Linearly polarized gluons in charmonium and bottomonium production in color octet model

We study the possibility to probe the unpolarized and linearly polarized transverse momentum- dependent gluon distributions in unpolarized pp collision in charmonium and bottomonium produc- tion, employing non-relativistic QCD (NRQCD) based color octet model within transverse momentum dependent (TMD) factorization framework. The transverse momentum (p T ) and rapidity distributions of J/{\psi} and {\Upsilon}(1S) at LHCb, RHIC and AFTER energies are estimated. Significant modulations in transverse momentum spectrum of quarkonium in the low p T region is obtained when contributions of linearly polarized gluons inside an unpolarized proton are taken into account. The results of quarko- nium production in color octet model and color evaporation model are compared.Comment: Replaced with the revised version, to appear in PR

J/ψJ/\psi Production in Polarized and Unpolarized epep Collision and Sivers and cos⁡2ϕ\cos2\phi Asymmetries

We calculate the Sivers and $\cos2\phi$ azimuthal asymmetries in $J/\psi$ production in polarized and unpolarized semi-inclusive $ep$ collision respectively, using the formalism based on transverse momentum dependent parton distributions (TMDs). Non-relativistic QCD based color octet model is employed for calculating the $J/\psi$ production rate. The Sivers asymmetry in this process directly probes the gluon Sivers function. The estimated Sivers asymmetry at $z=1$ is negative which is in good agreement with COMPASS data. We also investigate the effect of TMD evolution on the Sivers asymmetry. The $\cos2\phi$ asymmetry is sizable and probes the linearly polarized gluon distribution in an unpolarized proton.Comment: 29 pages, 11 figures. Details of calculation adde

Azimuthal asymmetries in DD-meson and jet production at the EIC

We study the azimuthal asymmetries in back-to-back leptoproduction of $D$-meson and jet to probe the gluon TMDs in an unpolarized and transversely polarized electron-proton collision at the kinematics of EIC. We give predictions for unpolarized cross-sections within the TMD factorization framework. In $D$-meson and jet formation, the only leading order contribution comes from the photon gluon fusion process. We give numerical estimates of the upper bound on the azimuthal asymmetries with the saturation of positivity bounds; also, we present the asymmetries using a Gaussian parameterization of TMDs. We obtain sizable asymmetries in the kinematics that will be accessible at EIC.Comment: 19 pages, 13 figures, the version to be published in PR

J/ψJ/\psi polarization in large-PTP_T semi-inclusive deep-inelastic scattering at the EIC

We present a detailed phenomenological study of $J/\psi$ polarization in semi-inclusive deep inelastic scattering processes, focusing on the kinematics accessible at the future Electron-Ion Collider. We show theoretical estimates for the standard polarization parameters for different frames usually adopted in the literature, in the large $P_T$ region, namely $P_T\gg \Lambda_\text{QCD}$, where collinear factorization is expected to hold. We adopt both the Color Singlet Model and the Nonrelativistic QCD approach, paying special attention to the role of different sets of Long Distance Matrix Elements. Finally we present a preliminary analysis of some frame independent polarization invariants.Comment: 14 pages, 7 figure

Process dependence of the gluon Sivers function in p↑p→J/ψ+Xp^\uparrow p \to J/\psi + X within a TMD approach in NRQCD

We consider the transverse single-spin asymmetry (SSA) for $J/\psi$ production in $p^\uparrow p \to J/\psi + X$ within a TMD approach in non-relativistic QCD. Extending a previous study [1], we employ here the color-gauge invariant generalized parton model (CGI-GPM), in which spin and intrinsic transverse momentum effects are taken into account, together with leading-order initial- and final-state interactions (ISIs and FSIs). We find that, even when the heavy-quark pair is produced in a color-octet state, ISIs and FSIs lead to a nonvanishing SSA, allowing, in principle, to test the process dependence of the gluon Sivers function (GSF). We show that of the two independent contributions, due to the so-called $f$- and $d$-type GSFs, appearing in the CGI-GPM, the $d$-type one turns out to be dynamically suppressed. Therefore, as already found adopting the Color-Singlet Model approach for the $J/\psi$ formation [2], only the $f$-type GSF could play a role in phenomenology. A comparison with the corresponding results obtained in the generalized parton model, without the inclusion of ISIs and FSIs, is also carried out.Comment: 19 pages, 12 figures (18 plots), 8 table

Sivers asymmetry in inelastic J/ψJ/ψ leptoproduction at the EIC

We study the Sivers asymmetry in inelastic J/\psiJ/ψ leptoproduction, ep^\uparrow \to e+ J/\psi+Xep↑→e+J/ψ+X, within a transverse momentum dependent scheme, the so-called generalized parton model (GPM). The effects of final-state interactions are properly taken into account by employing the color-gauge invariant GPM (CGI-GPM). For the J/\psiJ/ψ formation the non-relativistic QCD (NRQCD) framework is adopted. Predictions for unpolarized cross sections and maximized Sivers asymmetries at EIC energies are given