1 / 48

Probing the Color Gauge Link via Heavy Quark TSSA in p+p Collisions

Probing the Color Gauge Link via Heavy Quark TSSA in p+p Collisions. Ming X . Liu Los Alamos National Lab INT Spin Workshop 11/2010 A new Experimental Test of color d ynamics in hard scattering TSSA for Open ( anti)charm , J/Psi and DY Test color structures for quark and anti-quark

deliz
Download Presentation

Probing the Color Gauge Link via Heavy Quark TSSA in p+p Collisions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Probing the Color Gauge Link via Heavy Quark TSSA in p+p Collisions Ming X. Liu Los Alamos National Lab INT Spin Workshop 11/2010 A new Experimental Test of color dynamics in hard scattering TSSA for Open (anti)charm, J/Psi and DY Test color structures for quark and anti-quark Experimental opportunity: RHIC and other future Exp’s An experimentalist’s point of approach

  2. The magic of sign change Drawing from D. Sivers @Santa Fe Polarized Drell-Yan Workshop Dinner 10/31-11/1, 2010 Ming X. Liu INT Workshop

  3. Color Flow in DY and DIS • The sign change – a new fundamental test of color gauge formalism • Charm TSSA could provides a new independent experimental test of the underlying physics Collins ‘02 Twist-3: sign change from gluonic-pole in hard parts In the overlapped region – consistent description Ji, Qiu, Vogelsang, Yuan ‘06 Bacchetta, Boer, Diehl, Mulders ‘08 Ming X. Liu INT Workshop

  4. Nice things about heavy quarks • Experimentally tag Fermion and anti-Fermion • Theoretically “clean” to use pQCD • MQ >> ΛQCD • Hard fragmentation Ming X. Liu INT Workshop

  5. RHIC 20,000 GeV beam Do we understand the physics?The Challenge of “Too Large” Large Transverse Single Spin Asymmetry (SSA) in forward meson production persists up to RHIC energy. FNAL 200 GeV beam AGS 22 GeV beam ZGS 12 GeV beam PRL (2004) PLB261, 201 (1991) PLB264, 462 (1991) PRD65, 092008 (2002) PRL36, 929 (1976) Perturbative cross section Non-Perturbative cross section Ming X. Liu INT Workshop

  6. Color Interaction and TSSA • Do we understand the underlying physics? • the Sivers asymmetry, for example • What can we learn more from future data? • DY, charm, direct-photon… We are colliding hadrons, not partons! Ming X. Liu INT Workshop

  7. Gamberg, Kang 2010 Generalizing GPM… with modified hard cross sections (gluonic-pole cross sections) PRL 99 (2007) A. Bacchetta et al, PRD 72 (2005) A. Bacchetta, C.J. Bomhof, P.J.Mulders, F.Pijlman Ming X. Liu INT Workshop

  8. Charm and anti-Charm TSSA and Color Structure • Quark and anti-Quark have different color structure in hard scatterings • Experimentally Charm and anti-Charm can be cleanly identified, • AN(charm) provide new insight to the underlying physics of TSSA • Directly test the different color structure for quark and anti-quark A new clean experimental test of the color coupling to quark vs antiquark in hard scatterings! Ming X. Liu INT Workshop

  9. TSSA in Heavy Quark Production Kang, Qiu, Vogelsang, Yuan, PRD 2008 Ming X. Liu INT Workshop

  10. Open Charm TSSA in Twist-3 Approach Ming X. Liu INT Workshop

  11. TSSA in Charm Production at Low Energy (I) F. Yuan and J. Zhou PLB 668 (2008) 216-220 • Low energy • Initial state interactions • Final state interactions Ming X. Liu INT Workshop

  12. Heavy Quark TSSA at Low Energy (cont.)Twist-3 quark-gluon correlation fun. • Different color factors for charm and anti-charm F. Yuan and J. Zhou PLB 668 (2008) 216-220 Initial state Charm anti-Charm Ming X. Liu INT Workshop

