Heidelberg 2015 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 75: Heavy Ion Collisions and QCD Phases 12
HK 75.4: Vortrag
Freitag, 27. März 2015, 15:30–15:45, T/SR25
The relevance of multi-parton interactions for event-by-event mean pT fluctuations in pp collisions — •Stefan Heckel for the ALICE collaboration — Goethe-Universität Frankfurt, Institut für Kernphysik, Max-von-Laue-Str. 1, 60438 Frankfurt am Main
Event-by-event mean transverse momentum fluctuations in pp collisions have recently been measured by ALICE at the LHC [1]. High collision energies as reached at the LHC enable the occurence of multiple hard scatterings in a single pp collision, due to the large number of partons within the ultra-relativistically moving particles. High-multiplicity events in pp collisions at LHC energies are believed to be driven by such multi-parton interactions (MPIs).
We present an analysis of the influence of MPIs on event-by-event mean transverse momentum fluctuations in pp collisions at √s = 7 TeV, which has been performed with Monte Carlo simulations using PYTHIA8. The results for those fluctuations are presented as a function of the charged-particle multiplicity density and dependent on the number of multi-parton interactions. In addition, the simulations have been performed with and without the color reconnection mechanism. The inclusive results taking into account all numbers of MPIs are very similar in both cases, but for discrete numbers of MPIs they show significant and interesting differences. Finally, the results are compared to the measurements by ALICE.
[1] ALICE Collaboration, B. Abelev et al., Eur. Phys. J. C 74 (2014) 3077. arXiv:1407.5530 [nucl-ex]