A Monte Carlo Study on the Identification of Quarkgluon Fusion Product in QCDinstanton In.pdfVIP

A Monte Carlo Study on the Identification of Quark-gluon Fusion Product in QCD-instanton Induced Processes in Deep-inelastic Scattering Xu Mingmei and Liu Lianshou∗1 1Institute of Particle Physics, Huazhong Normal University, Wuhan 430079, China Different methods to reconstruct the quark-gluon fusion product and current jet are tried in deep-inelastic e-p scattering events with instanton as background generated by QCDINS Monte Carlo code. A comparison of these methods are performed and a good method is found which can reconstruct well the energies of current jet and instanton product as well as the mass of the latter. The isotropy property of the instanton product and jet are calculated and compared. A parameter characterizing the degree of “hardness” of the instanton product is presented. PACS numbers: 13.85.Hd; 13.60.-r; 05.45.Yv; 05.10.Ln 6 0 0 I. INTRODUCTION 2 t c In the Standard Model, both the strong and O the electro-weak interactions are described by non- Abelian gauge theory. In these theories, the ground 8 1 state has a rich topological structure, associated with non-perturbative fluctuations of the gauge field, 1 called instantons [1, 2, 3, 4], which represent tunnel- v ing transition between topologically non-equivalent 4 vacua. In the strong sector, described by QCD, 4 instantons are non-perturbative fluctuations of the 2 gluon field. Deep-inelastic scattering (DIS) offers 0 1 a unique opportunity to discover the processes in- 6 duced by QCD instantons.