Study On The Mass Spectra Of Doubly Heavy Tetraquarks

The study of hadron spectrum is always an important way for people to understand the internal structure of various hadron.With the discovery of more and more hadrons experimentally,especially the doubly baryonΞcc,doubly heavy tetraquark Tcc and ful-l heavy tetraquark state,much attention has been paid to the spectrum and structure of hadrons.Through the study of hadronic spectra,we can not only better understand the internal interaction properties of hadronic states that have been found,but also make pre-dictions for other hadronic spectra and the corresponding partner states that have not been observed.In this paper we focus on the mass spectrum of the doubly heavy tetraquark state.In Chapter 1,we introduced the standard model and quark model of particles,and discussed the classification and interaction of the hadrons.Then we briefly introduce the experimental progress and theoretical model of heavy hadronic states.In Chapter 2,mass spectra of TQQ(QQ=cc、bb、bc)of the doubly tetraquark s-tate are studied systematically in the framework of the chromomagnetic interaction mod-el(CMI).By means of the mass expansion of the chromomagnetic interaction model,we analyze the known masses of hadron experimentally,and determine the coupling coeffi-cient Ai j of the chromomagnetic interaction term,the effective energy of the flux-tube Ei and the binding energy BQQ between two heavy quarks in the CMI model.Consider-ing the color mixing effect in the chromomagnetic interaction,the binding energy matrix and the sum of the color magnetic interaction matrix of the doubly tetraquark state are diagonalized,and the mass of the tetraquark state is predicted.Finally,the mass of Tcc with IJ~P=01~+,(?)3c(?)3c is 3879.2 Me V,which is very close to the experimental mass of 3874.7±0.05 Me V.Then,we further predict the masses of Tbband Tbcwith I=0/1,J~P=0~+/1~+/2~+.In Chapter 3,the mass spectrum of TQQ is compared with its corresponding thresh-old,and it is found that there are six stable tetraquark states,which are respectively Tbc with IJ~P=00~+;Tbb,Tbcwith IJ~P=01~+;Tbbwith IJ~P=10~+,IJ~P=11~+,IJ~P=12~+.In this paper,the mass of the Tcc of partner state with IJ~P=01~+is predicted to be about 4288 Me V by systematically studying the double tetraquark state TQQ,and its color is expressed as 6c(?)(?)6c,It is hoped that this strange color state and other TQQ states will also be tested experimentally.