Improved measurement of the longitudinal spin transfer to $Λ$ and $\bar Λ$ hyperons in polarized proton-proton collisions at $\sqrt s$ = 200 GeV



Adam, J, Adamczyk, L, Adams, JR, Adkins, JK, Agakishiev, G, Aggarwal, MM, Ahammed, Z, Alekseev, I, Anderson, DM, Aoyama, R
et al (show 346 more authors) Improved measurement of the longitudinal spin transfer to $Λ$ and $\bar Λ$ hyperons in polarized proton-proton collisions at $\sqrt s$ = 200 GeV. Phys. Rev. D, 98. 112009 - ?.

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Abstract

The longitudinal spin transfer $D_{LL}$ to $\Lambda$ and $\bar{\Lambda}$ hyperons produced in high-energy polarized proton--proton collisions is expected to be sensitive to the helicity distribution functions of strange quarks and anti-quarks of the proton, and to longitudinally polarized fragmentation functions. We report an improved measurement of $D_{LL}$ from data obtained at a center-of-mass energy of $\sqrt{s}$ = 200 GeV with the STAR detector at RHIC. The data have an approximately twelve times larger figure-of-merit than prior results and cover $|\eta|<$ 1.2 in pseudo-rapidity with transverse momenta $p_T$ up to 6 GeV/c. In the forward scattering hemisphere at largest $p_T$, the longitudinal spin transfer is found to be $D_{LL}$ = -0.036 $\pm$ 0.048 (stat) $\pm$ 0.013(sys) for $\Lambda$ hyperons and $D_{LL}$ = 0.032 $\pm$ 0.043\,(stat) $\pm$ 0.013\,(sys) for $\bar{\Lambda}$ anti-hyperons. The dependences on $\eta$ and $p_T$ are presented and compared with model evaluations.

Item Type: Article
Additional Information: 8 pages, 4 figures
Uncontrolled Keywords: hep-ex, hep-ex
Depositing User: Symplectic Admin
Date Deposited: 07 May 2019 09:37
Last Modified: 12 Nov 2019 17:11
DOI: 10.1103/PhysRevD.98.112009
Open Access URL: https://doi.org/10.1103/PhysRevD.98.112009
Related URLs:
URI: http://livrepository.liverpool.ac.uk/id/eprint/3040028
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