PoS - Proceedings of Science
Volume 390 - 40th International Conference on High Energy physics (ICHEP2020) - Parallel: Heavy Ions
Spin alignment measurements of vector mesons with ALICE at the LHC
B. Mohanty* on behalf of the ALICE collaboration
*corresponding author
Full text: Not available
Abstract
We present the measurements related to the spin alignment of $K^{*}$ and $\phi$ vector mesons at mid-rapidity for Pb--Pb collisions at $\sqrt{s_{\rm nn}}$ = 2.76 TeV using the ALICE detector at the LHC. The second diagonal spin density matrix element ($\rho_{00}$) is measured from the angular distribution of the decay daughters of the vector meson in the decay rest frame, with respect to the event plane and the production plane. The $\rho_{00}$ values are found to be less than 1/3 at low $p_{\rm T}$ ($<$ 2 GeV/$c$) for both vector mesons. The observed deviations from 1/3 are maximal for mid-central collisions at a level of 3$\sigma$ for $K^{*}$ and 2$\sigma$ for $\phi$ mesons. As a control measurement the $\rho_{00}$ values were found to be consistent with 1/3, i.e., no significant spin alignment, for pp collisions with respect to the production plane. The results are qualitatively consistent with the expectation from a model that attributes the spin alignment to a polarization of quarks in the presence of large initial angular momentum and a subsequent hadronization by the process of recombination.
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.