Searcharxiv⌕ Search

arXiv subjects

Kirill Tuchin

Publications and source records attributed to Kirill Tuchin.

At least 19 recordsLinked to original sources
arXiv2026

Photon emission from rotating plasmas: a generalized McLerran-Toimela formula and the onset of superradiance

The photon emission and absorption spectra of a plasma rotating with constant angular velocity $\Omega$ are derived in terms of the spectral function of the current--current correlator. In contrast to the non-rotating case, the leading contribution arises already at one-loop order. The photon emission spectrum and its elliptic flow are calculated for a rotating quark--gluon plasma and compared with the leading two-loop result for a non-rotating plasma. The rotating plasma is found to emit significantly more soft photons than the non-rotating one. An analysis of the emission and absorption of cylindrical waves indicates that photons with energy $\omega$ and azimuthal quantum number $m$ satisfying $\omega<m\Omega$ are emitted at a higher rate than they are absorbed, thereby exhibiting the phenomenon of superradiance. It is further argued that these superradiant modes induce an instability of the magnetic field that is generated concurrently with the plasma in relativistic heavy-ion collisions.

hep-ph↗
arXiv2026

Scattering Amplitudes and Resonant Processes in QED with Chiral Chemical Potential and Chiral Magnetic Conductivity

The QED scattering amplitude in a chiral medium characterized by a constant chiral chemical potential $\mu_5$ and chiral magnetic conductivity $b_0$ is analyzed. We show the emergence of the resonant behavior in $1\to 2$, $2\to 2$, and $2\to 3$ processes. We compute the rates of paradigm $1\to 2$ processes that determine the widths of quasi-stationary fermion and photon states in the medium. We elucidate the origin of these resonances, the conditions of their emergence, and the physical principles of their regularization.

hep-ph↗
arXiv2026

Quark and gluon production in the presence of the time-varying chiral magnetic current

The chiral magnetic effect consists in the induction of the electric current along the direction of the magnetic field. The corresponding transport coefficient $b_0$, known as the chiral magnetic conductivity, is proportional to the chiral imbalance in the medium. In many systems, such as quark-gluon plasma, $b_0$ is time-dependent. This paper studies the effect of the time variation of $b_0$ on the particle spectra and energy loss produced through the chiral Cherenkov and associated processes in Abelian and non-Abelian systems. The rates of all processes are derived in the ultra-relativistic approximation. The results are applied to the relativistic heavy-ion collisions utilizing a specific model describing the relaxation of the initial $P$-odd domain within the quark-gluon plasma. The corresponding energy loss is computed. The results suggest strong polarization of jets in quark-gluon plasma.

hep-ph↗
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↗
arXiv2026

Searching for missing direct photons in heavy-ion collisions with P and CP violation

We compute synchrotron radiation from a plasma in which $P$- and $CP$-violating parameters, a chiral chemical potential and a chiral gradient, couple to fermions. To do this, we compute exact wavefunctions for the fermions in the presence of these parameters and an external constant magnetic field. We find that these parameters increase the synchrotron radiation emitted by the fermions while also decreasing the traditionally large synchrotron radiation elliptic flow coefficient $v_2$. We apply these results to the quark-gluon plasma, where just such a contribution could provide a solution to the missing direct photons puzzle. We also use our wavefunctions to give a derivation of the chiral magnetic effect.

hep-ph↗
arXiv2025

Polarized electromagnetic radiation by chiral media with time-dependent chiral chemical potential

We investigate photon production from media characterized by a time-dependent chiral chemical potential $\mu_5(t)$. We first consider the chiral anomaly as a small perturbation and show that $\mu_5\to 2\gamma$ process generates non-polarized radiation, as the probabilities of producing right and left-handed photons are equal. In chiral semimetal with a vanishing chiral chemical potential but a finite separation of Weyl nodes, ${\bf \Delta}(t)$, the photon production vanishes at the leading order of perturbation theory. We then employ the method of Bogolyubov transformation to obtain the photon spectrum that sums up all powers of $\mu_5$. Employing the exactly solvable model $\mu_5(t) \propto A+B\tanh(t/\tau)$, we demonstrate that the spectrum exhibits strong circular polarization, whose direction is determined by the sign of $\mu_5$. The spectrum contains resonances associated with the instability of the electromagnetic field in chiral media. We discuss potential phenomenological applications of these findings.

hep-ph↗
arXiv2025

Chiral Cherenkov radiation in the presence of a time-dependent chiral chemical potential

The photon production process $f\to f+\gamma$ in the presence of a time-dependent chiral chemical potential $\mu_5$ is studied. The validity of the adiabatic approximation is demonstrated in the ultra-relativistic limit. Analytical expressions for the photon spectrum are derived for two models of the chiral magnetic conductivity $b_0\propto \mu_5$: (i) $b_0(t)= A_1+B_1\tanh(t/\tau)$ and (ii) $b_0(t)= A_2(t/\tau)/(1+t^2/\tau^2)$. It is known that for constant $b_0$, photon emission may exhibit a resonance for one photon polarization depending on the sign of $b_0$. It is shown that in model (i), up to two resonances may occur, depending on the sign of the asymptotic values $b_0(\infty)$ and $b_0(-\infty)$. No resonances are observed in model (ii). Numerical calculations are performed using parameters relevant to quark-gluon plasma, and the universality of the results is discussed.

