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Apr 10 – 12, 2019
Denver, CO
US/Mountain timezone

Measurement of long-range correlations in Z-boson tagged pp collisions

Apr 12, 2019, 9:45 AM
Director's Row J (Denver, CO)

Director's Row J

Denver, CO

Sheraton Denver Downtown Hotel, 1550 Court Pl. lobby level of the Plaza building
invited talk Small Systems


Dr Soumya Mohapatra (Columbia University)


Measurements of two-particle correlations in relative azimuthal angle and pesudorapidity have shown striking similarities between results obtained in pp, and in p+A and A+A collision systems. In pp collisions, unlike in the p+A and A+A systems, the strength of the correlations quantified by the anisotropy parameter $v_2$ does not show any dependence on the charged-particle multiplicity. Recent theoretical models suggest that this can be due to lack of correlation between the charged-particle multiplicity and the impact parameter of the pp collision. An independent handle on the impact parameter can be obtained by requiring the presence of a hard-scattering process in the collision. This talk presents the first measurement of two-particle correlations in pp collisions with a Z boson identified via its dimuon decay channel. The analysis uses ATLAS data recorded under nominal pp luminosities, and a procedure to correct for contribution of the tracks coming from pileup vertices is used. The anisotropy parameter $v_2$ measured in Z-tagged events is compared to the $v_2$ measured in minimum-bias collisions.

Primary author

Dr Soumya Mohapatra (Columbia University)

Presentation materials