# Differential probes of medium-induced energy loss

Abstract : Results from the PHENIX experiment of measurements of high- $p_{\rm T}$ particle production presented at the Hard Probes 2004 Conference are summarized. This paper focuses on a sub-set of the measurements presented at the conference, namely the suppression of $\pi^0$ production at moderate to high $p_{\rm T}$ as a function of angle with respect to the collision reaction plane, $\Delta\phi$ , for different collision centralities. The data are presented in the form of nuclear modification factor as a function of angle with respect to the reaction plane, $R_{AA} (\Delta \phi)$ . The data are analyzed using empirical estimates of the medium-induced energy loss obtained from the $R_{AA} (\Delta \phi)$ values. A geometric analysis is performed with the goal of understanding the simultaneous dependence of RAA on $\Delta\phi$ and centrality. We find that the centrality and $\Delta\phi$ dependence of the $\pi^0$ suppression can be made approximately consistent using an admittedly over-simplistic description of the geometry of the jet propagation in the medium but only if the energy loss is effectively reduced for short parton path lengths in the medium. We find that with a more "canonical" treatment of the quenching geometry, the $\pi^0$ suppression varies more rapidly with $\Delta\phi$ than would be expected from the centrality dependence of the suppression.
Document type :
Journal articles
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http://hal.in2p3.fr/in2p3-00024988
Contributor : Dominique Girod Connect in order to contact the contributor
Submitted on : Wednesday, November 2, 2005 - 3:11:42 PM
Last modification on : Tuesday, April 20, 2021 - 12:00:09 PM

### Citation

S.S. Adler, S. Afanasiev, C. Aidala, N.N. Ajitanand, Y. Akiba, et al.. Differential probes of medium-induced energy loss. European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2005, 43, pp.271-280. ⟨10.1140/epjc/s2005-02333-7⟩. ⟨in2p3-00024988⟩

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