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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

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6/26/2015Ming X. Liu INT Workshop2 Drawing from D. Sivers @Santa Fe Polarized Drell-Yan Workshop Dinner 10/31-11/1, 2010

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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 Twist-3: sign change from gluonic-pole in hard parts In the overlapped region – consistent description 6/26/20153Ming X. Liu INT Workshop Collins ‘02 Ji, Qiu, Vogelsang, Yuan ‘06 Bacchetta, Boer, Diehl, Mulders ‘08

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Nice things about heavy quarks Experimentally tag Fermion and anti-Fermion Theoretically “clean” to use pQCD – M Q >> Λ QCD – Hard fragmentation 6/26/2015Ming X. Liu INT Workshop4

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5 Do we understand the physics? The Challenge of “Too Large” PRD65, 092008 (2002) PRL36, 929 (1976) ZGS 12 GeV beam AGS 22 GeV beam FNAL 200 GeV beam PLB261, 201 (1991) PLB264, 462 (1991) RHIC 20,000 GeV beam Non-Perturbative cross section Perturbative cross section PRL (2004) Large Transverse Single Spin Asymmetry (SSA) in forward meson production persists up to RHIC energy. 6/26/2015

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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! 6/26/20156Ming X. Liu INT Workshop

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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 6/26/20157Ming X. Liu INT Workshop

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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, A N (charm) provide new insight to the underlying physics of TSSA – Directly test the different color structure for quark and anti-quark 6/26/20158 A new clean experimental test of the color coupling to quark vs antiquark in hard scatterings! Ming X. Liu INT Workshop

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TSSA in Heavy Quark Production Kang, Qiu, Vogelsang, Yuan, PRD 2008 6/26/20159Ming X. Liu INT Workshop

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6/26/201510Ming X. Liu INT Workshop Open Charm TSSA in Twist-3 Approach

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TSSA in Charm Production at Low Energy (I) Low energy Initial state interactions Final state interactions 6/26/2015Ming X. Liu INT Workshop11 F. Yuan and J. Zhou PLB 668 (2008) 216-220

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Heavy Quark TSSA at Low Energy (cont.) Twist-3 quark-gluon correlation fun. Different color factors for charm and anti-charm Charmanti-CharmInitial state F. Yuan and J. Zhou PLB 668 (2008) 216-220 6/26/201512Ming X. Liu INT Workshop

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JPARC p+p GSI: p+pbar 6/26/201513Ming X. Liu INT Workshop

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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

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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 6/26/201515Ming X. Liu INT Workshop

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The Physics Goals Experimental 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 A N (c) and A N (c-bar) The process dependence of TSSA can be tested experimentally – DY vs DIS – Charm (quark) vs anti-charm (anti-quark) – Other processes.. 6/26/201516Ming X. Liu INT Workshop

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Experimental Prospects RHIC – @high energy Other facilities @low energy – JPARC – GSI/FAIR – Fermilab – EIC 6/26/201517Ming X. Liu INT Workshop

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Open Charm Production in p+p with PYTHIA (LO) 6/26/201518Ming X. Liu INT Workshop E906 RHIC 62GeV JAPRC RHIC 200 GeV

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Charm Production p+p @200GeV At low pT, g+g dominates 6/26/201519Ming X. Liu INT Workshop LONLO

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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 6/26/201520Ming X. Liu INT Workshop

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

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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

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23 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 Arms 1.2 < |η| < 2.4 Muon tracker (MuTr) Muon Identifier (MuID) Year s [GeV] Recorded LPol [%]FOM (P 2 L) 2006 (Run 6)2002.7 pb -1 51700 nb -1 2008 (Run 8)2005.2 pb -1 461100 nb -1 e+e+ e-e- μ+μ+ μ-μ-

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24 J/ψ Measurements in the Muon and Central Arms In Muon Arm A N Incl : oppositely-charged muon pairs in the invariant mass range ±2σ around J/ψ mass. A N BG : 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{N e+e+ N e-e- } Remaining continuum background Is small, not enough statistics Assuming: A N BG =0 arXiv: 1009.4864

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25 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. X. Wang, SPIN2010, arXiv: 1009.4864 - 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. J/ψ A N at Forward Rapidity

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26 NRQCD and J/ψ Production 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 PHENIX, PRL 92, 051802 (2004)

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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…

