Exploring gluon tomography with polarization dependent diffractive J/$ψ$ production

Abstract

We study azimuthal asymmetries in diffractive J/ψ production in ultraperipheral heavy-ion collisions at RHIC and LHC energies using the color glass condensate effective theory. Our calculation successfully describes azimuthal averaged J/ψ production cross section measured by STAR and ALICE. We further predict very large cos 2φ and cos 4φ azimuthal asymmetries for diffractive J/ψ production both in UPCs at RHIC and LHC energies and in eA collisions at EIC energy. These novel polarization dependent observables may provide complementary information for constraining gluon transverse spatial distribution inside large nuclei. As compared to all previous analysis of diffractive J/ψ production, the essential new elements integrated in our theoretical calculations are: the double-slit interference effect, the linear polarization of coherent photons, and the final state soft photon radiation effect.

Azimuthal decorrelation for photon induced dijet production in ultra-peripheral collisions of heavy ions

“…Besides, UPCs involve two-photon fusions and photonuclear interactions, which provide an opportunity to study the quasi-real photons emitted by one of the colliding nuclei and probe the nuclear parton distribution functions (PDFs). Typical photonuclear processes [6][7][8][9][10][11][12][13][14][15] involve the photoproduction of vector mesons via photon-gluon fusions, which is a clean probe to study the gluon distributions inside the energetic nucleus [16][17][18][19][20][21][22][23][24][25][26]. Typical two-photon interactions involve dilepton productions [27][28][29][30][31][32][33] or diphoton productions from light-by-light scatterings [34].…”