Contalbrigo Marco INFN Ferrara Symposium on Hadronic Structure Physics April 14, 2010 University of Glasgow

Spin degrees of freedom can explain otherwise surprising phenomena and bring new insights into nuclear matter structure e p → e p PRC 68, (2003) xFxF The spin degree of freedom Fundamental: do not neglect it !! 2 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

xFxF √s = GeV pBe→   X Hep-ph p  p→  X p T < 2 GeV/c √s = 20 GeV xFxF E704 Fermilab PLB 264, 462 (1991) √s = 200 GeV hep-ex xFxF STAR BNL NA10 E866 E615 Drell-Yan Hep-ex The spin surprising phenomenology 3 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo  ~

The spin structure of the nucleon Describe the complex nucleon structure in terms of partonic degrees of freedom of QCD Proton’s spin JqJq Understanding of the orbital motion of quarks is crucial! Important testing ground for QCD Phys Lett B647 (2007) 8-17 Latest news from Deep Inelastic Scattering (DIS)  =0.33±0.03 Phys. Rev. D 75 (2007) JgJg  G small at 0.02<x<0.3 From DIS and pp scattering e-print Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

The real experience: 3D ! 5 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

PDFs f p u (x),… TMD PDFs: f p u (x,k T ),… d2kTd2kT  =0,t=0 W p q (x,k T,r) “Mother” Wigner distributions d3rd3r d2kTd2kT Measure momentum transfer to target Direct info about spatial distributions Measure momentum transfer to quark Direct info about momentum distributions Probability to find a quark q in a nucleon P with a certain polarization in a position r & momentum k (FT) GPDs: H p u (x, ,t), … 6 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo p T < 2 GeV/c √s = 20 GeV xFxF ANAN Proton spin puzzle SSA J q =1/2  + L q = lim dx x [H(x, ,t) + E(x, ,t)] t  0 1

7 ┴┴ ┴ ┴ ┴ g 1L h1h1 Fragmentation Functions (FF) Distribution Functions (DF) Interference between wave functions with different angular momenta: contains infos about parton orbital angular momenta Testing QCD at the amplitude level Off-diagonal elements are important objects: 3D description in momentum space PRD 78 (2008) Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo Strict prediction of QCD ! sign change between DY and SIDIS universality of TMDs

┴┴ ┴ ┴ ┴ Distribution Functions (DF) SIVERS Quark orbital angular momentum BOER-MULDERS Spin orbit effect 8 3-momentum space Impact parameter space anti-green remnant green quark GPD EGPD E T +2H T ~ Deformations by i.e. Sivers: spin-orbit correlations with same matrix element of anomalus magnetic moment, and GPD E Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

X Inclusive SFs (x,Q 2 ) Structure functions (unpolarized, helicity) Sum over quark charges 9 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo Semi-inclusive Parton distributions Flavor sensitivity PDFs (x,z,Q 2 ) Transverse momentum dependent parton distri. Spin-Orbit effects TMDs (x,z,P h,Q 2 ) T Semi-inclusive Rich and Involved phenomenology !!

Contalbrigo Marco Consiglio di Sezione 1 luglio 2009 Great success, but exploiting only leptonic degrees of freedom. 10 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

12 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo 180 mrad “Natural” muon beam polarization: GeV muons from pion decays low beam currents I  1 pA    J=0 Solid state target operated in frozen spin mode high-mass cryogenic target N  nucleons/cm 2 small fraction of polarizable nucleons NH 3,ND 3, 6 LiD 2007: NH 3 (polarised protons) dilution factor f = 0.14 polarization P T = 90% : 6 LiD (polarised deuteron) dilution factor f = 0.38 polarization P T = 50% Polarization switching tsakes time done few times in a year

self-polarising ~ 53 ± 2.5 % 27.5 GeV (e  /e  ) 1 H → ~ 85 ±3.8 % 2 H → ~ 84 ±3.5 % 1 H ~ 74 ±4.2 % 13 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo Pure nuclear-polarised H,D atomic gaseous target ms polarization switching at 90s time intervals L ~ O(10 31 ) cm -2 s -1 Self-polarising e + /e - beam: Sokolov-Ternov effect

