# Measurement of the polarization of the $\Upsilon(1S)$ and $\Upsilon(2S)$ states in $p\bar{p}$ collisions at $\sqrt{s}=$1.96 TeV

Abstract : We present a study of the polarization of the $\Upsilon(1S)$ and $\Upsilon(2S)$ states using a $1.3$ fb$^{-1}$ data sample collected by the D0 experiment in 2002--2006 during Run II of the Fermilab Tevatron Collider. We measure the polarization parameter $\alpha=(\sigma_{T}-2\sigma_{L})/(\sigma_{T}+2\sigma_{L})$, where $\sigma_{T}$ and $\sigma_{L}$ are the transversely and longitudinally polarized components of the production cross section, as a function of the transverse momentum ($p_{T}^{\Upsilon}$) for the $\Upsilon(1S)$ and $\Upsilon(2S)$. Significant $p_{T}^{\Upsilon}$-dependent longitudinal polarization is observed for the $\Upsilon(1S)$. A comparison with theoretical models is presented.
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http://hal.in2p3.fr/in2p3-00274807
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Submitted on : Monday, April 21, 2008 - 3:25:44 PM
Last modification on : Friday, December 4, 2020 - 1:22:02 PM

### Citation

V.M. Abazov, B. Abbott, M. Abolins, B.S. Acharya, M. Adams, et al.. Measurement of the polarization of the $\Upsilon(1S)$ and $\Upsilon(2S)$ states in $p\bar{p}$ collisions at $\sqrt{s}=$1.96 TeV. Physical Review Letters, American Physical Society, 2008, 101, pp.182004. ⟨10.1103/PhysRevLett.101.182004⟩. ⟨in2p3-00274807⟩

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