Measurement longtidudinal flow corrleations in PbPb collisions from ATLAS at LHC
by
huo peng(State University of New York (US))
→
US/Eastern
Small Seminar Room (Universe)
Small Seminar Room
Universe
Description
Longitudinal dynamics has recently become a topic of great interest in the study of ultra-relativistic heavy ion collisions. Measurement of the longitudinal fluctuations of the flow harmonic coefficients and event-plane angles can provide a more complete picture of space-time evolution of the hot, dense medium formed in heavy ion collisions. Longitudinal flow decorrelations can be modeled with two contributions: magnitude fluctuations and event plane twist. However, existing observables do not separate these two effects. In this analysis, a new 4-particle correlator is used to separate the event-plane twist from magnitude fluctuations in 2.76 and 5.02 Pb+Pb collisions. Results show both effects have a linear dependence on pseudorapidity separation for , and show a small but measurable variation with collision energy. The correlation of of different order are also expected to have longitudinal fluctuations due to the non-linear mixing effects between lower and higher order flow harmonics. First measurement of such non-linear mode-mixing effects as a function of pseudorapidity is also presented. These result will help to constrain initial conditions along longitudinal direction and also help understand the longitudinal evolution of the fireball.