The B parameter beyond the leading order of the 1 N expansion

William A. Bardeen, A. J. Buras, J. M. Gerard

Research output: Contribution to journalArticlepeer-review

135 Scopus citations


We calculate the next-to-leading 1 N corrections to the B parameter which measures the size of the ΔS=2 matrix element 〈K0|(sd)V-A(sd)V-A|K0〉. These corections turn out to be small which assures the validity of the 1/N expansion. For ΛQCD=0.3GeV we find B=0.66±0.10 to be compared with the leading order value B=0.75. We clarify the differences between these results and the results of the usual chiral perturbative calculations which give |B|≈ 1 3 at the tree level but appear to signal the breakdown of chiral perturbation theory at the one-loop level.

Original languageEnglish
Pages (from-to)343-349
Number of pages7
JournalPhysics Letters B
Issue number3
StatePublished - 1 Sep 1988
Externally publishedYes


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