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Photo of Johan Bijnens

Johan Bijnens

Professor

Photo of Johan Bijnens

The BK parameter in the 1/Nc expansion

Author

  • Johan Bijnens
  • Joaquím Prades

Summary, in English

We calculate the BK parameter within the framework of the 1/Nc expansion. We essentially use the technique presented by Bardeen, Buras and Gérard but calculate an off-shell Green function in order to disentangle different contributions. We study this Green function in pure Chiral Perturbation Theory (CHPT) first and afterwards in the 1/Nc expansion in the presence of an explicit cut-off to determine BK and the counterterms appearing in CHPT The high energy part is done using the renormalization group. For the low-energy contributions we use both CHPT and an Extended Nambu-Jona-Lasinio model. This model has the right properties to match with the high energy QCD behaviour. We then study explicit chiral symmetry breaking effects by calculating with both massless and degenerate quarks together with the real case. A detailed analysis and comparison with the results found within other approaches is done. Consequences for present lattice calculations of this parameter are then obtained. As final result we get 0.60 < B ̂K < 0.80. If ms = md = 0 we get 0.25 < B ̂Kx < 0.55.

Publishing year

1995-06-26

Language

English

Pages

523-562

Publication/Series

Nuclear Physics, Section B

Volume

444

Issue

3

Document type

Journal article

Publisher

North-Holland

Topic

  • Subatomic Physics

Status

Published

ISBN/ISSN/Other

  • ISSN: 0550-3213