Quark models for mesons

Jialun Ping^1a, Chengrong Deng², Hongxia Huang¹, Fangfang Dong¹ and Fan Wang³

¹ Department of Physics, Nanjing Normal University, Nanjing 210097, P.R. China
² School of Mathematics and Physics, Chongqing Jiaotong University, Chongqing 400074, P.R. China
³ Department of Physics, Nanjing University, Nanjing 210093, P.R. China

^a e-mail: jlping@njnu.edu.cn

Published online: 10 February 2012

Abstract

With the advance of experiment, many high excited states of meson are identified. It is found that many of them are difficult to fit into conventional q meson spectra. Various explanations are proposed. One of them is the four-quark states or molecules of two mesons. In the framework of quark model, by taking into account of multi-body interaction, four-quark states are studied. The results show that the scalar mesons: f₀(600), f₀(980) and Y(2175) can be well described by four-quark states. Furthermore, unquenched quark model, which incorporates the four-quark components in the conventional q states, is constructed for mesons. By readjusting the model parameters, the model can give a good description of mesons. The model is also used to study the newly discovered XYZ particles.