Study of the dynamics of soft interactions with two-particle angular correlations at ATLAS

Oropeza Barrera, Cristina (2012) Study of the dynamics of soft interactions with two-particle angular correlations at ATLAS. PhD thesis, University of Glasgow.

Abstract

Measurements of inclusive two-particle angular correlations in proton-proton collisions at centre-of-mass energies of 900 GeV and 7 TeV are presented. The events were collected with the ATLAS detector at the LHC, using a single-arm minimum-bias trigger, during 2009 and 2010. Correlations are measured for charged particles in the kinematic range defined by pT > 100 MeV and |eta| < 2.5. In total, integrated luminosities of 7 1/ub and 190 1/ub are analysed for 900 GeV and 7 TeV data, respectively. At 900 GeV only events with a charged particle multiplicity n_ch >= 2 are analysed whereas at 7 TeV, a second phase-space region of n_ch >= 20, with a suppressed contribution from diffractive events, is also explored.

Data is corrected using a novel approach in which the detector effects are applied repeatedly to the observable distribution and then extrapolated to a detector effect of zero.

A complex structure in pseudorapidity and azimuth is observed for the correlation function at both collision energies. Projections of the two-dimensional correlation distributions are compared to the Monte Carlo generators Pythia 8 and Herwig++ as well as the AMBT2B, DW and Perugia 2011 tunes of Pythia 6. The strength of the correlations seen in the data is not reproduced by any of the models.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Particle Physics, Minimum Bias, Monte Carlo Generators, Soft QCD, Two-Particle Correlations, HBOM Method, ATLAS
• Subjects: Q Science > QC Physics
• Colleges/Schools: College of Science and Engineering > School of Physics and Astronomy
• Supervisor's Name: Buttar, Dr. Craig M.
• Date of Award: 2012
• Depositing User: Cristina Oropeza Barrera
• Unique ID: glathesis:2012-3185
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 13 Feb 2012
• Last Modified: 10 Dec 2012 14:04
• URI: https://theses.gla.ac.uk/id/eprint/3185