The measurement of two-particle angular correlations is a powerful tool to study jet quenching in a p(T) region inaccessible by direct jet identification. In these measurements pseudorapidity (Delta(eta)) and azimuthal (Delta phi) differences are used to extract the shape of the near-side peak formed by particles associated with a higher p(T) trigger particle (1 < p(T,trig) < 8 GeV/c). A combined fit of the near-side peak and long-range correlations is applied to the data allowing the extraction of the centrality evolution of the peak shape in Pb-Pb collisions at root s(NN) = 2.76 TeV. A significant broadening of the peak in the Delta(eta) direction at low p(T) is found from peripheral to central collisions, which vanishes above 4 GeV/c, while in the Delta(phi) direction the peak is almost independent of centrality. For the 10% most central collisions and 1 < p(T,assoc) < 2 GeV/c, 1 < p(T,trig) < 3 GeV/c a novel feature is observed: a depletion develops around the center of the peak. The results are compared to pp collisions at the same center of mass energy and AMPT model simulations. The comparison to the investigated models suggests that the broadening and the development of the depletion is connected to the strength of radial and longitudinal flow.

Anomalous Evolution of the Near-Side Jet Peak Shape in Pb-Pb Collisions at root S-NN=2.76 TeV

Audurier, B.;Casula, E. A. R.;Cicalo, C.;De Falco, A.;Fionda, F. M.;Siddhanta, S.;Usai, G. L.;
2017

Abstract

The measurement of two-particle angular correlations is a powerful tool to study jet quenching in a p(T) region inaccessible by direct jet identification. In these measurements pseudorapidity (Delta(eta)) and azimuthal (Delta phi) differences are used to extract the shape of the near-side peak formed by particles associated with a higher p(T) trigger particle (1 < p(T,trig) < 8 GeV/c). A combined fit of the near-side peak and long-range correlations is applied to the data allowing the extraction of the centrality evolution of the peak shape in Pb-Pb collisions at root s(NN) = 2.76 TeV. A significant broadening of the peak in the Delta(eta) direction at low p(T) is found from peripheral to central collisions, which vanishes above 4 GeV/c, while in the Delta(phi) direction the peak is almost independent of centrality. For the 10% most central collisions and 1 < p(T,assoc) < 2 GeV/c, 1 < p(T,trig) < 3 GeV/c a novel feature is observed: a depletion develops around the center of the peak. The results are compared to pp collisions at the same center of mass energy and AMPT model simulations. The comparison to the investigated models suggests that the broadening and the development of the depletion is connected to the strength of radial and longitudinal flow.
lead-lead collisions; root-s(nn)=2.76 tev; atlas detector; centrality; dependence; angular-correlations; transverse-momentum; suppression; pp
File in questo prodotto:
File Dimensione Formato  
PhysRevLett.119.102301.pdf

accesso aperto

Tipologia: versione editoriale
Dimensione 693.9 kB
Formato Adobe PDF
693.9 kB Adobe PDF Visualizza/Apri

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: http://hdl.handle.net/11584/228775
Citazioni
  • ???jsp.display-item.citation.pmc??? 1
  • Scopus 12
  • ???jsp.display-item.citation.isi??? 10
social impact