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Register a new userTransverse Single Spin Asymmetry in $J/psi$ Production
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We estimate transverse single spin asymmetry (TSSA) in electroproduction of $J/psi$ for J-Lab and EIC energies. We present estimates of TSSAs in $J/psi$ production within generalized parton model (GPM) using recent parametrizations of gluon Sivers function (GSF) and compare the results obtained using color singlet model (CSM) with those obtained using color evaporation model (CEM) of quarkonium production.
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We report on a recent investigation of the single spin asymmetry (SSA) in low virtuality electroproduction of $J/psi$ in color evaporation model. We show that this can be used as a probe for the still unknown gluon Sivers function.
We calculate the production cross-section and the transverse single-spin asymmetry for pion in $p^{uparrow}+pto pi^0 + X$. Our computation is based on existence of the instanton induced effective quark-gluon and quark-gluon-pion interactions with a strong spin dependency. In this framework we calculate the cross section without using fragmentation functions. We compare predictions of the model with data from RHIC. Our numerical results, based on the instanton liquid model for QCD vacuum, are in agreement with unpolarized cross section data. The asymmetry grows with the transverse momentum of pion $k_t$ in accordance with experimental observations. It reach value $sim 10%$ but at higher $k_t$ than experiment shows.
The abundant production of lepton pairs via $J/Psi$ creation at COMPASS, $pi ^pm , p^uparrow to J/Psi , X to ell^+ ell^- X$, allows a measurement of the transverse Single Spin Asymmetry generated by the Sivers effect. The crucial issue of the sign change of the Sivers function in lepton pair production, with respect to Semi Inclusive Deep Inelastic Scattering processes, can be solved. Predictions for the expected magnitude of the Single Spin Asymmetry, which turns out to be large, are given.
We study the single-transverse spin asymmetry for open charm production in the semi-inclusive lepton-hadron deep inelastic scattering. We calculate the asymmetry in terms of the QCD collinear factorization approach for $D$ mesons at high enough $P_{hperp}$, and find that the asymmetry is proportional to the twist-three tri-gluon correlation function in the proton. With a simple model for the tri-gluon correlation function, we estimate the asymmetry for both COMPASS and eRHIC kinematics, and discuss the possibilities of extracting the tri-gluon correlation function in these experiments.
We report the first measurement of transverse single-spin asymmetries in $J/psi$ production from transversely polarized $p+p$ collisions at $sqrt{s} = 200$ GeV with data taken by the PHENIX experiment in 2006 and 2008. The measurement was performed over the rapidity ranges $1.2 < |y| < 2.2$ and $ |y| < 0.35$ for transverse momenta up to 6 GeV/$c$. $J/psi$ production at RHIC is dominated by processes involving initial-state gluons, and transverse single-spin asymmetries of the $J/psi$ can provide access to gluon dynamics within the nucleon. Such asymmetries may also shed light on the long-standing question in QCD of the $J/psi$ production mechanism. Asymmetries were obtained as a function of $J/psi$ transverse momentum and Feynman-$x$, with a value of $-0.086 pm 0.026^{rm stat} pm 0.003^{rm syst}$ in the forward region. This result suggests possible nonzero trigluon correlation functions in transversely polarized protons and, if well defined in this reaction, a nonzero gluon Sivers distribution function.
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