Pros 1.Small field (∫Bdl~ Tm) 2.Small dilution (fraction of events from polarized material) 3.Less radiation length 4.Less nuclear background (no nuclear attenuation) 5.Wider acceptance much better FOM, especially for deuteron 6.H and D may be independently polarized Cons 1.HD target is highly complex and there is a need for redundancy due to the very long polarizing times (months). 1.Need to demonstrate that the target can remain polarized for long periods with an electron beam with currents of order of 1-2 nA 2.Additional shielding of Moller electrons necessary (use minitorus) Heat extraction is accomplished with thin aluminum wires running through the target (can operate at T~ mK) HD-Ice target at ~ 1-2nA NH 3 at ~ 5-10 nA HD-Ice target vs std nuclear targets HD-Ice JLab 14 P= 95 % H, 70 % D Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

May 2006 RHIC pC Polarimeters Absolute Polarimeter (H  jet) 200 MeV Polarimeter Helical Partial Siberian Snake Partial Snake Spin Rotators (longitudinal polarization) Siberian Snakes AGS Pol. H - Source PHOBOS PHENIX STAR BRAHMS LINAC BOOSTER E p = 100 GeV Siberian Snakes suppress depolarizing resonances during accel. AGS: variable twist helical dipoles (3T), 2.6 m RHIC : full twist helical dipoles (4T), 2.4 m 15 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

16 P beam polarization Q target polarization k || beam direction σ tot = σ 0 + σ 1 ·P·Q + σ 2 ·(P·k)(Q·k) Model A: T. Hippchen et al., Phys. Rev. C 44, 1323 (1991). Model OBEPF: J. Haidenbauer, K. Holinde, A.W. Thomas, Phys. Rev. C 45, 952 (1992). Model D: V. Mull, K. Holinde, Phys. Rev. C 51, 2360 (1995). → Spin filtering works for protons F. Rathmann et al., PRL 71, 1379 (1993) Polarization buildup process quantitatively understood D. Oellers et al., PLB 674 (2009) 269 Xsec and spin correlations to be measured The spin filtering Polarized antiproton beams polarized valence antiquarks Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

17 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo COSY AD Longitudinal Strong dependence on the ring characteristics: vacuum, acceptance Model A: T. Hippchen et al., Phys. Rev. C 44, 1323 (1991) TSR: T = 23 MeV, Ψ acc = 4.4 mrad Longitudinal Transversel

e+e- annihilation: FFs Not zero Collins & IFF Drell-Yan: PDFs Not zero Boer-Mulders SIDIS: PDFs x FFs Not zero Sivers Not zero h 1, Collins & IFF Non zero Boer-Mulders ……. pp reactions: PDFs x FFs Strong SSA at large x F e + e - hhX RICH CLEAN Hadron probe Lepton probe 19 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo ep e’hX hp  X pp  hX

20 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo ┴┴ ┴ ┴ ┴ g 1L h1h1 Distribution Functions (DF) Fragmentation Functions (FF) A. Airapetian et al, Phys. Rev. Lett. 94 (2005) : First evidence from HERMES SIDIS on proton Non-zero transversity !! Non-zero Collins function !! SIDIS: ep e’hX

21 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo 4x4 z 1 z 2 binning      e-e- e+e+ HERMES & COMPASS: BELLE:

22 Tensor charge M. Anselmino et al hep-ph: M. Wakamatsu hep-ph: Collins fragmentation function Transversity Positivity bound Soffer’ bound Helicity distribution Evolution ? 2 k T dependence ? 1 Gaussian alsatz Standard evolution Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

23 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

Non perturbative contribution P T (GeV/c) ┴┴ ┴ ┴ ┴ g 1L h1h1 Distribution Functions (DF) Fragmentation Functions (FF) 24 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo Predicted since 1978 by Cahn Non-zero intrinsic k T !! EMC M. Arneodo et al, Z Physics C34 (1987) 277 SIDIS: ep e’hX

25 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo EMC (1987) SIDIS: ep e’hX hp  X Drell-Yan: NA10 E866 E615 Small in the sea region ?! ┴┴ ┴ ┴ ┴ g 1L h1h1 Distribution Functions (DF) Fragmentation Functions (FF)

26 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo Stat err only

27 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo preliminary Sub-leading twist ! Sign of non-zero BM ? Stat err only Higher twists ? 3

┴┴ ┴ ┴ ┴ g 1L h1h1 Distribution Functions (DF) Fragmentation Functions (FF) 28 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo A. Airapetian et al, Phys. Rev. Lett. 94 (2005) : First evidence from HERMES SIDIS on proton Non-zero Sivers function !! SIDIS: ep e’hX

COMPASS on deuteron: 29 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo HERMES on proton:

30 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo HERMES on proton: COMPASS on deuteron: M. Anselmino et al, Eur. Phys. J. A39 (2009) 89 Not negligible sea contribution !

