more correctly target polarization beam polarization depolarization factor
核子スピン1/2の起源 ? • 偏極レプトン深非弾性散乱実験 more correctly – 実験データ target polarization beam polarization depolarization factor 2007年 10月19日(金) 5
QCD factorization – ex. hadron production in proton collisions • pp h. X parton distribution function (PDF) fragmentation function (FF) partonic cross section long distance term short distance term factorization scale – boundary between short and long distance 2007年 10月19日(金) 10
Global QCD analysis • framework to combine various experimental data into a systematically controlled extraction of the unpol. & pol. PDFs, FFs – experimental data adata(x, Q 2) with experimental errors adata(x, Q 2) – function form (parametrizations) of PDFs and FFs satisfying physical requirements at the initial Q 20 – Q 2 evolution of PDFs/FFs and theoretical calculation corresponding to the experimental data acalc(x, Q 2) – 2 analysis (minimization) – parameters (and errors on the parameters) determined 2007年 10月19日(金) 11
グルーオンスピンの寄与 • 偏極ハドロン衝突実験 – double helicity asymmetry – leading-order グルーオン測定 • 光子の直接生成 • 重いフレーバー生成 proton beam or or gluon photon gluon or or proton beam 2007年 10月19日(金) heavy flavor 13
RHICスピン計画@BNL • 偏極陽子衝突型加速器 – エネルギー 200 Ge. V (将来は 500 Ge. V) – 偏極度 60%以上 (目標は 70%) RHIC p. C Polarimeters BRAHMS & PP 2 PP Absolute Polarimeter (H jet) PHOBOS Siberian Snakes PHENIX STAR Spin Rotators (longitudinal polarization) Solenoid Partial Siberian Snake Pol. H Source LINAC Spin flipper Spin Rotators (longitudinal polarization) BOOSTER Helical Partial Siberian Snake 200 Me. V Polarimeter AGS Internal Polarimeter Rf Dipole AGS p. C Polarimeters Strong AGS Snake 2007年 10月19日(金) 15
生成断面積測定 • perturbative QCD applicable ? – dependence of the calculated cross section on represents an uncertainty in theoretical predictions M. Stratmann and W. Vogelsang 2007年 10月19日(金) 16
生成断面積測定 – comparison of 0 cross section between data and NLO perturbative-QCD calculations – agreement is excellent down even to p. T ~ 1 Ge. V/c mid-rapidity forward rapidity 2007年 10月19日(金) 17
グルーオンスピンの寄与 • PHENIX ALL in neutral pion production – mid-rapidity | | < 0. 35, s = 200 Ge. V G = 0. 4 at Q 2=1(Ge. V/c)2 G = 0. 1 at Q 2=1(Ge. V/c)2 gg + qg dominant sensitive to the gluon reaction 2007年 10月19日(金) 18
グルーオンスピンの寄与 • PHENIX ALL of 0 Calc. by W. Vogelsang and M. Stratmann – GRSV-std scenario, G = 0. 4 at Q 2 = 1(Ge. V/c)2, excluded by data on more than 3 -sigma level, 2(std) 2 min > 9 • only experimental statistical uncertainties included (the effect of systematic uncertainties expected to be small in the final results) • theoretical uncertainties not included 2007年 10月19日(金) 19
グルーオンスピンの寄与 • STAR ALL of jet 2005 STAR preliminary GRSV DIS Systematic error band Measured Jet PT (Ge. V/c) 2007年 10月19日(金) 20
グルーオンスピンの寄与 • 直接生成光子 – mid-rapidity | | < 0. 35, s = 200 Ge. V – gluon compton process dominant ~75% proton beam or gluon photon or proton beam 2007年 10月19日(金) 21
クォーク偏極のフレーバー依存 • various quark and antiquark polarization individually – reduction of uncertainties to determine the quak spin contribution and gluon spin contribution G to the proton spin • semi-inclusive DIS – HERMES – Pqh(x, z): purity • unpolarized quantity 2007年 10月19日(金) 22
クォーク偏極のフレーバー依存 • weak boson production – RHIC spin • s = 500 Ge. V • 2009 – – parity-violating asymmetry AL – no fragmentation ambiguity – x-range limited 2007年 10月19日(金) 23
Single transverse-spin asymmetry • 左右非対称度 • 前方rapidity – Fermilab-E 704 • 固定標的実験 • s = 19. 4 Ge. V – RHIC-STAR • s = 200 Ge. V • x. F > 0. 3 で大きな非対称度 2007年 10月19日(金) 25
Single transverse-spin asymmetry • 前方ラピディティー – 非対称度 ~20% – 多くのQCDに基づく理論の開発 s = 19. 4 Ge. V s = 200 Ge. V Fermilab-E 704 Phys. Rev. Lett. 92 (2004) 171801 2007年 10月19日(金) 26
