Journal of High Energy Physics

, 2017:151 | Cite as

Solving the Bars-Green equation for moving mesons in two-dimensional QCD

  • Yu Jia
  • Shuangran Liang
  • LiuJi Li
  • Xiaonu XiongEmail author
Open Access
Regular Article - Theoretical Physics


The two-dimensional QCD in the large N limit, generally referred to as the ’t Hooft model, is numerically investigated in the axial gauge in a comprehensive manner. The corresponding Bethe-Salpeter equation for a bound \( q\overline{q} \) pair, originally derived by Bars and Green in 1978, was first numerically tackled by Li and collaborators in late 1980s, yet only for the stationary mesons. In this paper, we make further progress by numerically solving the Bars-Green equation for moving mesons, ranging from the chiral pion to charmonium. By choosing several different quark masses, we computed the corresponding quark condensates, meson spectra and their decay constants for a variety of meson momenta, and found satisfactory agreement with their counterparts obtained using light-cone gauge, thus numerically verifed the gauge and Poincaré invariance of the ’t Hooft model. Moreover, we have explicitly confirmed that, as the meson gets more and more boosted, the large component of the Bars-Green wave function indeed approaches the corresponding ’t Hooft light-cone wave function, while the small component of the wave function rapidly fades away.


1/N Expansion Field Theories in Lower Dimensions 


Open Access

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© The Author(s) 2017

Authors and Affiliations

  1. 1.Institute of High Energy Physics and Theoretical Physics Center for Science FacilitiesChinese Academy of SciencesBeijingChina
  2. 2.School of PhysicsUniversity of Chinese Academy of SciencesBeijingChina
  3. 3.Center for High Energy PhysicsPeking UniversityBeijingChina
  4. 4.Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron PhysicsJülichGermany
  5. 5.Istituto Nazionale di Fisica Nucleare, Sezione di PaviaPaviaItaly

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