31 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo M. Anselmino et al, Eur. Phys. J. A39 (2009) 89 Flavor decomposition ? 4 Not negligible sea contribution ! pp RHIC: √s = 200 GeV hep-ex xFxF Universality ? 5

x x □ COMPASS 2010 h +, projection ■ COMPASS h +, Transversity 2008 HERMES  +, DIS2007 a factor of 3 with respect to the released COMPASS data x 32 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

Executive summary TMDs are a new class of phenomena providing novel insights into the rich nuclear structure Limited knowledge on transverse momentum dependences Flavor decomposition often missing Evolution properties to be defined Role of the higher twist to be quantified Universality Fundamental test of QCD in the spin sector Non-zero results from DIS experiments provide promises but also open questions Crucial: completeness All reactions, flavor tagging and multi-dimensional extraction in all variables (x,z,Q 2,P T ) to have all dependencies resolved Still incomplete phenomenology is asking for new inputs 33 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

e+e- annihilation: FFs k T dependence Evolution Drell-Yan: PDFs Universality (sign change) Flavor decomposition SIDIS: PDFs x FFs Multidimensional analysis factorize PDFs and FFs investigate higher-twists study perturbative transition flavor decomposition pp reactions: PDFs (x FFs) Factorization Universality RICH CLEAN Hadron probe Lepton probe 35 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo e + e - hhX ep e’hX hp  X pp  hX

Contalbrigo Marco Consiglio di Sezione 1 luglio Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo Belle Detector Hadrons in opposite hemispheres: Dependence on transverse momentum FFs for various hadron: 2 , kaons, ( , …  ) Scale dependence: look for different c.m. energies Only one experiment: validation needed !

a=  b=  RL:RL: a=  b=  R UL : Run1-Run6 Off Peak uds events R UL /R L a=  b=  GeV e + e -  qqbar (q=u,d,s) Contalbrigo Marco Consiglio di Sezione 1 luglio Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo Babar Detector Belle Detector Different detector: systematic check ! Double Ratio MC: thrust reference frame Qt<4.3

Contalbrigo Marco Consiglio di Sezione 1 luglio Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo Babar Detector Belle Detector Different detector: systematic check !

ParameterRequirementComment Luminosity (top-up mode)10 36 cm -2 s  (4S) Integrated luminosity75 ab -1 Based on a “New Snowmass Year” of 1.5 x 10 7 seconds (PEP-II experience-based) CM energy range t threshold to  (5S) Minimum boost  = 0.28 (4x7 GeV) 1 cm beampipe radius. First measurement at 1.5 cm e - Polarization60-85%Enables t CP and T violation studies, measurement of t g-2 and improves sensitivity to lepton flavor-violating decays. Detailed simulation, needed to ascertain a more precise requirement, are in progress. 39 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo Probe TMDs evolution

e+e- annihilation: FFs k T dependence Evolution Drell-Yan: PDFs Universality (sign change) Flavor decomposition SIDIS: PDFs x FFs Multidimensional analysis factorize PDFs and FFs investigate higher-twists study perturbative transition flavor decomposition pp reactions: PDFs (x FFs) Factorization Universality RICH CLEAN Hadron probe Lepton probe 40 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo e + e - hhX ep e’hX hp  X pp  hX

x vs z z vs P h ┴ 41 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

Limit defined by luminosity Different Q 2 for same x range EIC Resonance region 42 The SIDIS landscape Valence Complementary experiments Sea Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

6 GeV CEBAF CHL-2 Upgrade magnets and power supplies 12 GeV CEBAF Enhance equipment in existing halls add Hall D (and beam line) : Construction (funded at 99%) May GeV Accelerator Shutdown starts May 2013 Accelerator Commissioning starts October 2013 Hall Commissioning starts Pre-Ops (beam commissioning) 43 Beam current 90  A Beam polarization 85 % Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

Perturbative region Collinear factorization Non-perturbative TMD factorization Unpolarized CLAS12 44 Band: Phys Rev D Boer-Mulders from DY data Collins from chiral limit Line: Phys Rev D Boer-Mulders from Sivers Collins from e+e- data kaon s -1 cm -2 LH 2 LD 2 targets Boer-Mulders spin-orbit effect Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

proton PTPT M.Anselmino et al hep-ph/ Phys.Rev.D74:074015,2006  0 2 =0.25GeV 2  D 2 =0.2GeV 2 Helicity dependence of k T - distribution of quarks Polarized CLAS s -1 cm -2 NH 3 and ND 3 target P beam = 85 % In the perturbative limit 1/P T behavior expected A LU ~ 1/Q (Twist-3) Measurements of kinematic (x,Q 2,z,P T ) will probe HT distribution functions Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

