Heidelberg 2015 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 75: Heavy Ion Collisions and QCD Phases 12

HK 75.5: Talk

Friday, March 27, 2015, 15:45–16:00, T/SR25

Identified charged hadron p_T spectra as a function of multiplicity in pp collisions at √s = 7 TeV with ALICE — •Benjamin Heß for the ALICE collaboration — Universität Tübingen, Phyiskalisches Institut I, Auf der Morgenstelle 14, 72076 Tübingen

The intriguing observation of hadron correlations in high-multiplicity pp collisions at the LHC [1] suggests possible collective effects occurring in “central” pp collisions. The multiplicity dependence of particle ratios is very sensitivity to various final-state effects like hadronisation, colour reconnection, and collective flow that are implemented in hadronic Monte Carlo models.

The ALICE detector provides excellent tracking and particle identification. Charged pions, kaons and (anti-)protons are identified using the TPC specific energy loss (dE/dx) in the momentum range up to about 20 GeV/c. In this talk, the measurements of identified charged hadron spectra (π/K/p) as a function of multiplicity in pp collisions at √s = 7 TeV are presented. The multiplicity dependence of the yield ratios is compared to p-Pb and Pb-Pb collisions. In this context, different multiplicity estimators are discussed.

[1] CMS Collaboration, “Observation of Long-Range Near-Side Angular Correlations in Proton-Proton Collisions at the LHC”, JHEP 1009 (2010) 091, arXiv:1009.4122.