$J/\psi$ polarization in p+p collisions at $\sqrt{s}$ = 200 GeV in STAR - IN2P3 - Institut national de physique nucléaire et de physique des particules Access content directly
Journal Articles Physics Letters B Year : 2013

$J/\psi$ polarization in p+p collisions at $\sqrt{s}$ = 200 GeV in STAR

L. Adamczyk
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We report on a polarization measurement of inclusive $J/\psi$ mesons in the di-electron decay channel at mid-rapidity at 2 $< p_T <$ 6 GeV/c in p+p collisions at $\sqrt{s}$ = 200 GeV. Data were taken with the STAR detector at RHIC. The $J/\psi$ polarization measurement should help to distinguish between the different models of the $J/\psi$ production mechanism since they predict different $p_T$ dependences of the $J/\psi$ polarization. In this analysis, $J/\psi$ polarization is studied in the helicity frame. The polarization parameter $\lambda_{\theta}$ measured at RHIC becomes smaller towards high $p_T$, indicating more longitudinal $J/\psi$ polarization as $p_T$ increases. The result is compared with predictions of presently available models.

Dates and versions

in2p3-00913294 , version 1 (03-12-2013)



L. Adamczyk, W. Borowski, S. Kabana. $J/\psi$ polarization in p+p collisions at $\sqrt{s}$ = 200 GeV in STAR. Physics Letters B, 2013, 739, pp.180-188. ⟨10.1016/j.physletb.2014.10.049⟩. ⟨in2p3-00913294⟩
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