Mesonic fluctuations in a nonlocal Nambu–Jona-Lasinio model

✍ Scribed by Robert S. Plant; Michael C. Birse

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 244 KB
• Volume: 703
• Category: Article
• ISSN: 0375-9474
• DOI: 10.1016/s0375-9474(01)01669-4

✦ Synopsis

The effects of meson fluctuations are studied in a nonlocal generalization of the Nambu-Jona-Lasinio model, by including terms of next-to-leading order (NLO) in 1/N c . In the model with only scalar and pseudoscalar interactions NLO contributions to the quark condensate are found to be very small. This is a result of cancellation between virtual mesons and Fock terms, which occurs for the parameter sets of most interest. In the quark self-energy, similar cancellations arise in the tadpole diagrams, although not in other NLO pieces which contribute at the ∼ 25% level. The effects on pion properties are also found to be small. NLO contributions from real ππ intermediate states increase the sigma-meson mass by ∼ 30%. In an extended model with vector and axial interactions, there are indications that NLO effects could be larger.