  13. JPARC p+p GSI: p+pbar Ming X. Liu INT Workshop

  14. Sensitive to gluon Sivers function * probe gluon’s orbital angular momentum? -- Minimize Collins’ effects * heavy flavor production dominated by gluon gluon fusion at RHIC energy Pythia 6.1 simulation (LO) * gluon has zero transversity Tri-gluon correlation functions Also sensitive to J/ψ production mechanisms and QCD dynamics Heavy Flavor TSSA @RHIC Open Charm Johann Riedl, SPIN2008

  15. Heavy Quark SSA at High Energy (II)Twist-3 tri-gluon correlation • Consequence of different color factors for charm and anti-charm Kang et al 2008 Koike et al 2010 Ming X. Liu INT Workshop

  16. The Physics GoalsExperimental Study of the Color Flow via Open Heavy Quark TSSA • Current understanding of TSSA based on the color gauge invariant QCD formalism • Twist-3, modified GPM … • Expect significant difference between AN(c) and AN(c-bar) • The process dependence of TSSA can be tested experimentally • DY vs DIS • Charm (quark) vs anti-charm (anti-quark) • Other processes .. Ming X. Liu INT Workshop

  17. Experimental Prospects • RHIC – @high energy • Other facilities @low energy • JPARC • GSI/FAIR • Fermilab • EIC Ming X. Liu INT Workshop

  18. Open Charm Production in p+pwith PYTHIA (LO) RHIC 200 GeV RHIC 62GeV E906 JAPRC Ming X. Liu INT Workshop

  19. Charm Production p+p @200GeV • At low pT, g+g dominates LO NLO Ming X. Liu INT Workshop

  20. More on Open Charm Production • Fixed targets vs NLO • Collider mode @RHIC PRL 95, 122001 (2005) M. Cacciari, P. Nason, R. Vogt EPJ C 52, 987 (2007) J. Riedl, A. Schafer, M. Stratmann Ming X. Liu INT Workshop

  21. Measurement for m- Forward Open (anti)Charm AN D (m-) • D meson production dominated by gluon-gluon fusion at RHIC energy • Sensitive to gluon Sivers effect • AN measured for muons from D decay • Smear by decay kinematics Gluon Sivers=Max Gluon Sivers=0 Calculations for D mesons Anselmino et al, PRD 70, 074025 (2004)

  22. TSSA and J/Ψ Production J/ψ TSSA is sensitive to the production mechanisms Assuming a non-zero gulon sivers function, In pp scattering, TSSA vanishes if the pair are produced in a color-octet model but survives in the color-singlet model Feng Yuan, Phys. Rev D78, 014024(2008) One color-singlet diagram — no cancellation, asymmetry generated by the initial state interaction Two color-octet diagrams — cancellation between initial and final state interactions, no asymmetry In Collinear higher twist approach, the relation is not quiet simple. There are partial but not full cancellation of terms. Z. Kang

  23. e+ e- μ+ μ- PHENIX Detector • Central Arm|| < 0.35 • Drift Chamber (DC) • PbGl and PbSc • Ring Imaging Cherenkov Detector (RICH) • Pad Chambers (PC) • Time Expansion Chamber (TEC) • Global Detectors (Luminosity,Trigger) • BBC • ZDC • Muon Arms1.2 < |η| < 2.4 • Muon tracker (MuTr) • Muon Identifier (MuID)

  24. In Muon Arm ANIncl:oppositely-charged muon pairs in the invariant mass range ±2σ around J/ψ mass. ANBG:oppositely-charged muon pairs in the invariant mass range 1.8 (2.0run8) < m <2.5 along with charged pairs of the same sign in invariant mass range 1.8 (2.0run8) < m< 3.6 In Central Arm BG subtraction: 2*sqrt{Ne+e+Ne-e-} Remaining continuum background Is small, not enough statistics Assuming: ANBG=0 J/ψ Measurements in the Muon and Central Arms arXiv: 1009.4864

  25. J/ψ AN at Forward Rapidity X. Wang, SPIN2010, arXiv: 1009.4864 Asymmetries were obtained as a function of J/Psi Feynman-x, with a value of -0.086 ± 0.026 (stat.) ± 0.003 (sys.) in the forward region. - Suggests possible non-zero tri-gluon correlation functions in transversely polarized protons. - If well defined in this reaction, the results suggests non-zero gluon Sivers distribution functions.

