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Explore quarkonium types (J/ψ and Υ), suppression in p+A collisions, cold nuclear effects, and more. Understand the impacts on identifying hot medium temperatures and investigating properties of QGP.
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Nuclear effects on quarkonium production in p+nucleus collisions Dhruv Dixit
Outline • Quarkonium: • What are they? • What they reveal? • Types: J/ψ (Charmonium)and Υ (Bottomonium) • Suppression in P+A • Cold Nuclear Effects D. Dixit 290E S17
Qurakonium • Meson made of quark-anti quark pair • Two possibilities: • Charmonium (c c-bar) • J/ψ and ψ (2S) • Bottomonium (b b-bar) • Υ D. Dixit 290E S17
Why look at quarkonium? • Bottomonium • 3 states Y(1S), Y(2S), Y (3S) • The binding energy of the Υ (2S) state (∼540 MeV) is about half that of the Υ (1S) state (∼1.1 GeV); the Υ (3S) is still more weakly bound at ∼200 MeV. • Help identify the temperature of the hot medium • Charmonium • Longer lifetime than bottomonium • Good hard probes to explore properties of QGP due to a longer duration of strong interaction • Both can also be used to look at saturation physics D. Dixit 290E S17
Cold Nuclear Matter Effects • Gluon Shadowing • Nuclear absorption • The probablitity that the quark anti-quark pair will make it through the medium with out • Calculated using the absorption cross-section of the D. Dixit 290E S17
Suppression factor D. Dixit 290E S17
Suppression due to medium effects J/ψ suppression seen in a RpA vs eta plot. Dotted curve presents nuclear suppression of J/Ψ as function of rapidity in pA collisions calculated with the analytic formula Eq. (12). Dashed curve presents more accurate numerical calculations with the full dipole cross section Eq. (2). Solid curve is corrected for gluon shadowing. Data are for d-Au collisions at √ s = 200 GeV [10]. https://arxiv.org/pdf/1008.4272.pdf D. Dixit 290E S17
Suppression due to medium effects Nuclear suppression of Υ production as function of rapidity in pA collisions at √ s = 200 GeV (upper curve, gold) and √ s = 5.5 TeV (two bottom curves, lead). The bottom dashed curve includes only the effects of ¯bb dipole break-up and high twist shadowing of beauty production, solid curve is corrected for gluon shadowing. https://arxiv.org/pdf/1008.4272.pdf D. Dixit 290E S17
Suppression due to medium effects The cross-section yield for the upsilon in d-Au and pp. As we can see, the yield is less and the upsilon mesons are suppressed. D. Dixit 290E S17
Cold nuclear effect comparison to PbPb Cold Nuclear Matter effects on J/ψ production with extrinsic PT at √sNN = 2.76 TeV at the LHC. Nuclear Physics A 855 (2011) 327–330 D. Dixit 290E S17
Sources • https://arxiv.org/pdf/1204.4609.pdf • https://arxiv.org/pdf/0912.4498.pdf • https://arxiv.org/pdf/1305.1724.pdf • https://arxiv.org/pdf/1310.2230.pdf • https://arxiv.org/pdf/1008.4272.pdf • Physics Letters B 735 (2014) 127–137 • Nuclear Physics A 855 (2011) 327–330 • Nuclear Physics A 956 (2016) 689–692 D. Dixit 290E S17