of the electromagnetic properties of the hidden-charm molecular pentaquark states with strangeness.In the specific calculation,we discuss the electromagnetic properties such as magnetic moments,the transition magnetic moments,and the radiative decay behaviors of the S-wave Ξc(’)D*-type,Ξc(’,*)Ds*-type,Ωc(*)Ds*-type molecular pentaquark states,both the S-D wave mixing effects and the coupled channel effects are taken into account.The study of their electromagnetic properties can provide important information for understanding the inner structures of these hidden-charm molecular pentaquark states with strangeness.In past theoretical work,attention has been focused on the properties of the mass spectrum,the decay behaviors,and the production mechanisms of hadronic molecular states.Our work enriches the comprehension of the electromagnetic properties of heavy hadronic molecular states and plays an important role in revealing the inner structures of these heavy hadronic molecular states.Although it is hard to measure their electromagnetic properties such as magnetic moments experimentally,with the accumulation of experimental data and improvement of experimental precision,we hope to experimentally detect the electromagnetic properties of these heavy hadronic molecular pentaquark states.We also hope that more theoretical models will be available in the future to discuss the electromagnetic properties of heavy hadronic molecular states,which will provide important information for our comprehension of the inner structures of hadronic molecular states and the nonperturbative behaviors of QCD.