Proton, deuteron and triton flow measurements in Au+Au collisions at \(\sqrt{s_{_{{\text {NN}}}}}= 2.4\) GeV

Abstract

High-precision measurements of flow coefficients \[v_{n}\] ( \[n = 1 - 4\] ) for protons, deuterons and tritons relative to the first-order spectator plane have been performed in Au+Au collisions at \[\sqrt{s_{_{{\text {NN}}}}}= 2.4\]  GeV with the High-Acceptance Di-Electron Spectrometer (HADES) at the SIS18/GSI. Flow coefficients are studied as a function of transverse momentum \[p_{{\text {t}}}\] and rapidity \[y_{{\text {cm}}}\] over a large region of phase-space and for several classes of collision centrality. A clear mass hierarchy, as expected by relativistic hydrodynamics, is found for the slope of \[v_{1}\] , \[d v_{1}/d y^{\prime }|_{y^{\prime } = 0}\] where \[y^{\prime }\] is the scaled rapidity, and for \[v_{2}\] at mid-rapidity. Scaling with the number of nucleons is observed for the \[p_{{\text {t}}}\]  dependence of \[v_{2}\] and \[v_{4}\] at mid-rapidity, which is indicative for nuclear coalescence as the main process responsible for light nuclei formation. \[v_{2}\] is found to scale with the initial eccentricity \[\langle \epsilon _{2} \rangle \] , while \[v_{4}\] scales with \[\langle \epsilon _{2} \rangle ^{2}\] and \[\langle \epsilon _{4} \rangle \] . The multi-differential high-precision data on \[v_{1}\] , \[v_{2}\] , \[v_{3}\] , and \[v_{4}\] provides important constraints on the equation-of-state of compressed baryonic matter.