Measurement of the ${\rm Y}$ polarizations in $pp$ collisions at $\sqrt{s}$=7 and 8TeV

Abstract

The polarization of the ${\rm Y}(1S)$, ${\rm Y}(2S)$ and ${\rm Y}(3S)$mesons, produced in $pp$ collisions at centre-of-mass energies $\sqrt{s}$=7 and 8TeV, is measured using data samples collected by the LHCb experiment, corresponding to integrated luminosities of 1 and 2fb${}^{-1}$, respectively. The measurements are performed in three polarization frames, using ${\rm Y}\to {\mu }^{+}{\mu }^{-}$ decays in the kinematic region of the transverse momentum $p_T({\rm Y})<30GeV/c$, and rapidity $2.2<y({\rm Y})<4.5$. No large polarization is observed.

61 page, 15 figures, 28 tables. All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2017-028.html

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