# Nucleus Nucleus 2015

Jun 21 – 26, 2015
Dipartimento di Fisica ed Astronomia, Università di Catania
Europe/Rome timezone
All the plenary sessions will be transmitted in streaming on the web. From Monday, June 22nd, a link will be available <a href='http://www.streamago.tv/channel/54955/default/iframe/' target='blank'> here </a>

## Understanding the path length dependence of jet quenching in Heavy Ion Collisions from RHIC to LHC

Jun 23, 2015, 4:20 PM
20m
Aula F (Dipartimento di Fisica ed Astronomia, Università di Catania)

### Aula F

#### Dipartimento di Fisica ed Astronomia, Università di Catania

Oral presentation Relativistic Heavy-Ion Collisions

### Speaker

Mr Myunggeun Song (Yonsei University, Seoul, Republic of Korea)

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\begin{document}
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\noindent{\underline{The 12th International Conference on Nucleus-Nucleus Collisions, June 21-26, 2015, Catania, Italy}}

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%{\large \bf Study of $R_{AA}$ as function of Path-length with Flow harmonics and Glauber simulation in AA collisions}
{\large \bf Understanding the path length dependence of jet quenching in Heavy Ion Collisions from RHIC to LHC}
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\underline{Myunggeun Song}$^1$, D.J~Kim$^{2}$
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{\em $^1$ Yonsei University, South Korea} \
{\em $^2$ University of Jyv\"{a}skyl\"{a}, Finland}\
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The centrality dependence of nuclear modification factor($R_{AA}$) carries information about path-length dependent partonic energy loss because mean path-length increases as the centrality increases. However, for a given centrality, inclusive $R_{AA}$ emerges by averaging over different path-lengths which depend on the azimuthal angle w.r.t. the reaction plane assuming elliptical shape of overlapping zone of two colliding nuclei in the transverse plane. In this sense, azimuthal dependence of $R_{AA}$ w.r.t. reaction plane offers to get a tighter constraint on the actual path length traversed by the parton in medium. As the azimuthal angle can be converted into the path-length with Glauber simulation[1] of two colliding nuclei, $R_{AA}$ can be represented as a function of not only $p_T$, but also path-length. By utilizing the existing data from RHIC to LHC[2][3][4], we will show that $R_{AA}$ seems to be aligned with respect to path-length, regardless of centralities in high transverse momentum regions ($p_T > 5GeV/$c) both for RHIC and LHC, and scales like universal function of square of Path-length. These results permit a detailed examination of the influence of geometry in the collision region and of the interplay between collective flow and jet-quenching effects.
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[1] M. L. Miller, et al, Ann.Rev.Nucl.Part.Sci. 57:205-243 (2007) \ \
[2] ALICE, K. Aamodt et al., Phys. Lett. B696, 30 (2011), 1012.1004.\ \
[3] ALICE Collaboration, K. Aamodt et al., Phys. Rev. Lett. 105, 252301 (2010).\ \
[4] CMS Collaboration, Phys. Rev. Lett.87.014902 (2012) \ \

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### Primary authors

Dr Dong Jo Kim (Jyvasklya Univisity) Mr Myunggeun Song (Yonsei University, Seoul, Republic of Korea)

### Co-author

Prof. Juhwan Kang (Yonsei University)

 Slides