Synopsis: Counting Photons in Quark-Gluon Plasma

A proposed mechanism for photon production in quark-gluon plasma can increase our understanding of its properties.
Synopsis figure
G. Başar et al., Phys. Rev. Lett. (2012)

Investigating quark-gluon plasma (QGP) is not trivial. Even finding out how hot it is presents difficulties. The yield of photons from the early formation stages of the plasma is a good “thermometer” for the QGP, and several detailed measurements have been made by collaborations at Brookhaven National Laboratory and the Large Hadron Collider. However, a precise theoretical understanding of the physical mechanisms driving this photon production is still lacking.

Now, in a paper published in Physical Review Letters, Gökçe Başar and colleagues at Stony Brook University, New York, and collaborators propose a mechanism for photon production in QGPs based on a well-known feature of QCD: the conformal anomaly. As a classical system, QCD possesses a special symmetry (conformal invariance) that is broken by quantum effects. Başar et al. show that the anomalous breaking of this symmetry in the presence of strong magnetic fields, such as the ones present in the QGP, can lead to a novel mechanism for photon production. They also show that an estimate of the photons produced through this mechanism corresponds to known experimental signals. However, further detailed analysis is needed to firmly understand the role of the proposed mechanism in the context of the QGP, and such results are eagerly awaited. – Abhishek Agarwal


Features

More Features »

Announcements

More Announcements »

Subject Areas

Nuclear Physics

Previous Synopsis

Interdisciplinary Physics

Networks Evolving on Two Fronts

Read More »

Next Synopsis

Graphene

Identification by Bonds

Read More »

Related Articles

Viewpoint: Watching the Hoyle State Fall Apart
Nuclear Physics

Viewpoint: Watching the Hoyle State Fall Apart

Two experiments provide the most precise picture to date of how an excited state of carbon decays into three helium nuclei. Read More »

Synopsis: Strong Force Calculations for Weak Force Reactions
Nuclear Physics

Synopsis: Strong Force Calculations for Weak Force Reactions

Theorists have used lattice-QCD calculations to predict two weak-force-driven reactions—proton fusion and tritium decay. Read More »

Synopsis: Proton Loses Weight
Particles and Fields

Synopsis: Proton Loses Weight

The most precise measurement to date of the proton mass finds a value that is 3 standard deviations lower than previous estimates. Read More »

More Articles