Studying the interplay of strong and electromagnetic forces in heavy-ion collisions with NICA

Abstract.In this paper we demonstrate that radiation patterns could cause flow-like behaviour without any reference to hydrodynamic description. For that purpose we use a statistical ensemble of radiating dipoles, motivated by the investigation of the equivalent photon yield produced by decelerating charges. For the elliptic asymmetry factor, v 2, we find a reasonable agreement with experimental data.Hydrodynamical simulations are widely used to describe the early time evolution of proton-nucleus and heavy-ion collisions, see refs. [1][2][3][4][5][6][7][8][9][10][11] and the references therein. However, the fact that hydrodynamics has a strong predictive power does not imply that it is the only option to explain collective phenomena in such systems. There have been recent efforts to reproduce the flow patterns observed in RHIC and LHC using color scintillating antennas radiating gluons [12,13]. Other authors utilized phenomenological models of color-electric dipoles in order to account for angular correlations in high-energy processes [14][15][16]. It is an ongoing debate though, whether a simple effective model, lacking hydrodynamics, could catch the flow-like behaviour or not. Unfortunately, it is rather complicated to explain the collective properties using microscopical models as a starting point.In this letter, our goal is to demonstrate that the radiation originating from a dipole set-up is, in principle, able to match quantitatively the elliptic asymmetry factor v 2 , measured in heavy-ion experiments. To do so, we discuss the yield of massless particles produced by a decelerating point-like charge. Then we compute the flow coefficient v 2 of a dipole composed of two, parallel displaced counterdecelerating charges. Motivated by the formula in eq. (6), we fit various experimental data. Finally, we conclude our analysis discussing several open issues and their relevance for further, more realistic description. Radiation produced by decelerating sourcesAccording to electrodynamics, an accelerating point charge radiates. One can reinterpret this phenomenon a

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“…The directed flow of charged pions could be a result of a spectator induced splitting, as it is demonstrated in refs. [37,38].…”

Section: I) Strong Electromagnetic (Em) Fieldsmentioning

confidence: 99%