Observable signatures of initial state momentum anisotropies in nuclear collisions
Résumé
We show that the correlation between the elliptic momentum anisotropy v2 and the average transverse momentum [pT] at fixed multiplicity in small system nuclear collisions carries information on the origin of the observed momentum anisotropy. A calculation using a hybrid IP-Glasma+music+UrQMD model that includes contributions from final state response to the initial geometry as well as initial state momentum anisotropies of the color glass condensate predicts a characteristic sign change of the correlator ρ^(v22,[pT]) as a function of charged particle multiplicity in p+Au and d+Au collisions at s=200 GeV, and p+Pb collisions at s=5.02 TeV. This sign change is absent in calculations without initial state momentum anisotropies. The model further predicts a qualitative difference between the centrality dependence of ρ^(v22,[pT]) in Au+Au collisions at s=200 GeV and Pb+Pb collisions at s=5.02 TeV, with only the latter showing a sign change in peripheral events. Predictions for O+O collisions at different collision energy show a similar behavior. Experimental observation of these distinct qualitative features of ρ^(v22,[pT]) in small and large systems would constitute strong evidence for the presence and importance of initial state momentum anisotropies predicted by the color glass condensate effective theory.
Mots clés
Nuclear Physics
momentum: anisotropy
charged particle: multiplicity
nucleus nucleus: scattering
quantum molecular dynamics: relativistic
model: hybrid
initial state
color glass condensate
transverse momentum
hydrodynamics
correlation
glasma
numerical calculations
200 GeV-cms/nucleon
5020 GeV-cms/nucleon