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


More Announcements »

Subject Areas

Nuclear Physics

Previous Synopsis

Interdisciplinary Physics

Networks Evolving on Two Fronts

Read More »

Next Synopsis


Identification by Bonds

Read More »

Related Articles

Viewpoint: Cavity with Iron Nuclei Slows Down X Rays

Viewpoint: Cavity with Iron Nuclei Slows Down X Rays

Slow light effects have been measured for x rays using a cavity filled with iron nuclei, where the speed of light was reduced by a factor of 10,000. Read More »

Viewpoint: Cyclotron Radiation from One Electron
Particles and Fields

Viewpoint: Cyclotron Radiation from One Electron

An electron’s energy can be determined with high accuracy by detecting the radiation it emits when moving in a magnetic field. Read More »

Synopsis: Fixing a Million-Year Clock

Synopsis: Fixing a Million-Year Clock

A better measure of an iron isotope’s half-life may lead to new ways of dating astrophysical events that unfold over millions of years. Read More »

More Articles