Apr 23 – 27, 2023
JMS Aster Plaza
Asia/Tokyo timezone

The direct photon puzzle and the weak magnetic photon emission

Apr 24, 2023, 2:40 PM
Multi-Purpose Studio, 2nd Floor (JMS Aster Plaza)

Multi-Purpose Studio, 2nd Floor

JMS Aster Plaza

Oral Electromagnetic probes Parallel Session C


Jing-an Sun (Fudan University) Li Yan (Fudan University)


We propose a novel effect that accounts for the photon emission from a quark-gluon plasma in the presence of a weak external magnetic field. Although the weak magnetic photon emission from quark-gluon plasma only leads to a small correction to the photon production rate, the induced photon spectrum can be highly azimuthally anisotropic, as a consequence of the coupled effect of the magnetic field and the longitudinal dynamics in the background medium. With respect to a realistic medium evolution containing a tilted fireball configuration, the direct photon elliptic flow from experiments is reproduced. In comparison to the experimental data of direct photon elliptic flow, in heavy-ion collisions, the magnitude of the magnetic field at very early stages can be extracted. For the top energy of RHIC collisions, right after the pre-equilibrium evolution, |eB| is found no larger than a few percent of the pion mass square.[arxiv:2302.07696]

Theory / experiment Theory

Primary authors

Jing-an Sun (Fudan University) Li Yan (Fudan University)

Presentation materials