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\(N_f\) dependence of the quark condensate from a chiral sum rule

  • B. Moussallam
Theoretical physics

Abstract.

How fast does the quark condensate in QCD-like theories vary as a function of \(N_f\) is inferred from real QCD using chiral perturbation theory at order one loop. A sum rule is derived for the single relevant chiral coupling constant, \(L_6\). A model independent lower bound is obtained. The spectral function satisfies a Weinberg-type superconvergence relation. It is discussed how this, together with chiral constraints, allows a solid evaluation of \(L_6\), based on experimental \(\pi\pi\)\(K\bar K\)S-wave T-matrix input. The resulting value of \(L_6\) is compatible with a strong \(N_f\) dependence possibly suggestive of the proximity of a chiral phase transition.

Keywords

Perturbation Theory Phase Transition Strong Dependence Spectral Function Chiral Perturbation Theory 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • B. Moussallam
    • 1
  1. 1.I.P.N., Groupe de Physique Théorique, Université Paris-Sud, 91406 Orsay Cédex, France FR

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