Polarized Drell-Yan Experiment at J-PARC. J-PARC Meeting for Spin and Hadron Physics Nishina Hall at RIKEN April 7 th, 2008 Yuji Goto (RIKEN/RBRC)

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1 Polarized Drell-Yan Experiment at J-PARC J-PARC Meeting for Spin and Hadron Physics Nishina Hall at RIKEN April 7 th, 2008 Yuji Goto (RIKEN/RBRC)

2 J-PARC proposals P04: measurement of high-mass dimuon production at the 50-GeV proton synchrotron spokespersons: Jen-Chieh Peng (UIUC) and Shinya Sawadas (KEK) collaboration: Abilene Christian Univ., ANL, Duke Univ., KEK, UIUC, LANL, Pusan National Univ., RIKEN, Seoul National Univ., TokyoTech, Tokyo Univ. of Science, Yamagata Univ. including polarized physics program, but not discussed deferred P24: polarized proton acceleration at J-PARC contact persons: Yuji Goto (RIKEN) and Hikaru Sato (KEK) collaboration: ANL, BNL, UIUC, KEK, Kyoto Univ., LANL, RCNP, RIKEN, RBRC, Rikkyo Univ., TokyoTech, Tokyo Univ. of Science, Yamagata Univ. polarized Drell-Yan included as a physics case no decision Next proposal for the polarized physics program to be submitted April 7,

3 Origin of the nucleon spin /2? = 2 ΔΣ + Δg + L EMC experiment at CERN total quark spin constitutes a small fraction of the nucleon spin ΔΣ = 2 ± 9(stat) ± 4(syst)% integration in x = 0 ~ makes uncertainty more data to cover wider x region with more precise data necessary SLAC/CERN/DESY/JLAB experiments Gluon spin contribution? scaling violation in polarized DIS success of the evolution equation of the perturbative QCD limited sensitivity due to a limited range of Q 2 semi-inclusive polarized DIS polarized hadron collision Orbital angular momentum? 2 J. Ashman et al., NPB 328, (989). proton spin crisis ΔΣ ~ 20% longitudinally polarized measurements A LL transversely polarized measurements April 7, = dσ dσ dσ dσ + +

4 Gluon spin contribution A LL in neutral pion production mid-rapidity at RHIC, s = 200 GeV A = [ ω ] ΔgΔg + [ ω Δq] Δg + [ ω ΔqΔq] LL gg gq qq ΔG = 0.4 at Q 2 =(GeV/c) 2 gg + qg dominant sensitive to the gluon reaction ΔG = 0. at Q 2 =(GeV/c) 2 GRSV-std scenario, ΔG = 0.4 at Q 2 = (GeV/c) 2, excluded by data on more than 3-sigma level April 7,

5 Flavor-sorted quark polarization Weak boson production A W L + RHIC spin s = 500 GeV 2009 parity-violating asymmetry A L = Δu( x u( x a a ) d ( x ) d ( x b b ) Δd ( xa ) u( x ) + d ( x ) u( x ) reduction of uncertainties to determine the quak spin contribution ΔΣ and gluon spin contribution ΔG to the proton spin a b b ) April 7,

6 Transverse single-spin asymmetry (SSA) Link to orbital angular momentum in the nucleon forward rapidity Fermilab E704, s = 20 GeV RHIC, s = 200 GeV π + π K ± p p explained by many undetermined distribution and fragmentation functions: transversity, Sivers function, Collins function April 7,

7 Drell-Yan experiment The simplest process in hadron-hadron reactions DIS Drell-Yan l no QCD final-state effect no polarized Drell-Yan experiment done yet flavor asymmetry of the sea-quark distributions unpolarized and longitudinally-polarized measurements orbital angular momentum in the nucleon Sivers effect (no Collins effect) transversity distribution function, etc. Why at J-PARC? polarized beam feasible in discussions with J-PARC and BNL accelerator physicists high intensity/luminosity for small Drell-Yan cross section April 7, l

8 Flavor asymmetry of sea-quark distribution Fermilab E866 σ Possible origins meson-cloud model 2 virtual meson-baryon state instanton model chiral quark soliton model pd ~ d ( x + 2) u ( x ) pp 2σ p pπ, nπ, chiral quark model Δπ April 7, σ pd /2σ pp FNAL E866/NuSea Drell-Yan Drell-Yan J/ψ ϒ(S) ϒ(2S) with CTEQ5M MRST CTEQ4M CTEQ5M CTEQ4M (d _ - u _ = 0) % Systematic error not shown x 2 dx[ d ( x) u ( x)] = ± 0.0 dx[ d ( x) u ( x)] = 0.8 ± 0.02 GRV98

9 Flavor asymmetry of sea-quark distribution π + is the origin of d -quark excess in the proton? April 7,

10 Dimuon experiment at J-PARC (P04) based on the Fermilab spectrometer for 800 GeV length to be reduced but the aperture to be increased two vertically bending magnets with p T kick of 2.5 GeV/c and 0.5 GeV/c tracking by three stations of MWPC and drift chambers muon id and tracking tapered copper beam dump and Cu/C absorbers placed within the first magnet April 7,

11 Polarized Drell-Yan experiment at J-PARC Longitudinally-polarized measurement A LL measurement flavor asymmetry of sea-quark polarization GS-C GS-A GRSV chiral quark soliton model prediction 20-day run 75% polarization for a 5 0 protons/spill polarized solid NH3 target, 75% hydrogen polarization and 0.5 dilution factor April 7, 2008

