Abstract
A new mechanism of photon emission in the quark-gluon plasma is proposed. Photon dispersion relation in the presence of the $CP$-odd topological regions generated by the chiral anomaly acquires an imaginary mass. It allows photon radiation through the decay $q\to q\gamma$ and annihilation $q\bar q\to \gamma$ processes closely related to the chiral Cherenkov radiation. Unlike previous proposals this mechanism does not require an external magnetic field. The differential photon emission rate per unit volume is computed and shown to be comparable to the rate of photon emission in conventional processes.
Highlights
Photon radiation by hot nuclear matter has been a focus of experimental and theoretical studies for many decades
In spite of considerable progress, there are still unresolved problems concerning the photon spectrum produced in relativistic heavy ion collisions, such as the puzzling enhancement of the direct photon production [1,2]
The main result of this paper are Eqs. (20) and (33) that represent the differential rates of photon emission rate by means of the chiral Cherenkov radiation in the decay and annihilation channels
Summary
Photon radiation by hot nuclear matter has been a focus of experimental and theoretical studies for many decades. It appears in the modified Maxwell equations as the spatial and the temporal derivatives of θ It has been known since the pioneering article by Carroll, Feld, and Jackiw [28] that in QED coupled to the axion field, photons acquire an imaginary mass mA making possible their spontaneous emission by fermions. [31,32] where one is free to choose the quark energy high enough so that most of the photon spectrum satisfy |mA| ωpl, in the case of QGP the bulk of the photon radiation occurs at ω T , where T is the QGP temperature Still, it is argued that at high enough temperatures, the photon mass satisfies the second assumption since the plasma frequency is proportional to T , see Eq (8), whereas the absolute value of mA2 is proportional to the sphaleron transition rate which rises at high temperatures as T 4.
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