非偏極分布関数 Sivers関数 Helicity分布関数 Transversity分布関数 Boer-Mulders関数 2007年 10月19日(金) P. Mulders 28
中央ラピディティー • PHENIX – 異なる運動学的領域 • • • contribution from both gluon-gluon and quark-gluon reactions x = 0. 03 – 0. 1 small quark polarization/transversity no gluon transversity in leading twist negligible transversity & Collins effect contribution 2007年 10月19日(金) 30
中性子生成非対称度@IP 12 • performed in 2001 -2002 with s = 200 Ge. V polarized proton collisions at the 12 o’clock collision point ~ 1800 cm ± 2. 8 mrad Dx magnet 10 cm Blue beam yellow beam Hadron Cal hodoscope EM Cal Charged veto (plastic scinti. ) Post shower counter Steel To measure Collision point Gamma veto (plastic scinti. ) Lead block 2007年 10月19日(金) Neutron veto (plastic scinti. )31
中性子生成非対称度@IP 12 • Phys. Lett. B 650 (2007) 325. 2007年 10月19日(金) invariant mass of pairs of energy clusters 32
J-PARC facility Materials and Life Science Experimental Facility Hadron Beam Facility Nuclear Transmutation 500 m Neutrino to Kamiokande Linac (330 m) 3 Ge. V Synchrotron (25 Hz, 1 MW) 50 Ge. V Synchrotron (0. 75 MW) J-PARC = Japan Proton Accelerator Research Complex Joint Project between KEK and JAEA 2007年 10月19日(金) 34
J-PARC parameters • 50 Ge. V beam – – – repetition 3. 4 ~ 5 (or 6) sec flat top width 0. 7 ~ 2 (or 3) sec linac energy 400 Me. V 3. 3 1014 ppp, 15 A beam power 750 k. W • 30 Ge. V beam (phase-1) – linac energy 180 Me. V – 2 1014 ppp, 9 A – beam power 270 k. W 2007年 10月19日(金) 35
Hadron experimental hall (phase 1) beamlines for secondary beam experiments at the beginning of the phase 1 Experimental Area Test Beam A-Line Beam Dump (on the guide rail for Phase 2) area for primary beam experiments 2007年 10月19日(金) 36
Drell-Yan実験 • The simplest process in hadron-hadron reactions DIS Drell-Yan – no final-state effect from QCD – no polarized Drell-Yan experiment yet • Flavor asymmetry of the sea quark distribution – unpolarized and (longitudinally-)polarized • Orbital angular momentum in the proton? – Sivers effect (no Collins effect) • Transversity, etc. 2007年 10月19日(金) 37
Drell-Yan実験 • Why at J-PARC ? – polarized beam • feasible in discussions with J-PARC and BNL accelerator physicists – high intensity/luminosity • small Drell-Yan cross section • e. g. 1012 protons/sec, 10% target L = 2 1036/cm 2/sec 2007年 10月19日(金) 38
Sea-quark分布のflavor非対称性 • Gottfried sum rule – in the parton model with isospin symmetry – CERN NMC experiment 2007年 10月19日(金) 39
Sea-quark分布のflavor非対称性 • Fermilab E 866 Drell-Yan experiment – flavor asymmetry of the seq quark distribution 2007年 10月19日(金) 40
Sea-quark分布のflavor非対称性 • Physics origin – meson cloud model • virtual meson-baryon state – chiral quark model – instanton – chiral-quark soliton model 2007年 10月19日(金) 41
J-PARCでのdimuon実験 – based on the Fermilab spectrometer for 800 Ge. V, the length can be reduced but the aperture has to be increased – two vertically bending magnets with p. T kick of 2. 47 Ge. V/c and 0. 5 Ge. V/c – tracking is provided by three stations of MWPC and drift chambers – muon id and tracking are provided – 2 x 1012 50 Ge. V protons/spill tapered copper beam dump and Cu/C absorbers placed within the first magnet 2007年 10月19日(金) 43
J-PARCでのdimuon実験 • Unpolarized program – proton beam on proton and deuterium target 2007年 10月19日(金) 44
Spin physics at J-PARC • Polarized Drell-Yan – ALL measurement • flavor asymmetry of sea-quark polarization GS-C GS-A GRSV chiral quark soliton model prediction 120 -day run 75% polarization for a 5 1011 protons/spill polarized solid NH 3 target, 75% hydrogen polarization and 0. 15 dilution factor 2007年 10月19日(金) 45
Sea quark helicity distribution • Polarized Drell-Yan – x: 0. 25 – 0. 5 • W production at RHIC – x: 0. 05 – 0. 1 GS-C GS-A GRSV reduction of uncertainties to determine the quak spin contribution and gluon spin contribution G to the proton spin 2007年 10月19日(金) 46
