The Properties Of The Resonances In The Decays Of Hadrons

Hadrons are composite particles composed of quarks and gluons,and it is the smallest unit that people can split out in the experiments.The properties of hadrons are described by the non-perturbation behavior of quantum chromodynamics(QCD),therefore,it is of great importance to study the properties of hadrons in order to further understand the non-perturbation behavior of QCD.In last decades,a large amount of information about the hadronic resonances have been accumulated experimentally.How to understand the properties of the resonance states by interpreting experimental data is one of the important research directions in hadron physics.In this paper we will study the properties of the hadronic resonance states by analyzing the relevant hadronic decay process,including the following five contents:1.The strong decay properties of a0(1950)and a0(2020)are studied to explore their possibility as excited states of ordinary scalar mesons.We calculate the strong decay of a0(1950)and a0(2020)within the 3P0 model by assuming that a0(1450)is the ground isovector scalar meson.Combined with the mass prediction of the quark model,for scalar meson excited states,our results show that a0(1950)and a0(2020)can be considered as the same state,both of which are a0(3 3PO)state The masses and strong decays of a0(2 3P0)and a0(4 3P0)are also predicted,which can be useful in the search for radially excited scalar mesons in the future.2.Within the chiral unitary approach,the axial-vector resonance K1(1270)has been predicted to manifest a two-pole nature,that is,different poles are mainly coupled to different vector-pseudoscalar(VP)channels.We analyze theoretically how this double-pole structure can show up in the D0??+VP decays.By looking at the vector-pseudoscalar(VP)invariant mass distribution for different VP channels,we find that each pole couples differently to different VP pairs,that is,this process can be used to observe the two poles of K1(1270).This work provides a theoretical basis for the experimental study of the double poles structure of the K1(1270)resonance.3.BES? experiment recently measured the invariant mass distribution of D+?ve+K?? process.Based on the last work,we analyze D+?ve+VP reaction to study the two poles of K1(1270)resonance,which has important guiding significance for the further analysis of the experiment.4.One of the defining features associated to the molecular states that couple to several hadron-hadron channels is that one can find a strong cusp in one of the weakly coupled channels at the threshold of the channel corresponding to the main component of the molecular state.Based on this property,we study the B+?J/??K+ reaction,and show that it is driven by the presence of two resonances,the X(3940)and X(3930),that are of molecular nature and couple most strongly to D*D*but also to J/??.Because of that,in the J/?? mass distribution we find a peak related to the excitation of the resonances and a cusp with large strength at the D*D*threshold.This work further validates a method for determining molecular states.5.The enhancement structure near the threshold is complicated to explain,and there are many reasons for its formation.In this work,we have analyzed the reaction Xc0?pK+? reported by the BES? Collaboration,taking into account the contributions from the intermediate K(1830),N(2300),and ?(1520)resonances.Our results are well consistent with the BES? measurements,and it is found that the anomalous enhancement near the p? threshold is mainly due to the contribution of the K(1830)resonance.We also show that the interference of the high-mass N*and ?*can not produce the anomalous enhancement near the p? threshold.This work is helpful to understand the enhancement near p? threshold.In conclusion,by studying the strong decay and weak decay processes of several hadrons,this paper discusses the properties of the resonant states a0(1950),a0(2020),K1(1270),X(3940),X(3930),and K(1830),which helps us to deepen our understanding of the nature of these resonances and provides some theoretical guidance for the experimental study of their properties.