# EPS HEP 2013 Stockholm

17-24 July 2013
KTH and Stockholm University Campus
Europe/Stockholm timezone

## Spectator charge splitting of directed flow in heavy ion collisions

18 Jul 2013, 10:08
20m
E2 (KTH Campus)

### E2

#### KTH Campus

Talk presentation Ultrarelativistic Heavy Ions

### Speaker

Antoni Szczurek (Institute of Nuclear Physics)

### Description

We estimate the electromagnetic effect of the spectator charge on azimuthal anisotropies observed in heavy ion collisions. For peripheral Pb+Pb reactions at the top energy of the CERN Super Proton Synchrotron, $\sqrt{s_{NN}}=17.3$ GeV, we predict this effect to bring very large distortions to the observed directed flow, $v_1$, of positive and negative pions emitted close to beam rapidity. The overall magnitude of this effect is comparable to values of $v_1$ reported by the WA98 experiment. We argue that also at lower rapidities, the spectator induced electromagnetic effect may result in the splitting of values of $v_1$ observed for positive and negative pions. Such a splitting is visible also in the data reported by the STAR Collaboration from the RHIC Beam Energy Scan. Both effects are sensitive to the space-time scenario assumed for pion emission. Therefore, the electromagnetic splitting brings new information on the collision dynamics. The presentation will be based on our recent preprint [1]. 1) A. Rybicki and A. Szczurek, arXiv:1303.7354, submitted to Phys. Rev. {\bf C}.

### Primary author

Antoni Szczurek (Institute of Nuclear Physics)

### Co-author

Dr Andrzej Rybicki (Institute of Nuclear Physics, Krakow)

 Slides