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↗
arXiv2025

Time-evolution of parity-odd cascades in homogeneous Abelian and non-Abelian media with chiral imbalance

We study radiation by a fast particle in a medium with a finite chiral chemical potential. The medium's anomalous response encompasses the chiral magnetic effect, enabling novel chiral Cherenkov and pair production processes. The kinematics of the corresponding cascades is fundamentally different from conventional cascades. Notably, it is not dominated by the strong ordering of momenta. Employing the effective Chern-Simons extensions of QED and QCD to incorporate the chiral magnetic effect, we derive and solve the evolution equations describing the cascades in a chiral medium, presuming that the anomalous contributions are dominant.

hep-ph↗
arXiv2025

Rotational stability of magnetic field in rotating quark-gluon plasma

Relaxation of the magnetic field in rigidly rotating quark-gluon plasma is studied. It is shown that the infrared modes satisfying $k < |m|\Omega$ and $k< |m\pm 1|\Omega$, where integer $m$ is the projection of the orbital angular momentum along the rotating axis and $\Omega$ is the angular velocity, are unstable. The instability onset time and the magnetic field growth rate are computed for a standard initial profile of the magnetic field. Given the present phenomenological values of $\Omega$ and electrical conductivity $\sigma$ the instability is not expected to be a significant factor in the field's time evolution.

hep-ph↗
arXiv2024

Sokolov--Ternov effect in rotating systems

We study electromagnetic radiation by electrically charged fermions embedded in a rotating medium in an external magnetic field. We compute the dependence of the radiation intensity on the angular velocity $\Omega$ of the rotating medium for fermion polarizations along and opposite the magnetic field direction in intense subcritical fields. The polarization dependence of the photon radiation results in the Sokolov--Ternov effect -- the radiative polarization of fermions. We study the dependence of the degree of polarziation on $\Omega$. We found that rotation significantly changes the degree of polarization. We show that the rotating quark-gluon plasma acquires a finite magnetic moment that exhibits complex dependence on $\Omega$.

hep-ph↗
arXiv2024

Chiral effects on radiation and energy loss in quark-gluon plasma

The emergent axion excitations in the quark-gluon plasma are generated by the sphaleron transitions. Their interactions with the photon and gluon fields are governed by the axion electro- and chromodynamics respectively. We discuss the effect of the emergent axion on the photon production and energy loss in the quark-gluon plasma. In particular, we review the Chiral Cherenkov effect, and the impact of the chiral anomaly on bremsstrahlung.

hep-ph↗
arXiv2024

Synchrotron radiation of vector bosons at relativistic colliders

Magnetic fields produced in collisions of electrically charged particles at relativistic energies are strong enough to affect the dynamics of the strong interactions. In particular, it induces radiation of vector bosons by relativistic fermions. To develop deeper insight into this problem, I calculate the corresponding spectrum in constant magnetic field and analyze its angular distribution and mass dependence. As an application, I consider synchrotron radiation of virtual photon by the quark-gluon plasma.

hep-ph↗
arXiv2024

Color Chiral Cherenkov radiation and energy loss in quark-gluon plasma

We introduce and investigate the Color Chiral Cherenkov effect which consists in radiation of the circularly polarized gluons by a fast color charge moving with constant velocity in the presence of the Chiral Magnetic current. We derive the transition rates for all gluon polarizations. We compute the contribution of the Color Chiral Cherenkov effect to the parton energy loss in the quark-gluon plasma.

hep-ph↗
arXiv2024

Causal fermion states in magnetic field in a relativistic rotating frame and electromagnetic radiation by a rapidly rotating charge

We consider the Dirac field uniformly rotating with angular velocity $\Omega$ and also subject to the constant magnetic field $B$ directed along the rotation axis. The causal states are constrained to the interior of the light cylinder of radius $c/\Omega$. When this radius is smaller than the system size, as in the quark-gluon plasma, the effect of the boundary on the fermion spectrum is critical. We derive the fermion spectrum and study its properties. We compute the intensity of the electromagnetic radiation emitted due to transitions between the fermion states. We study its dependence on energy and angular momentum for different values of the angular velocity and the magnetic field. Rotation has enormous impact on the electromagnetic radiation by the quark-gluon plasma with or without the magnetic field.

hep-ph↗
arXiv2023

Electromagnetic radiation at extreme angular velocity

We consider a system rotating at extremely high angular velocity, so that its matter is found mostly at the light-cylinder. We posit that it can be described by quantum fields confined to the two-dimensional cylindrical surface rotating about its symmetry axis. We apply this model to study the electromagnetic radiation. In particular, we compute the photon spectrum emitted by the quark-gluon plasma.

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↗