Expectation values of four-quark operators in pions

Abstract

The values of four-quark operators averaged over pions are expressed through those averaged over vacuum. The specific values are obtained in the framework of the factorization assumption. For the condensates of the light quarks of the same flavour \bar qΓq\bar qΓq the scalar condensate is shown to be an order of magnitude larger than the other ones. The condensates containing the strange quarks \bar q q\bar s s appear to be only about twice smaller than those of the light quarks. The degeneracy of the ground state in the Nambu--Jona--Lasinio model is shown explicitly.

9 pages, no figures, typos corrected

References in corpus (3)

• QCD Phenomenology based on a Chiral Effective Lagrangian
• QCD Sum Rules and Applications to Nuclear Physics
• The sigma term and the quark number operator in QCD

Cited by in corpus (6)

• A New Approach to Physics of Nuclei
• Nucleon QCD sum rules in nuclear matter including four-quark condensates
• Operator Product Expansion and Quark-Hadron Duality: Facts and Riddles
• Expectation values of four-quark operators in the nucleon
• Algebraic Approach to Bare Nucleon Matrix Elements
• The role of the in-medium four-quark condensates revised