We present the first azimuthally differential measurements of the pion source size relative to the second harmonic event plane in Pb-Pb collisions at a center-of-mass energy per nucleon-nucleon pair of root(NN)-N-s = 2.76 TeV. The measurements have been performed in the centrality range 0%-50% and for pion pair transverse momenta 0.2 < k(T) < 0.7 GeV/c. We find that the R-side and R-out radii, which characterize the pion source size in the directions perpendicular and parallel to the pion transverse momentum, oscillate out of phase, similar to what was observed at the Relativistic Heavy Ion Collider. The final-state source eccentricity, estimated via R-side oscillations, is found to be significantly smaller than the initial-state source eccentricity, but remains positive-indicating that even after a stronger expansion in the in-plane direction, the pion source at the freeze-out is still elongated in the out-of-plane direction. The 3 + 1D hydrodynamic calculations are in qualitative agreement with observed centrality and transverse momentum R-side oscillations, but systematically underestimate the oscillation magnitude.

Azimuthally Differential Pion Femtoscopy in Pb-Pb Collisions at sNN =2.76 TeV

BOCA, GIANLUIGI;COSTANZA, SUSANNA;ROTONDI, ALBERTO;
2017-01-01

Abstract

We present the first azimuthally differential measurements of the pion source size relative to the second harmonic event plane in Pb-Pb collisions at a center-of-mass energy per nucleon-nucleon pair of root(NN)-N-s = 2.76 TeV. The measurements have been performed in the centrality range 0%-50% and for pion pair transverse momenta 0.2 < k(T) < 0.7 GeV/c. We find that the R-side and R-out radii, which characterize the pion source size in the directions perpendicular and parallel to the pion transverse momentum, oscillate out of phase, similar to what was observed at the Relativistic Heavy Ion Collider. The final-state source eccentricity, estimated via R-side oscillations, is found to be significantly smaller than the initial-state source eccentricity, but remains positive-indicating that even after a stronger expansion in the in-plane direction, the pion source at the freeze-out is still elongated in the out-of-plane direction. The 3 + 1D hydrodynamic calculations are in qualitative agreement with observed centrality and transverse momentum R-side oscillations, but systematically underestimate the oscillation magnitude.
2017
Applied Physics/Condensed Matter/Materials Science encompasses the resources of three related disciplines: Applied Physics, Condensed Matter Physics, and Materials Science. The applied physics resources are concerned with the applications of topics in condensed matter as well as optics, vacuum science, lasers, electronics, cryogenics, magnets and magnetism, acoustical physics and mechanics. The condensed matter physics resources are concerned with the study of the structure and the thermal, mechanical, electrical, magnetic and optical properties of condensed matter. They include superconductivity, surfaces, interfaces, thin films, dielectrics, ferroelectrics and semiconductors. The materials science resources are concerned with the physics and chemistry of materials and include ceramics, composites, alloys, metals and metallurgy, nanotechnology, nuclear materials, adhesion and adhesives. Resources dealing with polymeric materials are listed in the Organic Chemistry/Polymer Science category.
Esperti anonimi
Inglese
Internazionale
STAMPA
118
22
222301
Physics and Astronomy (all)
http://harvest.aps.org/bagit/articles/10.1103/PhysRevLett.118.222301/apsxml
1028
info:eu-repo/semantics/article
262
Adamovã¡, D.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahmad, S.; Ahn, S. U.; Aiola, S.; Akindinov, A.; Alam, S. N...espandi
1 Contributo su Rivista::1.1 Articolo in rivista
none
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11571/1197548
Citazioni
  • ???jsp.display-item.citation.pmc??? 0
  • Scopus 16
  • ???jsp.display-item.citation.isi??? 13
social impact