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Peter Christiansen Profile

Peter Christiansen

Professor

Peter Christiansen Profile

Event-shape and multiplicity dependence of freeze-out radii in pp collisions at √s = 7 TeV

Author

  • S Acharya
  • Jonatan Adolfsson
  • Peter Christiansen
  • Martin Ljunggren
  • Adrian Nassirpour
  • Anders Oskarsson
  • Tuva Richert
  • David Silvermyr
  • Evert Stenlund
  • Vytautas Vislavicius
  • G Zinovjev
Show all

Summary, in English

Two-particle correlations in high-energy collision experiments enable the extraction of particle source radii by using the Bose-Einstein enhancement of pion production at low relative momentum q ∝ 1/R. It was previously observed that in pp collisions at s = 7TeV the average pair transverse momentum kT range of such analyses is limited due to large background correlations which were attributed to mini-jet phenomena. To investigate this further, an event-shape dependent analysis of Bose-Einstein correlations for pion pairs is performed in this work. By categorizing the events by their transverse sphericity ST into spherical (ST > 0:7) and jet-like (ST < 0:3) events a method was developed that allows for the determination of source radii for much larger values of kT for the first time. Spherical events demonstrate little or no background correlations while jet-like events are dominated by them. This observation agrees with the hypothesis of a mini-jet origin of the non-femtoscopic background correlations and gives new insight into the physics interpretation of the kT dependence of the radii. The emission source size in spherical events shows a substantially diminished kT dependence, while jet-like events show indications of a negative trend with respect to kT in the highest multiplicity events. Regarding the emission source shape, the correlation functions for both event sphericity classes show good agreement with an exponential shape, rather than a Gaussian one. [Figure not available: see fulltext.]. © 2019, The Author(s).

Department/s

  • Particle and nuclear physics
  • eSSENCE: The e-Science Collaboration

Publishing year

2019

Language

English

Publication/Series

Journal of High Energy Physics

Volume

2019

Issue

9

Document type

Journal article

Publisher

Springer

Topic

  • Subatomic Physics

Keywords

  • Heavy Ion Experiments
  • Particle correlations and fluctuations

Status

Published

ISBN/ISSN/Other

  • ISSN: 1029-8479