Axial-Vector Current Anomaly, Decay Constants, and - '- c Problem in an N-Flavour Quark Model
Open Access
- 1 October 1978
- journal article
- Published by Oxford University Press (OUP) in Progress of Theoretical Physics
- Vol. 60 (4) , 1127-1143
- https://doi.org/10.1143/PTP.60.1127
Abstract
The η-η′ complex is treated in an N-flavour model of QCD. We consider the case that the underlying chiral U(N) ×U(N) symmetry is broken by quark masses and also by an anomalous term A5 (x;N) in the singlet axial-vector current divergence. We treat the term A5 phenomenologically and determine its matrix element between vacuum and the 0-th pseudoscalar boson state from known spectroscopy of physical 0--mesons. Setting up a natural model in which heavy quarks are approximately decoupled from the lighter ones, the above matrix element of A5 is seen to be proportional to the flavour number N. This N-dependence is confirmed empirically in realistic models for N = 3 and 4. Thus, the term A5 is naturally identified indentified with the Adler-Bell-Jackiw type anomaly coming from the quark-gluon coupling. Various decay constants of 0--mesons are also determined to be compared with experiment; all decay constants are roughly equal respecting flavour SU(4)-symmetry and the ηc(2.83) stays in an almost pure cKeywords
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