nLab QCD trace anomaly

Idea

While quantum chromodynamics (QCD) expressed via its Lagrangian density for quark-physics looks clasically like a conformal field theory, a quantum anomaly in the trace of its energy momentum tensor (conformal anomaly) breaks conformal invariance as a quantum field theory. This is called the QCD trace anomaly.

This is relevant in particular for computation of the equation of state of the quark-gluon plasma.

References

General

Original articles:

• R. J. Crewther, Nonperturbative evaluation of the anomalies in low-energy theorems, Phys. Rev. Lett. 281421 (1972) (doi:10.1103/PhysRevLett.28.1421)

• M. S. Chanowitz, John Ellis, Canonical Anomalies and Broken Scale Invariance, Phys. Lett. 40B397 (1972) (doi:10.1016/0370-2693(72)90829-5)

• M. S. Chanowitz, John Ellis, Canonical Trace Anomalies, Phys. Rev.D72490 (1973) (doi:10.1103/PhysRevD.7.2490)

• J. C. Collins, A. Duncan, S. D. Joglekar, Trace and Dilatation Anomalies in Gauge Theories, Phys. Rev.D16438 (1977) (doi:10.1103/PhysRevD.16.438)

Further discussion:

• Jens O. Andersen, Lars E. Leganger, Michael Strickland, The QCD trace anomaly, Phys.Rev. D84 (2011) 087703 (arXiv:1106.0514)

In geometric engineering of QCD on branes

Discussion via geometric engineering of QCD on intersecting branes (“holographic QCD”):

• Jose L. Goity, Roberto C. Trinchero, Holographic models and the QCD trace anomaly, Phys. Rev. D 86, 034033 – 2012 (arXiv:1204.6327)

• Aalok Misra, Charles Gale, The QCD Trace Anomaly at Strong Coupling from M-Theory (arXiv:1909.04062)

The QCD trace anomaly affects notably the equation of state of the quark-gluon plasma, see there at References – Holographic description of quark-gluon plasma