Quasi-linear Mass Formula For Light Mesons In Quark Model

In particle physics,hadron is composite particle which composed by quarks that are bound together by strong interaction,hadrons are the smallest units with internal structures that can be fragmented and observed.The hadron spectrum,as an observable measure of hadron structure,is a powerful tool for exploring the microstructure of matter.In this paper,the auxiliary field method is applied to the quasi-relativistic quark model to obtain a light mesonic mass formula which is flavor-dependent.The model parameters of the light mesonic mass formula are obtained by fitting the experimental data in the particle data group.we compare the predictions of the mass formula with the experimental values and other the calculation in the literatures.The results show that the mass of low excitations fit by the mass formula are in good agreement with the experimental data and the average error is around 30 Me V.This method is extended to heavy-light meson,and obtain an heavy-light mesonic mass formula and Regge relatons.The main contents are as follows:The first chapter briefly introduces the basic knowledge of particle physics,including the interactions and classification of particles,and gives a standard model of the fundamental particles;Secondly,we introduce the nature of QCD and the quark model of hadrons(mainly Godfrey-Isgur model)as well as other theoretical methods,including lattice QCD,QCD sum rules,large NcQCD;Next,we present the Regge Theory of hadron spectrum;Finally,the latest experimental progress of particle physics is introduced.In the second chapter,we mainly introduce the QCD string model whose relation to Regge Trajectory is explained and gives the mass formula of the light meson in the string model.Then we introduce the auxiliary field method,begin with free relativstic point particle,the square root of the relativistic form of Lagrangian is removed and transformed Lagrangian into an analytic form.In the third chapter,we mainly study the mass spectrum of the light meson in the relativistic quark model.Using the auxiliary field method,we obtain amass formula of the light mesons in the relativistic rotating string model.The results show that the mass of low excitations fit by the mass formula are in good agreement with the experimental data and our mass predictions for the high states als agree well with the other calculatins in the literatures,particularly the string model calculations.In the fourth chapter,we study the mass spectrum of the heavy-light mesons.In the same way,with the help of auxiliary field method,we obtain the slope of the heavy-light meson and the light-light meson is 2:1.Then combine Regge theory,we obtain heavy-light mesonic mass formula and Regge relations.In the fifth chapter,we summarize the work we have done and at the same time we give a prospect of our future work.