Charge-dependent directed flow in asymmetric nuclear collisions

Abstract

The directed flow of identified hadrons is studied within the parton-hadron-string-dynamics (PHSD) approach for the asymmetric system Cu+Au in non-central collisions at $\sqrt{s_{NN}}$ = 200 GeV. It is emphasized that due to the difference in the number of protons of the colliding nuclei an electric field emerges which is directed from the heavy to the light nucleus. This strong electric field is only present for about 0.25 fm/c at $\sqrt{s_{NN}}$ = 200 GeV and leads to a splitting of the directed flow $v_1$ for particles with the same mass but opposite electric charges in case of an early presence of charged quarks and antiquarks. The microscopic calculations of the directed flow for ${\pi }^{\pm },K^{\pm },p$ and $\bar{p}$ are carried out in the PHSD by taking into account the electromagnetic field induced by the spectators as well as its influence on the hadronic and partonic quasiparticle trajectories. It is shown that the splitting of the directed flow as a function of pseudorapidity $\eta$ and in particular as a function of the transverse momentum $p_t$ provides a direct access to the electromagnetic response of the very early (nonequilibrium) phase of relativistic heavy-ion collisions and allows to shed light on the presence (and number) of electric charges in this phase.

8 pages, 12 figures

References in corpus (10)

• Triangularity and Dipole Asymmetry in Heavy Ion Collisions
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• From Kadanoff-Baym dynamics to off-shell parton transport
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• Dilepton production in proton-proton and Pb+Pb collisions at sqrt(s_NN)=2.76 TeV
• The Spectator Electromagnetic Effect on Charged Pion Spectra in Peripheral Ultrarelativistic Heavy-Ion Collisions
• Event-by-event viscous hydrodynamics for Cu-Au collisions at 200GeV
• Anisotropic flow in Cu+Au collisions at $\sqrt{s_{NN}}=200$ GeV

Cited by in corpus (4)

• Electric Fields and Chiral Magnetic Effect in Cu + Au Collisions
• Impact of the initial size of spatial fluctuations on the collective flow in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV
• Possible observables for the chiral electric separation effect in Cu + Au collisions
• Charge splitting of directed flow and charge-dependent effects in pion spectra in heavy ion collisions