arXiv subjects

Nandagopal Vijayakumar

Publications and source records attributed to Nandagopal Vijayakumar.

4 recordsLinked to original sources

arXiv2026

Rotating synchrotron radiation: Photon emission from magnetized and rotating quark-gluon plasma

This paper investigates the production of non-prompt photons originating from rotating synchrotron radiation (RoSyRa), specifically the emission of photons by a rigidly rotating quark-gluon plasma in thermal equilibrium, in the presence of an external magnetic field. We compute the non-prompt photon spectrum and its elliptic flow ($v_2$) at mid-rapidity. In particular, we investigate the finite volume effects. We find that at low transverse momentum, the magnetic field induces a significant $v_2$, while the plasma rotation boosts the synchrotron radiation of negatively charged quarks. These findings make RoSyRa a viable candidate mechanism to resolve the "direct photon puzzle."

hep-ph↗

arXiv2025

Quasi-Classical Approximation of Electromagnetic Radiation by Fermions embedded in Rigidly Rotating Medium in Strong Magnetic Field

We develop the quasi-classical (WKB) approximation of the synchrotron radiation by a fermion embedded into uniformly rotating system in external magnetic field. We show that it gives an accurate approximation of the exact expression that we recently obtained at a tiny fraction of the numerical cost. Our results can be used to compute the electromagnetic radiation of the quark-gluon plasma produced in relativistic heavy-ion collisions.

hep-ph↗

arXiv2023

Photon radiation by relatively slowly rotating fermions in magnetic field

We study the electromagnetic radiation by a fermion carrying an electric charge $q$ embedded in a medium rotating with constant angular velocity $\bfΩ$ parallel or anti-parallel to an external constant magnetic field $\bf B$. We assume that the rotation is "relatively slow"; namely, that the angular velocity $Ω$ is much smaller than the inverse magnetic length $\sqrt{qB}$. In practice, such angular velocity can be extremely high. The fermion motion is a superposition of two circular motions: one due to its rigid rotation caused by forces exerted by the medium, another due to the external magnetic field. We derive an exact analytical expression for the spectral rate and the total intensity of this type of synchrotron radiation. Our numerical calculations indicate very high sensitivity of the radiation to the angular velocity of rotation. We show that the radiation intensity is strongly enhanced if $q\bf B$ and $\bf Ω$ point in the opposite directions and is suppressed otherwise.

hep-ph↗

arXiv2023

Synchrotron radiation by slowly rotating fermions

We study the synchrotron radiation emitted by a charged fermion, rotating as a part of a larger system, in a constant magnetic field $B$ parallel to the axis of rotation. The rotation is classical and independent of the magnetic field. The angular velocity of rotation $Ω$ is assumed to be much smaller than the inverse magnetic length $\sqrt{qB}$ which allows us to ignore the boundary effects at $r=1/Ω$. We refer to such rotation as slow, even though in absolute value it may be an extremely rapid rotation. Using the exact solution of the Dirac equation we derived the intensity of electromagnetic radiation, its spectrum and chirality. We demonstrate by explicit numerical calculation that the effect of rotation on the radiation intensity increases with the particle energy. Depending on the relative orientation of the vectors $\bfΩ$ and $\bf B$ and the sign of the electric charge, the rotation can either strongly enhance or strongly suppress the radiation.

hep-ph↗