Azimuthal anisotropies of charged particles with high transverse momentum in Pb plus Pb collisions at √sNN=5.02 TeV with the ATLAS detector

AbstraktAbstract

A measurement is presented of elliptic (v(2)) and triangular (v(3)) azimuthal anisotropy coefficients for charged particles produced in Pb+Pb collisions at root s(NN) = 5.02 TeV using a dataset corresponding to an integrated luminosity of 0.44 nb(-1) collected with the ATLAS detector at the LHC in 2018. The values of v(2) and v(3) are measured for charged particles over a wide range of transverse momentum (p(T)), 1-400 GeV, and Pb+Pb collision centrality, 0-60%, using the scalar-product and multiparticle cumulant methods. These methods are sensitive to event-by-event fluctuations and nonflow effects in the measurements of azimuthal anisotropies. Positive values of v(2) are observed up to a p(T) of approximately 100 GeV from both methods across all centrality intervals. Positive values of v(3) are observed up to approximately 25 GeV using both methods, though the application of the three-subevent technique to the multiparticle cumulant method leads to significant changes at the highest p(T). At high p(T) (p(T) (sic) 10 GeV), charged particles are dominantly from jet fragmentation. These jets, and hence the measurements presented here, are sensitive to the path-length dependence of parton energy loss in the quark-gluon plasma produced in Pb+Pb collisions.

A measurement is presented of elliptic (v(2)) and triangular (v(3)) azimuthal anisotropy coefficients for charged particles produced in Pb+Pb collisions at root s(NN) = 5.02 TeV using a dataset corresponding to an integrated luminosity of 0.44 nb(-1) collected with the ATLAS detector at the LHC in 2018. The values of v(2) and v(3) are measured for charged particles over a wide range of transverse momentum (p(T)), 1-400 GeV, and Pb+Pb collision centrality, 0-60%, using the scalar-product and multiparticle cumulant methods. These methods are sensitive to event-by-event fluctuations and nonflow effects in the measurements of azimuthal anisotropies. Positive values of v(2) are observed up to a p(T) of approximately 100 GeV from both methods across all centrality intervals. Positive values of v(3) are observed up to approximately 25 GeV using both methods, though the application of the three-subevent technique to the multiparticle cumulant method leads to significant changes at the highest p(T). At high p(T) (p(T) (sic) 10 GeV), charged particles are dominantly from jet fragmentation. These jets, and hence the measurements presented here, are sensitive to the path-length dependence of parton energy loss in the quark-gluon plasma produced in Pb+Pb collisions.