Quark Matter 2019 - the XXVIIIth International Conference on Ultra-relativistic Nucleus-Nucleus Collisions

Electromagnetically induced flow in heavy ion collisions

5 Nov 2019, 15:00

20m

HongKong Room (Wanda Reign Wuhan Hotel)

Oral Presentation New theoretical developments Parallel Session - New theoretical developments I

Speaker

Dmitri Kharzeev

Description

I will discuss the charge-dependent flow induced by magnetic and electric fields in heavy ion
collisions. We simulate the evolution of the expanding cooling droplet of strongly coupled plasma
hydrodynamically, using the iEBE-VISHNU framework, and add the magnetic and electric fields as
well as the electric currents they generate in a perturbative fashion. We confirm the previously
reported effect of the electromagnetically induced currents, that is a charge-odd directed flow
$\mathrm{\Delta }{v}_1$ that is odd in rapidity, noting that it is induced by magnetic fields (a la Faraday and Lorentz)
and by electric fields (the Coulomb field from the charged spectators). In addition, we find a
charge-odd $\mathrm{\Delta }{v}_3$ that is also odd in rapidity and that has a similar physical origin. We furthermore
show that the electric field produced by the net charge density of the plasma drives rapidity-even
charge-dependent contributions to the radial flow $⟨p_T⟩$ and the elliptic flow $\mathrm{\Delta }{v}_2$. Although their
magnitudes are comparable to the charge-odd $\mathrm{\Delta }{v}_1$ and $\mathrm{\Delta }{v}_3$, they have a different physical origin, namely the Coulomb forces within the plasma. Recent ALICE and STAR measurements confirm these effects but exhibit an opposite sign and bigger magnitude. I will discuss possible ingredients missing in the theory that would possibly resolve this apparent mismatch.

Presentation materials

QM2019_Kharzeev.pdf