Polarized Drell-Yan • AN measurement – Ji, Qiu, Vogelsang, and Yuan • PRD 73, 094017 (2006) • sensitive to higher-twist effect at high q. T ~ Q • Sivers effect and higher-twist effect provide the same description of SSA on Drell-Yan at moderate q. T: QCD << q. T << Q • similar for SSA on semi-inclusive DIS: hep-ph/0604128 – Sivers function in Drell-Yan is expected to have a sign opposite to that in DIS • test of QCD between e+p data and p+p data 2007年 10月19日(金) 48
Polarized Drell-Yan • AN measurement 4 < M + - < 5 Ge. V integrated over q. T Theory calculation by Ji, Qiu, Vogelsang and Yuan based on Sivers function fit of HERMES data (Vogelsang and Yuan: PRD 72, 054028 (2005)) 2007年 10月19日(金) 1000 fb-1 (120 -day run), 75% polarization, no dilution factor 49
Polarized Drell-Yan • ATT measurement – h 1(x): transversity • SSA measurement, sin( + S) term – h 1(x): transversity – h 1 (1)(x): Boer-Mulders function (1 st moment of) 2007年 10月19日(金) 50
Unpolarized Drell-Yan • Boer-Mulders function h 1 (x, k. T 2) – angular distribution of unpolarized Drell-Yan – correlation between transverse quark spin and quark transverse momentum 2007年 10月19日(金) 51
Unpolarized Drell-Yan • Boer-Mulders function by unpol. Drell-Yan – Lam-Tung relation • reflect the spin-1/2 nature of quarks – violation of the Lam-Tung relation suggests nonperturbative origin With Boer-Mulders function h 1┴: ν(π-W µ+µ-X)~valence h 1┴(π)*valence h 1┴(p) ν(pd µ+µ-X)~valence h 1┴(p)*sea h 1┴(p) L. Y. Zhu, J. C. Peng, P. Reimer et al. , hep-ex/0609005 2007年 10月19日(金) 52
Towards the goal • 30 Ge. V 50 Ge. V • unpolarized target polarized beam – polarized beam study by BNL & KEK groups – possible locations of partial snakes in MR First 30% snake 2007年 10月19日(金) Second 30% snake 53
Polarized proton acceleration at J-PARC – 50 Ge. V polarized protons for slow extracted beam primary fixed target experiments – low intensity (~ 1012 ppp), low emittance (10 mm mrad) beams p. C CNI Polarimeter Extracted Beam Polarimeter - Pol. H Source Rf Dipole 180/400 Me. V Polarimeter 25 -30% Helical Partial Siberian Snakes Thomas Roser (BNL), et al. 2007年 10月19日(金) 54
Physics at 30 Ge. V • J/ – gluon fusion or quark-pair annihilation – quark-pair annihilation dominant • must be confirmed experimentally… • similar physics topics as Drell-Yan process calculations by color-evaporation model eq J/ 2007年 10月19日(金) 55
Physics at 30 Ge. V • SSA measurement of open charm production J-PARC: Elab = 50 Ge. V – no single-spin transfer to the final state – sensitive to initial state effect: Sivers effect – collider energies: gluonfusion dominant • sensitive to gluon Sivers RHIC: s = 200 Ge. V effect – fixed-target energies: quarkpair annihilation dominant • sinsitive to quark Sivers effect M. Anselmino, U. D’Alesio, F. Murgia, et al. 2007年 10月19日(金) 56
SSA measurements of neutron – large asymmetry found at RHIC – production mechanism of neutron • one-pion exchange dominant – spin flip • figures for study in DIS exps. (HERA), please replace virtual photon with proton to apply them for pp reaction – asymmetry measurement • sensitive to interference between spin-flip term (one-pion exchange) and non-spinflip term (other reggeon exchanges) – relation to the meson-cloud model? – neutron-tagged measurement of Drell-Yan? • production rate • asymmetry measurement 2007年 10月19日(金) 57
まとめ • J-PARC dimuon 実験のスピン物理メニュー – 縦偏極 ALL of Drell-Yan • sea-quark 偏極のフレーバー非対称性 – 横偏極 AN of Drell-Yan • Sivers関数(sin-term) • transversity分布関数 & Boer-Mulders関数(cos-term) – 横偏極 ATT of Drell-Yan • transversity分布関数 – その他(30 -Ge. V) • J/ : Drell-Yan と同様のメニュー? • AN of open charm: Sivers関数 • neutron-tagged Drell-Yan 2007年 10月19日(金) 58
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