CMS-BPH-13-003

CMS-BPH-13-003 ; CERN-PH-EP-2013-140
Measurement of the prompt $\mathrm{J}/\psi$ and $\psi \mathrm{ (2S) }$ polarizations in pp collisions at $\sqrt{s}$ = 7 TeV
CMS Collaboration
23 July 2013
Phys. Lett. B 727 (2013) 381-402
Abstract: The polarizations of prompt $\mathrm{J}/\psi$ and $\psi \mathrm{ (2S) }$ mesons are measured in proton-proton collisions at $\sqrt{s}$ = 7 TeV, using a dimuon data sample collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 4.9 inverse femtobarns. The prompt $\mathrm{J}/\psi$ and $\psi \mathrm{ (2S) }$ polarization parameters $\lambda_{ \theta }$ , $\lambda_{ phi }$ , $\lambda_{ \theta, phi }$ , as well as the frame-invariant quantity $\tilde{ \lambda }$ , are measured from the dimuon decay angular distributions in three different polarization frames. The $\mathrm{J}/\psi$ results are obtained in the transverse momentum range 14 $< p_{ \mathrm{ T } } <$ 70 GeV, in the rapidity intervals $\|y\| <$ 0.6 and 0.6 $< \|y\| <$ 1.2. The corresponding $\psi \mathrm{ (2S) }$ results cover 14 $< p_{ \mathrm{ T } } <$ 50 GeV and include a third rapidity bin, 1.2 $< \|y\| <$ 1.5. No evidence of large transverse or longitudinal polarizations is seen in these kinematic regions, which extend much beyond those previously explored.
Links: e-print arXiv:1307.6070 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; Public twiki page ; HepData record ; CADI line (restricted) ;

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