PoS - Proceedings of Science
Volume 456 - 25th International Symposium on Spin Physics (SPIN2023) - 3D Structure of the Nucleon: TMDs
Measurement of $\Lambda^0$-hyperon spin-spin correlations in $p+p$ collisions at $\sqrt{s} = 200$ and $510\,\textrm{GeV}$ by the STAR experiment
J. Vanek*  on behalf of the STAR collaboration
Full text: pdf
Published on: July 30, 2024
Abstract
About 50 years ago, it was discovered that $\Lambda^0$ hyperons are produced polarized in collisions of unpolarized protons on beryllium. Despite enormous experimental and theoretical efforts, the origin of this polarization remains inconclusive to date. The $\Lambda^0$ polarization has also been observed in various collision systems, from $e^+$+$e^-$ to heavy-ion collisions. A recently proposed technique for the investigation of the $\Lambda^0$ hyperon polarization is a measurement of $\Lambda^0\bar{\Lambda}^0$, $\Lambda^0\Lambda^0$, and $\bar{\Lambda}^0\bar{\Lambda}^0$ spin-spin correlations. This technique is expected to help understand if the polarization is generated at early stages of the collisions, e.g. from initial state parton spin correlation, or if it is a final state effect originating from hadronization.

In these proceedings, we present a status of the first measurement utilizing this new experimental method in $p$+$p$ collisions at $\sqrt{s} = 200\,\textrm{GeV}$ by the STAR experiment. The $\Lambda^0$ and $\bar{\Lambda}^0$ candidates are reconstructed at mid-rapidity ($|y| < 1$) and in two transverse momentum ($p_\mathrm{T}$) bins which allows us to extract the $\Lambda^0$-hyperon spin-spin correlations for various $p_\mathrm{T}$ combinations of hyperons in $\Lambda^0\bar{\Lambda}^0$, $\Lambda^0\Lambda^0$, and $\bar{\Lambda}^0\bar{\Lambda}^0$ pairs. This measurement will provide new insight into $\Lambda^0$ hyperon spin polarization in $p$+$p$ collisions at RHIC energies.
DOI: https://doi.org/10.22323/1.456.0046
How to cite

Metadata are provided both in "article" format (very similar to INSPIRE) as this helps creating very compact bibliographies which can be beneficial to authors and readers, and in "proceeding" format which is more detailed and complete.

Open Access
Creative Commons LicenseCopyright owned by the author(s) under the term of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.