HAL : in2p3-00274807, version 1
 arXiv : 0804.2799
 Physical Review Letters 101 (2008) 182004
 Measurement of the polarization of the $\Upsilon(1S)$ and $\Upsilon(2S)$ states in $p\bar{p}$ collisions at $\sqrt{s}=$1.96 TeV
 D0 Collaboration(s)
 (2008)
 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.
 Thème(s) : Physique/Physique des Hautes Energies - Expérience
 Lien vers le texte intégral : http://fr.arXiv.org/abs/0804.2799
 in2p3-00274807, version 1 http://hal.in2p3.fr/in2p3-00274807 oai:hal.in2p3.fr:in2p3-00274807 Contributeur : Danielle Cristofol <> Soumis le : Lundi 21 Avril 2008, 15:25:44 Dernière modification le : Lundi 3 Novembre 2008, 08:07:52