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Near Future Prospects PHENIX Silicon VTX Upgrades: by 2011 Ming X. Liu Seminar@UNM28 Precision Charm/Beauty Measurements B J/ , Drell-Yan, ’ Drell-Yan prompt 10/26/10

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Charm SSA to Probe Gluon Sivers Distribution 29 Kang, Qiu, Yuan, Vogelsang, Phys. Rev. D 78,114013(2008) 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 Ming X. Liu INT Workshop6/26/2015

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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 Sivers function(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… 6/26/201530Ming X. Liu INT Workshop

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Charm TSSA @EIC Open charm J/Psi Need model calculations 6/26/2015Ming X. Liu INT Workshop31 Kang and Qiu PRD (2008)

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EIC: J/Psi TSSA (I) TSSA could be closely connected to J/Psi production mechanisms F. Yuan PRD 70, 074025 6/26/201532Ming X. Liu INT Workshop

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EIC: J/Psi SSA (II) Color octet channel 6/26/201533Ming X. Liu INT Workshop

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New Idea: High Luminosity Polarized Fixed Target p+p? Drell-Yan Open charm@ low √s 6/26/2015Ming X. Liu INT Workshop34

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Ming X. Liu Seminar@UNM35 Example (I): E906 Drell-Yan Polarized DY possibility: Polarized targets Polarize the Main Injector Or both 120 GeV proton beam 4.9m X Beam X Target 10/26/10

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Ming X. Liu Seminar@UNM36 UVA/J-Lab/SLAC Polarized proton/deuteron target Polarized NH 3 /ND 3 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 ~ 10 35 (Hall C) ~ 10 34 (Hall B) D. Crabb MENU10 10/26/10

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Ming X. Liu Seminar@UNM37 Expected DY A N Sensitivity @120 GeV. Target - 6 cm NH 3 - 10 19 proton 10/26/10 Also open charm and J/psi

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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 6/26/201538Ming X. Liu INT Workshop

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Backup 6/26/2015Ming X. Liu INT Workshop39

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6/26/2015Ming X. Liu INT Workshop40 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 Drell Yan beauty charm combinatorial background DCA < 1 σ cut: Increase DY/bb ~ 5 ϒ-states J/Ψ Drell Yan charm beauty DY: 4 GeV < M < 9 GeV; B-background: use FVTX

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Ming X. Liu Seminar@UNM41 Example (II): Polarized DY w/ Fixed Target @RHIC ? Polarized fixed target DY exp. with extracted polarized proton beams: PHENI X STAR BRAHMS Fixed Target DY Exp. @Beam Dump 1.High density LH 2 /LD 2 target 2.High density polarized targets 3Map out x-dep. - 250 GeV proton beams - Pol up to 70% 10/26/10

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Ming X. Liu Seminar@UNM42 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 – Dimu x-section @ 250 GeV (M>4) ~20pb Targets – E906-like unpolarized LH 2 target 51cm LH2 (2.1x10 24 /cm 2 ) Can handle L ~ 1x10 36 cm -2 s -1 – Polarized solid target UVA/J-Lab/SLAC: L ~10 35 cm -2 s -1 Advantages – Polarized beams – (polarized) targets – Higher Energy and large x-coverage – High luminosity 10/26/10

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Ming X. Liu Seminar@UNM43 DY A N Sensitivity @250 GeV Fixed Target 4.5<M<8 GeV q T < 1 GeV 10 fb -1 50 fb -1 xFxF 10/26/10

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Open charm at fixed target (cross section) 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 s 1/2 dependence of the calculation mainly reflects the underlying PDF. s 1/2 (GeV) cc in pN, N

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Charm production 6/26/2015Ming X. Liu INT Workshop45

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Ming X. Liu Seminar@UNM46 Proton Efficiency: Collider vs Fixed Target Mode Design value: 2x10 11 x100 = 2 x 10 13 proton per store per ring Collision rate ~ 10 MHz – Num. of collisions per store – 10M x 3600sec x 8 hr = 2.9 x 10 10 – Fract. of p’s used = 3 x10 11 / 2 x 10 13 = 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 10/26/10

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Color Flow in Twist-3 Kang @RBRC workshop 2010 6/26/201547Ming X. Liu INT Workshop

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Generalized Parton Model Assume TMD factorization 6/26/201548Ming X. Liu INT Workshop Anselmino et al. TMD factorization breakdown… a failure or an opportunity? Mulders, Xiao.. @RBRC workshop 2010

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