Quarkonium Production: From JLab to an EIC Sylvester Joosten - PowerPoint PPT Presentation

This work is supported by DOE grant DE-FG02-94ER4084 Quarkonium Production: From JLab to an EIC Sylvester Joosten sylvester.joosten@temple.edu QCD Evolution 2018 (Santa Fe, NM)

Quarkonium in electro- and photo-production l - Strong gluonic interaction between color neutral γ,γ* t J/ψ,Υ objects Minimal quark exchange l + Quarkonium as a probe to p p’ study the gluonic structure of the nucleon S. Joosten 2

Quarkonium photo-production: what do we know? 3 J/ ψ photo-production: 10 J/ ψ 2 10 Direct photo-production 
 10 Cornell ’75, 
 (nb) Cornell '75 SLAC ’75, 
 SLAC '75 1 ψ CERN NA-14 J/ σ CERN NA-14, 
 FNAL E401 − 1 10 FNAL E401, E687 FNAL E687 H1 Combined ( *) γ 2 − 10 ZEUS Combined ( *) γ Electro-production (quasi-real) 
 LHCB '14 (UPC) H1 and ZEUS 3 − 10 2 3 10 10 10 W (GeV) Ultra-peripheral pp collisions 
 3 10 Y(1s) LHCb ’14 2 10 Y(1s) photo-production: 10 (nb) Electro-production (quasi-real) 
 1 Υ σ H1 and ZEUS 1 − 10 Ultra-peripheral pp collisions 
 H1 2000 ( *) γ − 2 10 ZEUS 2009 ( *) γ LHCb ’15 LHCb '15 (UPC) 3 − 10 3 2 10 10 10 W (GeV) S. Joosten 3

Quarkonium photo-production: what do we know? 3 J/ ψ photo-production: 10 J/ ψ 2 10 Well constrained above W > 15 GeV 10 Dominated by t- channel 2-gluon (nb) Cornell '75 exchange SLAC '75 1 ψ CERN NA-14 J/ Almost no data near threshold σ FNAL E401 − 1 10 FNAL E687 H1 Combined ( *) γ l - 2 − 10 ZEUS Combined ( *) γ LHCB '14 (UPC) q γ,γ* 3 − J/ψ,Υ 10 2 3 10 10 10 _ W (GeV) q 3 10 Y(1s) l + 2 10 p p’ 10 (nb) 1 Υ σ Y(1s) photo-production: 1 − 10 H1 2000 ( *) γ Not much available − 2 10 ZEUS 2009 ( *) γ LHCb '15 (UPC) ZEUS measured 62 ± 12 events total! 3 − 10 3 2 10 10 10 W (GeV) S. Joosten 4

Why the threshold region? 3 10 Near Threshold: J/ ψ 2 10 Origin of proton mass , trace 10 anomaly of the QCD energy- (nb) Cornell '75 SLAC '75 momentum tensor. 1 ψ CERN NA-14 J/ σ FNAL E401 Gluonic Van der Waals force , − 1 10 FNAL E687 H1 Combined ( *) γ possible quarkonium-nucleon/ 2 − 10 ZEUS Combined ( *) γ LHCB '14 (UPC) nucleus bound states 3 − 10 2 3 10 10 10 Mechanism for quarkonium W (GeV) 3 10 production Y(1s) 2 10 10 (nb) 1 Υ σ 1 − 10 H1 2000 ( *) γ − 2 10 ZEUS 2009 ( *) γ LHCb '15 (UPC) 3 − 10 3 2 10 10 10 W (GeV) S. Joosten 5

Why the threshold region? 3 10 Near Threshold: J/ ψ 2 10 Origin of proton mass , trace 10 anomaly of the QCD energy- (nb) Cornell '75 SLAC '75 momentum tensor. 1 ψ CERN NA-14 J/ σ FNAL E401 Gluonic Van der Waals force , − 1 10 FNAL E687 H1 Combined ( *) γ possible quarkonium-nucleon/ 2 − 10 ZEUS Combined ( *) γ LHCB '14 (UPC) nucleus bound states 3 − 10 2 3 10 10 10 Mechanism for quarkonium W (GeV) 3 10 production Y(1s) 2 10 10 (nb) 1 J/ ψ program at Jefferson Lab Υ σ 1 − 10 Y(1s) production at an EIC H1 2000 ( *) γ − 2 10 ZEUS 2009 ( *) γ LHCb '15 (UPC) 3 − 10 3 2 10 10 10 W (GeV) S. Joosten 5