  26. NRQCD and J/ψ Production PHENIX, PRL 92, 051802 (2004) Theoretical predictions of J/Ψ production at RHIC are in good agreement with the PHENIX data: COM process dominant • PRD 68 (2003) 034003 G. Nayak, M. Liu, F. Cooper • PRL 93 (2004) 171801 F. Cooper, M. Liu, G. Nayak

  27. NRQCD and J/ψ Polarization NRQCD failed on J/ψ polarization. J/ψ production mechanism is still an open question. Very active field of theoretical study…

  28. Drell-Yan prompt pm Near Future ProspectsPHENIX Silicon VTX Upgrades: by 2011 • Precision Charm/Beauty Measurements • BJ/, Drell-Yan, ’ Ming X. Liu Seminar@UNM

  29. Charm SSA to Probe Gluon Sivers Distribution • D meson Single-Spin Asymmetry: • Production dominated by gluon-gluon fusion • Sensitive to gluon Sivers distribution • PHENIX-2006 data ruled out the max. gluon Sivers • Much improved results expected with VTX detectors Kang, Qiu, Yuan, Vogelsang, Phys. Rev. D 78,114013(2008) Ming X. Liu INT Workshop

  30. A few Observations and Comments • Twist-3 and Generalized TMD Parton Model • Color gauge approach • Quark sector: some knowledge • Quark Sivers and Collins functions • Twist-3 quark-gluon correlation functions • Gluon sector: largely unknown • Gluon Siversfunction(s)?? • Twist-3 tri-gluon correlation functions • Next experimental step for p+p • Heavy quark probe! • Directly access the color charge coupling to quark and anti-quark • Multi probes in a wide kinematic range • High luminosity polarized fixed target Drell-Yan and Charm experiment? • It is all about the color flow in hard scattering • TSSA @RHIC-SPIN • p/d+A @RHIC • Jlab-12, EIC… Ming X. Liu INT Workshop

  31. Charm TSSA @EIC • Open charm • J/Psi • Need model calculations Kang and Qiu PRD (2008) Ming X. Liu INT Workshop

  32. EIC: J/Psi TSSA (I) • TSSA could be closely connected to J/Psi production mechanisms F. Yuan PRD 70, 074025 Ming X. Liu INT Workshop

  33. EIC: J/Psi SSA (II) • Color octet channel Ming X. Liu INT Workshop

  34. New Idea: High Luminosity Polarized Fixed Target p+p? • Drell-Yan • Open charm@ low √s Ming X. Liu INT Workshop

  35. Example (I): E906 Drell-Yan Polarized DY possibility: Polarized targets Polarize the Main Injector Or both 120 GeV proton beam 4.9m XTarget XBeam Ming X. Liu Seminar@UNM

  36. D. Crabb MENU10 UVA/J-Lab/SLAC Polarized proton/deuteron target • Polarized NH3/ND3 targets • Dynamical Nuclear Polarization • Operate at 5 T and 1 K. Pol ~ B/T • Used with high beam intensities – up to ~100 nA • Large capacity pumps • Polarizations: • p > 90%, • d ~ 50% • Able to handle high luminosity • up to ~ 1035 (Hall C) ~ 1034 (Hall B) Ming X. Liu Seminar@UNM

