Azimuthally differential pion femtoscopy in Pb-Pb collisions at 2.76 TeV with ALICE at the LHC

Abstract

Femtoscopy of non-central heavy ion collisions provides access to information on the geometry of the effective pion-emitting source. In particular, the source shape can be studied by measuring femtoscopic radii as a function of the pion emission angle relative to the collision symmetry planes. We present the results of azimuthally differential femtoscopy of Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV at the LHC relative to the second harmonic event plane. We observe a clear oscillation of the extracted radii as a function of the emission angle. We find that $R_{side}$ and $R_{out}$ oscillate out of phase for all centralities and pion transverse momenta. The relative amplitude of $R_{side}$ oscillation decreases in more central collisions, but remains positive, which indicates that the source remains out-of-plane extended qualitatively similar to what was observed at RHIC energies. We compare our results to existing hydrodynamical and transport model calculations.

4 pages, 4 figures, Proceedings for Quark Matter 2014, Darmstadt, Germany, May 19-24, 2014

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• Azimuthally-sensitive femtoscopy from RHIC to LHC in hydrodynamics with statistical hadronization
• Evolution of pion HBT radii from RHIC to LHC -- Predictions from ideal hydrodynamics
• Shape analysis of strongly-interacting systems: the heavy ion case
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Cited by in corpus (5)

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• Higher-order anisotropies in the Blast-Wave Model - disentangling flow and density field anisotropies
• Overview of ALICE Results at Quark Matter 2014
• Dynamical vs geometric anisotropy in relativistic heavy-ion collisions: which one prevails?
• Higher order anisotropies in the Buda-Lund model: Disentangling flow and density field anisotropies