Why electro-production at high energies? 3 10 High Energies J/ ψ 2 10 Access Gluon GPD: Full 3D 10 tomography of the gluonic (nb) Cornell '75 SLAC '75 structure of the nucleon 1 ψ CERN NA-14 J/ σ FNAL E401 L-T separation and the Q 2 − 1 10 FNAL E687 H1 Combined ( *) γ dependence of R for 2 − 10 ZEUS Combined ( *) γ LHCB '14 (UPC) quarkonium production 3 − 10 2 3 10 10 10 W (GeV) 3 10 Y(1s) 2 10 10 (nb) 1 Υ σ 1 − 10 H1 2000 ( *) γ − 2 10 ZEUS 2009 ( *) γ LHCb '15 (UPC) 3 − 10 3 2 10 10 10 W (GeV) S. Joosten 6

Why electro-production at high energies? 3 10 High Energies J/ ψ 2 10 Access Gluon GPD: Full 3D 10 tomography of the gluonic (nb) Cornell '75 SLAC '75 structure of the nucleon 1 ψ CERN NA-14 J/ σ FNAL E401 L-T separation and the Q 2 − 1 10 FNAL E687 H1 Combined ( *) γ dependence of R for 2 − 10 ZEUS Combined ( *) γ LHCB '14 (UPC) quarkonium production 3 − 10 2 3 10 10 10 W (GeV) 3 10 Y(1s) 2 10 10 J/ ψ production at an EIC (nb) 1 Y(1s) production at an EIC Υ σ 1 − 10 H1 2000 ( *) γ − 2 10 ZEUS 2009 ( *) γ LHCb '15 (UPC) 3 − 10 3 2 10 10 10 W (GeV) S. Joosten 6

Quarkonium production near threshold

Production mechanism near threshold unknown 2-gluon S.J. Brodsky, et al., Phys.Lett. B498, 23-28 (2001) Same as high energies ( 2-gluon )? S. Joosten 8

Production mechanism near threshold unknown 2-gluon 3-gluon S.J. Brodsky, et al., Phys.Lett. B498, 23-28 (2001) Same as high energies ( 2-gluon )? Maybe 3-gluon exchange dominant? S. Joosten 8

Production mechanism near threshold unknown 2-gluon 3-gluon partonic soft S.J. Brodsky, et al., Phys.Lett. B498, 23-28 (2001) Frankfurt and Strikman., PRD66 (2002), 031502 Or a partonic soft mechanism Same as high energies ( 2-gluon )? (power law 2-gluon form-factor)? Maybe 3-gluon exchange dominant? S. Joosten 8

Production mechanism near threshold unknown 2-gluon 3-gluon partonic soft S.J. Brodsky, et al., Phys.Lett. B498, 23-28 (2001) Frankfurt and Strikman., PRD66 (2002), 031502 Or a partonic soft mechanism Same as high energies ( 2-gluon )? (power law 2-gluon form-factor)? Maybe 3-gluon exchange dominant? Orders of magnitude difference 2-gluon fastest drop-off Drives required luminosity for threshold measurement S. Joosten 8

2-gluon fit near threshold Smallest cross section drives required precision and luminosity Use 2-gluon estimate for experimental projections near threshold 2 10 J/ ψ Y(1s) 3 Cornell '75 H1 2000 ( *) γ 10 SLAC '75 ZEUS 2009 ( *) 10 γ 2 10 SLAC '76 (Unpublished) 2-gluon fit 2-gluon fit 1 10 (nb) (nb) 1 1 − 10 ψ Υ J/ σ σ 1 − 10 2 − 10 2 − 10 3 − 10 3 − 10 4 4 − − 10 10 10 15 20 25 2 10 10 E (GeV) W (GeV) γ S. Joosten 9

