Speaker
Description
Spin correlations between hyperons provide a novel probe of spin-dependent particle production and hadronization in quantum chromodynamics (QCD). Using the high-statistics data collected by the CMS experiment, we present the first measurements of spin correlations for $\Lambda\Lambda$, $\Lambda\bar{\Lambda}$, and $\bar{\Lambda}\bar{\Lambda}$ pairs in pp collisions at $\sqrt{s}=13$ TeV and pPb collisions at $\sqrt{s_{\mathrm{NN}}}=8.16$ TeV. The correlations are measured as a function of the pair separation, $\Delta R=\sqrt{\Delta\eta^{2}+\Delta\phi^{2}}$. At small $\Delta R$, $\Lambda\Lambda$ and $\bar{\Lambda}\bar{\Lambda}$ pairs exhibit negative short-range spin correlations. No significant positive short-range spin correlation is observed for $\Lambda\bar{\Lambda}$ pairs, in qualitative contrast to previous observations at lower collision energies. These measurements provide new constraints on models of hyperon-pair production and on the origin of spin correlations in hadronic collisions.
