Signatures of $\alpha$ clustering in ultra-relativistic collisions with light nuclei

TL;DR

This paper investigates how alpha clustering in light nuclei affects initial spatial correlations and observable flow signatures in ultra-relativistic nuclear collisions, providing specific predictions for experimental detection.

Contribution

It introduces a novel approach linking alpha clustering in light nuclei to measurable flow patterns and multiplicity distributions in high-energy collisions.

Findings

Elliptic flow is sensitive to clustering in ${}^{7,9}$Be.

Triangular flow is sensitive to clustering in ${}^{12}$C and ${}^{16}$O.

Clusterization affects multiplicity distributions depending on polarization orientation.

Abstract

We explore possible observable signatures of $\alpha$ clustering of light nuclei in ultra-relativistic nuclear collisions involving ${}^{7,9}$Be, ${}^{12}$C, and ${}^{16}$O. The clustering leads to specific spatial correlations of the nucleon distributions in the ground state, which are manifest in the earliest stage of the ultra-high energy reaction. The formed initial state of the fireball is sensitive to these correlations, and the effect influences, after the collective evolution of the system, the hadron production in the final stage. Specifically, we study effects on the harmonic flow in collisions of light clustered nuclei with a heavy target (${}^{208}$Pb), showing that measures of the elliptic flow are sensitive to clusterization in ${}^{7,9}$Be, whereas triangular flow is sensitive to clusterization in ${}^{12}$C and ${}^{16}$O. Specific predictions are made for model collisions at the CERN SPS energies. In another exploratory development we also examine the proton-beryllium collisions, where the $3/2^-$ ground state of ${}^{7,9}$Be nucleus is polarized by an external magnetic field. Clusterization leads to multiplicity distributions of participant nucleons which depend on the orientation of the polarization with respect to the collision axis, as well as on the magnetic number of the state. The obtained effects on multiplicities reach a factor of a few for collisions with a large number of participant nucleons.