QM 2011 - XXII International Conference on Ultrarelativistic Nucleus-Nucleus Collisions

Transverse sphericity in minimum bias proton-proton collisions at $\sqrt{s}$ = 0.9 and 7 TeV with ALICE at the LHC

Not scheduled

1m

Théâtre National (Centre Bonlieu)

Board: 102

Poster Correlations and fluctuations

Speaker

Antonio Ortiz Velasquez (Universidad Nac. Autonoma de Mexico (UNAM))

Description

A study of the linearized sphericity in minimum bias proton-proton collisions at $\sqrt{s}$ = 0.9 and 7 TeV with the ALICE detector at the LHC is presented. The observable was measured in the plane perpendicular to the beam direction and using primary charged tracks in $|\eta|\leq0.8$. The average sphericity as a function of multiplicity is reported for events with different hardness (``soft'' and ``hard'') defined by a cut on the transverse momentum of the leading particle. In addition to those studies the average transverse momentum versus multiplicity was measured for different event classes. Data are compared with PYTHIA6 (tunes: ATLAS-CSC and PERUGIA-0), PYTHIA8 and PHOJET. The behavior of the linearized sphericity and of the mean $p_{T}$ with multiplicity indicates that the current event generators tend to ``build up'' multiplicity by generating more jets while on the contrary the data indicate that at high multiplicity the events tend to be more isotropic and the mean $p_{T}$ smaller.