Finite temperature effects and the validity of the Weinberg sum rules

19th Chilean Physics Symposium 2014

Ayala, Alejandro^1,3 ; Dominguez, C.A.^3 ; Loewe, M.^2,3,4 ; Zhang, Y.^5

Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apartado Postal 70-543, México Distrito Federal

04510, Mexico^1

Instituto de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago

22, Chile^2

Centre for Theoretical and Mathematical Physics, Department of Physics, University of Cape Town, Rondebosch

7700, South Africa^3

Centro Científico-Tecnológico de Valparaíso, Casilla 110-V, Valparaíso, Chile^4

CSIR National Laser Centre, PO Box 395, Pretoria

0001, South Africa^5

关键词: Axial vector;    Chiral symmetry;    Deconfinement;    Leading orders;    QCD sum rules;    Sum rule;    Thermal evolution;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/720/1/012024/pdf
DOI  :  10.1088/1742-6596/720/1/012024

来源: IOP

【 摘 要 】

Using resent independent results from QCD sum rules for the thermal evolution of hadronic parameters in the vector and the axial-vector channels, we discuss the saturation of the two Weinberg sum rules. It turn out that both sum rules are quite well satisfied in a wide range from T = 0 up to T/Tc 0.7 - 0.8. At higher temperatures, coming closer to Tc, there is an asymmetry between both channels since in the vector case there is a leading order effect, proportional to T2, due to a one loop pion contribution in the space-like region, which is absent in the axial-vector case. This leads then to a small deviation. More important, though, in this region the QCD sum rules for the hadronic parameters begin to have no solutions since the widths of the ρ and the a1-mesons diverge signaling the occurrence of deconfinement. Close to and at Tcthere are no pions left in the medium and chiral symmetry is restored so that the Weinberg sum rules are trivially satisfied.