Measurement of the transverse polarization of Λ and Λ¯ hyperons produced in proton–proton collisions at √s=7 TeV using the ATLAS detector

Aad, G. and Abbott, B. and Abdallah, J. and Khalek, S. A. and Abdinov, O. and Krasznahorkay, Attila and Nagai, Yoshikazu and Pásztor, Gabriella and Tóth, József (2015) Measurement of the transverse polarization of Λ and Λ¯ hyperons produced in proton–proton collisions at √s=7 TeV using the ATLAS detector. PHYSICAL REVIEW D, 91 (3). ISSN 2470-0010

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Abstract

The transverse polarization of Λ and Λ hyperons produced in proton–proton collisions at a center-of-mass energy ¯ of 7 TeV is measured. The analysis uses 760 µb −1 of minimum bias data collected by the ATLAS detector at the LHC in the year 2010. The measured transverse polarization averaged over Feynman xF from 5 × 10−5 to 0.01 and transverse momentum pT from 0.8 to 15 GeV is −0.010 ± 0.005(stat) ± 0.004(syst) for Λ and 0.002 ± 0.006(stat) ± 0.004(syst) for Λ. It is also measured as a function of ¯ xF and pT, but no significant dependence on these variables is observed. Prior to this measurement, the polarization was measured at fixedtarget experiments with center-of-mass energies up to about 40 GeV. The ATLAS results are compatible with the extrapolation of a fit from previous measurements to the xF range covered by this measurement.

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