Flow analysis with cumulants: Direct calculations

By A. Bilandzic, R. Snellings, S. Voloshin. 2010

429 citations recorded by the source corpus.

Anisotropic flow measurements in heavy-ion collisions provide important information on the properties of hot and dense matter. These measurements are based on analysis of azimuthal correlations and might be biased by contributions from correlations that are not related to the initial geometry, so-called nonflow. To improve anisotropic flow measurements, advanced methods based on multiparticle correlations (cumulants) have been developed to suppress nonflow contribution. These multiparticle correlations can be calculated by looping over all possible multiplets, however, this quickly becomes prohibitively CPU intensive. Therefore, the most used technique for cumulant calculations is based on generating functions. This method involves approximations, and has its own biases, which complicates the interpretation of the results. In this paper we present a new exact method for direct calculations of multiparticle cumulants using moments of the flow vectors.

Subfields: Aerospace Engineering, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/e71c86d81e82bb4f10902c29c5340014a0efb21a

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Citations in the corpus

Robust Independent Validation of Experiment and Theory: Rivet version 3 (2019, methodology): “In Rivet we have implemented the Generic Framework formalism [54, 55], plus a number of convenient shorthands.”
Evidence for collectivity in pp collisions at the LHC (2016, methodology): “The Fourier harmonics vn that characterize the global azimuthal behavior are related to the multi-particle cumulants [54] using vn{4} = 4 √−cn{4}, vn{6} = 6 √ 1 4 cn{6}.”
Heavy-flavour and quarkonium production in the LHC era: from proton–proton to heavy-ion collisions (2015, methodology): “The second coefficient, v2 or elliptic flow, which is the dominant component of the anisotropy in non-central nucleus–nucleus collisions, is measured using these three methods: event plane (EP) [498], scalar product (SP) [499] and multi-particle cumulants [500].”
Elliptic flow of electrons from heavy-flavour hadron decays at mid-rapidity in Pb-Pb collisions at √sNN=2.76 TeV (2016, methodology): “#» In the case of the scalar product method, unit track weights w i are used in the construction of the Q 2 vector, and possible non-uniformities in the detector are corrected with the non-uniform acceptance correction described in [65].”
Long-range angular correlations of pi, K and p in p-Pb collisions at root s(NN)=5.02 TeV (2013, background): “Further, genuine four-particle correlations utilizing cumulants [28] lead to non-zero v 2 coefﬁcients that are somewhat smaller than those extracted from two-particle correlations, and smaller than those in Pb–Pb collisions at the same midrapidity multiplicity.”