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Pseudo-scalar glueball. Qi-Shu Yan Physics Department, Toronto University In collaboration with Song He and Mei Huang. A Viewpoint from the Effective Field Method Approach. 10:30am, 20, April, 2009 Center for High Energy Physics, Peking University. Outline. 1) Introduction
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Pseudo-scalar glueball Qi-Shu Yan Physics Department, Toronto University In collaboration with Song He and Mei Huang A Viewpoint from the Effective Field Method Approach 10:30am, 20, April, 2009 Center for High Energy Physics, Peking University
Outline • 1) Introduction • 2) An Effective Model of Instanton Effects • 3) Mass Spectra of the Model • 4) Model Parameters • 5) Numerical Results • 6) Conclusions
1 Introduction • Is it interesting to study hadron physics? • What’s U(1) problem of QCD? • Which pseudoscalar state is the exotic state? • Why effective theory method?
Hadron physics is a test field for our understanding on strong interaction system. • Hadron Physics is full of mysteries and exciting discoveries. • New Physics means exotic, hybrid, and multi-quark states. Glueball is one of the new physics.
Quarkonium Decays Central Production Proton-Antiproton Annihilation
Which state could be the ground state of pseudoscalar glueball? A Popular viewpoint: 1405 is a good glueball candidate.
1) Whether can the effective field theory method give an answer? 2) What’s the answer of the effective field theory method?
Why Effective Field Theory Method? • Model is needed due to the large mixing between pure glueball and quark states. • Chiral Quark Model is a useful and successful template model to understand symmetry breaking and meson properties. • It is a standard theoretical background for exotic states. • A workable model should describe both chiral symmetry breaking and U(1) problem solution.
Ideally, the effective field theory should be derived from the path integral. • Practically, the effective field theory is constructed by symmetries + part of exact result.
2 Effective Model Instanton induced term
Mass term for pseudo-glueball Mass term for pseudoscalar
Pseudoscalar ground state is heavier than scalar ground state.
Dimension Regularization can produce correct k parameter needed for the solution of U(1) problem
Schwinger-Dyson Equation method predicts two types of running effective gluon mass.
5 Numerical Analysis 8 free parameters in total
Scenario One Scenario Two
Mass splitting between scalar and pseudoscalar glueballs
6 Conclusion • The results of the effective field theory method are comparable with other methods. • Scalar and Pseudoscalar parts are correlated in the model. • In the first scenario, no experimental pseudoscalar can be glueball candidate. • In the second scenario, 1475, 1405, and 1295 are possible glueball candidate.