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arXiv · 2102.02890

On the interpretation of $\Lambda$ spin polarization measurements

Wojciech Florkowski·Radoslaw Ryblewski
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Abstract

The physics interpretation of the recent measurements of the spin polarization of $\Lambda$ hyperons produced in relativistic heavy-ion collisions is discussed. We suggest that the polarization measured in the $\Lambda$ rest frame should be projected along the direction of the total angular momentum that is first transformed to the same frame, and only then averaged over $\Lambda$'s with different momenta in the center-of-mass frame. While this procedure does not affect the current measurements done in a broad transverse-momentum range, it may become important (represent a correction of about 10\%) for the most energetic hyperons under study (with transverse momenta reaching 4-5 GeV/c). The proposed treatment is generally more appropriate for relativistic $\Lambda$'s. Throughout the paper, we deliver explicit expressions for various boosts, rotations, and transformations of angular distributions, which may help to compare model predictions with the experimental results.

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Wojciech Florkowski, Radoslaw Ryblewski. 2021-02-04. On the interpretation of $\Lambda$ spin polarization measurements. https://doi.org/10.1103/physrevc.106.024905

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