12 Flavor asymmetry of sea-quark polarization Polarized Drell-Yan experiment at J-PARC x = W ± production at RHIC x = GS-C GS-A GRSV reduction of uncertainties to determine the quak spin contribution ΔΣ and gluon spin contribution ΔG to the proton spin April 7,

13 Polarized Drell-Yan experiment at J-PARC Orbital angular momentum in hadron-hadron reaction, no direct link between measurement and theory (yet) but, any partonic transverse motion and correlation should be related Sivers effect / higher-twist effect SSA (A N ) measurement Sivers effect and higher-twist effect provide the same description of SSA on Drell-Yan and semi-inclusive DIS at moderate q T : Λ QCD << q T << Q Sivers function in Drell-Yan should have a sign opposite to that in DIS sensitive QCD test between e+p data and p+p data 4 < M μ+μ- < 5 GeV integrated over q T 000 fb- (20-day run), 75% polarization, no dilution factor Theory calculation by Ji, Qiu, Vogelsang and Yuan based on Sivers function fit of HERMES data April 7,

14 April 7, Polarized Drell-Yan experiment at J-PARC A TT measurement h (x): transversity remaining leading-order distribution function of the nucleon SSA measurement, sin(φ+φ S ) term h (x): transversity h () (x): Boer-Mulders function ( st moment of) θ φ φ φ θ cos ) cos(2 sin ˆ 2)) ( ) ( ) ( ( 2)) ( ) ( ) ( ( ˆ 2 + = + + = S S TT q q q q q q q q TT TT a x f x f e x h x h e a A + + = q q q q q q q q x f x f e x h x h e A 2)) ( ) ( ) ( ( 2)) ( ) ( ) ( ( 2 ˆ () 2

15 Unpolarized Drell-Yan experiment at J-PARC Boer-Mulders function h (x, k T2 ) angular distribution of unpolarized Drell-Yan ν dσ 3 2 ν 2 = λ cos θ μsin2θcosφ sin θcos2φ σ d 4π Ω Lam-Tung relation reflect the spin-/2 nature of quarks λ = 2ν violation of the Lam-Tung relation suggests nonperturbative origin ν 0, λ 2ν correlation between transverse quark spin and quark transverse momentum p + d at 800 GeV/c π - + W at 252 GeV/c π - + W at 94 GeV/c With Boer-Mulders function h : ν(π - W µ + µ - X)~valence h (π)*valence h (p) ν(pd µ+µ-x)~valence h (p)*sea h (p) L.Y. Zhu,J.C. Peng, P. Reimer et al. hep-ex/ p April 7, 2008 T (GeV/c) 5

16 Experimental condition study Previous simulation study which made the figure below was wrong target position was fixed at z = 0 (at the edge of the first magnet) correctly, this should be z = -800 cm ~ -300 cm (50 cm target) yield should be ~5 times smaller PYTHIA simulation: mass = 4 5 GeV/c 2 beam intensity: 5 0 ppp = 0 /sec 20 day = 0 7 sec beam on target: (with 50% duty factor) number density of liq.h 2 target: 0.429x0 23 /cm 3 luminosity = bot number density target length = 000 fb fb - (20-day run), 75% polarization, no dilution factor Theory calculation by Ji, Qiu, Vogelsang and Yuan based on Sivers function fit of HERMES data but, higher beam intensity is possible for unpolarized liq.h 2 target 0 times higher possible? ppp = 0 2 /sec? April 7,

17 Experimental condition study J-PARC experiment should be optimized for 4 GeV/c 2 virtual photon PYTHIA simulation: mass = 4 4. GeV/c 2, x F = each of magnet/detector geometry same as E906, but total apparatus length 60% shorter April 7,

18 Experimental condition study E906 optimized for 7 GeV/c 2 virtual photon PYTHIA simulation mass = 7 7. GeV/c 2, x F = mass = 4 4. GeV/c 2, x F = April 7,

19 Experimental condition study Smaller boost wider aperture of the first magnet necessary Sivers effect measurement single beam-spin asymmetry maybe easier to use nuclear targets More studies absorber & beam target thickness, etc. trigger rate and resolution April 7,

20 pqcd studies by Yokoya-san, et al. NLO/NNLO April 7,

21 pqcd studies by Yokoya-san, et al. Scheme dependence April 7,

22 pqcd studies by Yokoya-san, et al. April 7,

23 pqcd studies by Yokoya-san, et al. April 7,

24 pqcd studies by Yokoya-san, et al. April 7,

25 pqcd studies by Yokoya-san, et al. April 7,

26 pqcd studies by Yokoya-san, et al. April 7,

27 pqcd studies by Yokoya-san, et al. April 7,

28 pqcd studies by Yokoya-san, et al. s = 62 GeV April 7,

29 pqcd studies by Yokoya-san, et al. s = 0 GeV April 7,

30 pqcd studies by Yokoya-san, et al. April 7,

31 pqcd studies by Kawamura-san, et al. April 7,

32 pqcd studies by Kawamura-san, et al. April 7,

33 Summary Polarized Drell-Yan experiment with dimuon measurment using polarized proton beam at J-PARC has a rich physics programs flavor asymmetry of sea-quark polarization higher precision for ΔΣ and ΔG SSA measurements for Sivers and higher-twist effects and transversity link to orbital-angular momentum We propose to make the J-PARC facility allow acceleration of polarized proton beams to GeV feasible in discussion with J-PARC and BNL accelerator physicists technically, there is no showstopper Theoretical studies at J-PARC energy has progressed showing convergence to compare with experimental data More studies for experimental condition to be done for the next proposal April 7,