  37. Expected DY AN Sensitivity @120 GeV. • Target • 6 cm NH3 • 1019 proton Also open charm and J/psi Ming X. Liu Seminar@UNM

  38. Summary and Outlook • Experimental confirmation (or disproval) of color flow dynamics in hard scattering is a critical step toward understanding the mechanisms of SSA • Drell-Yan • Charm vs anti-Charm • Future experimental prospects – exciting opportunity! • RHIC, high energy • EIC • Polarized fixed targets, low energy Ming X. Liu INT Workshop

  39. Backup Ming X. Liu INT Workshop

  40. Drell Yan charm beauty Drell Yan combinatorial background ϒ-states J/Ψ charm beauty • DY: 4 GeV < M < 9 GeV; B-background: use FVTX Critical Role of VTX/FVTX for Drell-Yan and Open Charm • Tracking muons with MuTr+FVTX • Prompt muons from DY • Displaced tracks from π/K and heavy quark decays DCA < 1 σ cut: Increase DY/bb ~ 5 Ming X. Liu INT Workshop

  41. BRAHMS PHENIX STAR Example (II): Polarized DY w/ Fixed Target @RHIC ? Polarized fixed target DY exp. with extracted polarized proton beams: • Fixed Target DY Exp. • @Beam Dump • High density LH2/LD2 target • High density polarized targets • 3 Map out x-dep. - 250 GeV proton beams - Pol up to 70% Ming X. Liu Seminar@UNM 41

  42. Fixed Target @RHIC ? • Beam dump experiment: dimuon channel • Parasitic mode • Significant beams still left at the end of a store (~50%) • Cycle time ~8hr • Dedicated fixed target • Cycle time ~ 1hr • Dimux-section @ 250 GeV (M>4) ~20pb • Targets • E906-like unpolarized LH2 target • 51cm LH2 (2.1x1024/cm2) • Can handle L ~ 1x1036cm-2s-1 • Polarized solid target • UVA/J-Lab/SLAC: L ~1035cm-2s-1 • Advantages • Polarized beams • (polarized) targets • Higher Energy and large x-coverage • High luminosity Ming X. Liu Seminar@UNM

  43. DY AN Sensitivity@250 GeV Fixed Target 4.5<M<8 GeV qT < 1 GeV 10 fb-1 50 fb-1 xF Ming X. Liu Seminar@UNM

  44. Open charm at fixed target (cross section) scc in pN,pN • Charm cross section by fixed target experiments are reasonably reproduced by LO pQCD event generator (PYTHIA) with large K-factor, or by NLO pQCD calculation (HVQMNR). Note that pQCD may or may not be applicable to charm production because charm mass is small (~1.5GeV) • In the left figure, world pi+N data and p+N data are compared with PYTHIA calculation. The s1/2 dependence of the calculation mainly reflects the underlying PDF. s1/2(GeV)

  45. Charm production Ming X. Liu INT Workshop

  46. Proton Efficiency: Collider vs Fixed Target Mode • Design value: 2x1011x100 = 2 x 1013 proton per store per ring • Collision rate ~ 10 MHz • Num. of collisions per store • 10M x 3600sec x 8 hr = 2.9 x 1010 • Fract. of p’s used = 3 x1011 / 2 x 1013 = 1.5 x 10-2 • In the fixed target mode, for a ~20% interaction length, we can use ~20% of the protons from the beam • 0.2/ 1.5 x 10-2 = 13x gain in luminosity • Center of Mass Energies for p+p • Collider mode: sqrt(s) = 500 GeV • Fixted T mode: sqrt(s) = 22 GeV Ming X. Liu Seminar@UNM

  47. Color Flow in Twist-3 Kang @RBRC workshop 2010 Ming X. Liu INT Workshop

  48. Generalized Parton Model • Assume TMD factorization Anselmino et al. TMD factorization breakdown… a failure or an opportunity? Mulders, Xiao.. @RBRC workshop 2010 Ming X. Liu INT Workshop

More Related