English

U_A(1) anomaly and eta' mass from an infrared singular quark-gluon vertex

High Energy Physics - Phenomenology 2008-12-18 v2 Nuclear Theory

Abstract

The UA(1)U_A(1) problem of QCD is inevitably tied to the infrared behaviour of quarks and gluons with its most visible effect being the η\eta^\prime mass. A dimensional argument of Kogut and Susskind showed that the mixing of the pseudoscalar flavour-singlet mesons with gluons can provide a screening of the Goldstone pole in this channel if the full quark-quark interaction is strongly infrared singular as 1/k4\sim 1/k^4. We investigate this idea using previously obtained results for the Landau gauge ghost and gluon propagator, together with recent determinations for the singular behaviour of the quark-gluon vertex. We find that, even with an infrared vanishing gluon propagator, the singular structure of the quark-gluon vertex for certain kinematics is apposite for yielding a non-zero screening mass.

Keywords

Cite

@article{arxiv.0804.3478,
  title  = {U_A(1) anomaly and eta' mass from an infrared singular quark-gluon vertex},
  author = {Reinhard Alkofer and Christian S. Fischer and Richard Williams},
  journal= {arXiv preprint arXiv:0804.3478},
  year   = {2008}
}

Comments

8 pages, 4 figures. Version to appear in EPJA