First Observation of Deuteron- Λ Correlations at RHIC

Precise experimental information on hyperon-nucleon interactions is scarce but of paramount importance to our understanding of the inner structure of compact stars. In this Letter, we report the first experimental results of correlation functions between deuterons (d) and Λ hyperons in Au+Au collisions at sqrt[s_{NN}]=3.0 GeV measured by the STAR experiment at the Relativistic Heavy Ion Collider. A clear enhancement at small relative momenta has been observed in the correlation function. Through a Bayesian inference analysis, the source size parameters as a function of collision centrality and the spin-dependent strong interaction parameters (scattering length f_{0} and effective range d_{0}) are extracted using the Lednický-Lyuboshitz formalism. The derived doublet spin state parameters (f_{0}, d_{0}) lead to a novel method to precisely determine Λ separation energy for the weakly bounded hypertriton _{Λ}^{3}H.