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arXiv · 1604.04597

Ultra-relativistic nuclear collisions: where the spectators flow?

Sergei A. Voloshin·Takafumi Niida
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Abstract

In high energy heavy ion collisions, the directed flow of particles is conventionally measured with respect to that of the projectile spectators, which is defined as positive $x$ direction. But it is not known if the spectators deflect in the "outward" direction or "inward" -- toward the center line of the collision. In this Letter we discuss how the measurements of the directed flow at mid-rapidity, especially in asymmetric collision such as Cu+Au, can be used to answer this question. We show that the existing data strongly favor the case that the spectators, in the ultrarelativistic collisions, on average deflect outwards.

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Sergei A. Voloshin, Takafumi Niida. 2016-04-21. Ultra-relativistic nuclear collisions: where the spectators flow?. https://doi.org/10.1103/physrevc.94.021901

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