Deformation probes for light nuclei in their collisions at relativistic energies

We have investigated the performance of anisotropic flows vₙ², transverse momentum fluctuations δ pT², and their correlations vₙ² δ pT in central collisions at relativistic energies as probes of deformation parameters βₙ of colliding nuclei, if these nuclei are light nuclei with large βₙ and different configurations of α clusters. The effects from higher-order βₙ terms are illustrated by derived relations based on the overlap of two nuclei with uniform density distributions and by dynamic simulations of collisions of heavy nuclei whose density distributions are of a deformed Woods-Saxon (WS) form. While the linear relations between β²ₙ, vₙ², and δ pT² and that between β³ₙ and vₙ² δ pT can be violated for extremely large βₙ, they are mostly valid for realistic values of βₙ, as long as the density distribution of colliding nuclei can be described by a deformed WS form. However, these linear relations are generally not valid with more realistic density distributions of light nuclei with α clusters, and the amount of deviation depends on the detailed α-cluster configurations. Care must be taken when one tries to extract the deformation of light nuclei, and specific probes for α-cluster structures in these nuclei are very much needed.