Quarkonium-nucleon scattering amplitude γ,γ* J/ψ,Υ J/ψ,Υ J/ψ,Υ VMD p p’ p p’ VMD relates photo-production cross section to quarkonium-nucleon scattering amplitude T ψ p . S. Joosten 10

Quarkonium-nucleon scattering amplitude γ,γ* J/ψ,Υ J/ψ,Υ J/ψ,Υ VMD p p’ p p’ VMD relates photo-production cross section to quarkonium-nucleon scattering amplitude T ψ p . Real part T ψ p dominates near threshold Mostly constrained through dispersive relations, not data. D. Kharzeev, Proc.Int.Sch.Phys.Fermi 130 (1996) 105-131 D. Kharzeev et al. , EPJ-C9 (1999) 459-462 S. Joosten 10

The proton mass is an emergent phenomenon M. S. Bhagwat et al ., Phys. Rev. C 68, 015203 (2003) I. C. Cloet et al ., Prog. Part. Nucl. Phys. 77, 1-69 (2014) Constituent quark mass from DSE and Lattice Low momentum gluons attach to the current quark (DCSB) Gluon field accumulates ~300MeV/constituent quark Even in the chiral limit (mass from nothing)! S. Joosten 11

The proton mass is an emergent phenomenon M. S. Bhagwat et al ., Phys. Rev. C 68, 015203 (2003) I. C. Cloet et al ., Prog. Part. Nucl. Phys. 77, 1-69 (2014) Constituent quark mass from DSE and Lattice Low momentum gluons attach to the current quark (DCSB) Gluon field accumulates ~300MeV/constituent quark Even in the chiral limit (mass from nothing)! The Higgs mechanism is largely irrelevant in “normal” matter! S. Joosten 11

The proton mass : covariant decomposition D. Kharzeev, Proc.Int.Sch.Phys.Fermi 130 (1996) 105-131 Access nucleon mass through trace of energy- momentum tensor (EMT) at zero momentum transfer µ | P i = 2 P µ P µ = 2 M 2 h P | T µ p S. Joosten 12

The proton mass : covariant decomposition D. Kharzeev, Proc.Int.Sch.Phys.Fermi 130 (1996) 105-131 Access nucleon mass through trace of energy- momentum tensor (EMT) at zero momentum transfer µ | P i = 2 P µ P µ = 2 M 2 h P | T µ p At low momentum transfer: heavy quarks decouple ˜ β ( g ) 2 g G 2 + m q (1 + γ m ) ¯ X T µ µ = ψ q ψ q q = u,d,s Trace Anomaly Light Quark Mass S. Joosten 12

The proton mass : covariant decomposition D. Kharzeev, Proc.Int.Sch.Phys.Fermi 130 (1996) 105-131 Access nucleon mass through trace of energy- momentum tensor (EMT) at zero momentum transfer µ | P i = 2 P µ P µ = 2 M 2 h P | T µ p At low momentum transfer: heavy quarks decouple ˜ β ( g ) 2 g G 2 + m q (1 + γ m ) ¯ X T µ µ = ψ q ψ q q = u,d,s Trace Anomaly Light Quark Mass Trace anomaly term dominant: 
 “ Proton mass result of the vacuum polarization induced by the presence of the proton.” S. Joosten 12

The proton mass : covariant decomposition D. Kharzeev, Proc.Int.Sch.Phys.Fermi 130 (1996) 105-131 Access nucleon mass through trace of energy- momentum tensor (EMT) at zero momentum transfer µ | P i = 2 P µ P µ = 2 M 2 h P | T µ p At low momentum transfer: heavy quarks decouple ˜ β ( g ) 2 g G 2 + m q (1 + γ m ) ¯ X T µ µ = ψ q ψ q q = u,d,s Trace Anomaly Light Quark Mass Experimental access: M. Luke et al. , PLB 288 (1992) 355-359 Trace of EMT proportional to quarkonium-proton scattering amplitude T ψ p Lattice QCD: Possible to evaluate < G 2 > directly S. Joosten 12