Phase transitions, θ behavior, and instantons in QCD and its holographic model
Abstract
In the holographic model of QCD, θ dependence sharply changes at the point of confinementdeconfinement phase transition. In large N QCD such a change in θ behavior can be related to the breakdown of the instanton expansion at some critical temperature T_{c}. Associating this temperature with confinementdeconfinement phase transition leads to the description of the latter in terms of dissociation of instantons into the fractionally charged instanton quarks. To elucidate this picture, we introduce the nonvanishing chiral condensate in the deconfining phase and assume a specific Lagrangian for the η^{'} field in the confining phase. In the resulting picture the hightemperature phase of the theory consists of the dilute gas of instantons, while the lowtemperature phase is described in terms of freely moving fractional instanton quarks.
 Publication:

Physical Review D
 Pub Date:
 December 2008
 DOI:
 10.1103/PhysRevD.78.125002
 arXiv:
 arXiv:0806.1736
 Bibcode:
 2008PhRvD..78l5002P
 Keywords:

 12.38.Aw;
 12.38.Lg;
 General properties of QCD;
 Other nonperturbative calculations;
 High Energy Physics  Phenomenology;
 High Energy Physics  Lattice;
 High Energy Physics  Theory
 EPrint:
 final version to appear in Phys. Rev. D