Collins CLAS s -1 cm -2 HD-ice (P=85%) Curves fom A.V. Efremov et al PRD76:094025,2006 Tensor charge M. Anselmino et al hep-ph: M. Wakamatsu hep-ph: Study A UT at large x (valence) where models are mostly unconstrained x Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

GeV protons 3 – 9 GeV electrons √s ~ GeV L~ cm -2 s GeV protons 3 – 10 GeV electrons √s ~ GeV L~ cm -2 s -1 e,p polarization greater than 70 % 47 High luminosity is better than high-energy: Sudakov suppression (soft gluon radiation) Electron Ion Collider Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

EIC measurements at small x will pin down sea contributions to Sivers function S. ArnoldS. Arnold et al arXiv: M. AnselminoM. Anselmino et al arXiv: CLAS12 & EIC 48 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

e+e- annihilation: FFs k T dependence Evolution Drell-Yan: PDFs Universality (sign change) Flavor decomposition SIDIS: PDFs x FFs Multidimensional analysis factorize PDFs and FFs investigate higher-twists study perturbative transition flavor decomposition pp reactions: PDFs (x FFs) Factorization Universality RICH CLEAN Hadron probe Lepton probe 49 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo e + e - hhX ep e’hX hp  X pp  hX

50 Cross-section is consistent with NLO pQCD calculations pp  >  0 X:PRD76, (2007) |η|<0.35 √s=200 GeV High rate Limited acceptance Forward muon detector Large acceptance Limited rate Forward colarimeters Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

Sivers from SIDIS data PRD70 (2004) Twist-3 correlators and collinear factorization PRD74 (2006)  An at positive x F grows with increasing x F  x F dependence matches theoretical model expectations qualitatively  But some surprise emerges… p T dependence asymmetries for different hadrons 51 √s=200 GeV PRL 101 (2008) Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

52 Left-Right analyzing power for inclusive meson production Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

53 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

10 4 useable forward photon + jet coincidences are expected in a 30 pb -1 data sample with 60% beam polarization 54 “Jet shape” in data matches simulation well energy distribution within jet-like objects in the FMS as a function of distance from the jet axis. No fragmentation No Collins effect Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

55 arXiv: Z.B. Kang, J.W. Qui PRL 103 (2009) SSA survives the dilution due to W decay Flavor separation ! Z’s as clean theoretically as DY Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

e+e- annihilation: FFs k T dependence Evolution Drell-Yan: PDFs Universality (sign change) Flavor decomposition SIDIS: PDFs x FFs Multidimensional analysis factorize PDFs and FFs investigate higher-twists study perturbative k T transition flavor decomposition pp reactions: PDFs (x FFs) Factorization Universality RICH CLEAN Hadron probe Lepton probe 56 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo e + e - hhX ep e’hX hp  X pp  hX

NA10 E866 E615 pp, pd Fermilab 57 Sensitive to relative sign of h 1 u vs h 1 d E866 pQCD PRL 102 (2009) PRD 74 (2006) PLB 656 (2007) 74 E906: Data taking starts this summer Precise measurement of Boer-Mulders Extends E866 measurements at 120 GeV xsec scales as 1/s background scales as s Systematic uncertainty ~1% in cross section ratio.  ~ Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

√s = 200 GeV W. Vogelsang et al., PRD72 (2005) e  e   |  |<0.35      1.2<|  |<2.2 pp RHIC 58 Need detector upgrades to distinguish DY and heavy flavor J/  as benchmark channel M  * >4 GeV x  >0.3 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

 p CERN Under study is the feasibility of the measurement: Proposal:  − beam of 160 GeV/c on a NH 3 target  Hadron absorber  Dimuon trigger  Radiation conditions h beam test2 years at L= cm -2 s -1 A UT Based on pion PDFs xFxF Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

s=45 GeV 2 s=210 GeV 2 s=45 GeV 2 s=210 GeV 2 Cross-section Asymmetry H. Shimizu et al., hep-ph/ V. Barone et al., in preparation QCD corrections might be very large at smaller values of M, for cross-sections, not for A TT : K-factor almost spin-independent h 1 from p-p FAIR 60 - Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo PANDA: unpolarized target (s=30 GeV 2 ) PAX: polarized collider (s=200 GeV 2 )

Similar predictions by Efremov et al., Eur. Phys. J. C35, 207 (2004) Anselmino et al. PLB 594,97 (2004) 1year run: 10 % precision on the h 1u (x) in the valence region P p =10% P p =30% PAX :    s=x 1 x 2 ~ valence quarks (A TT large ~ ) h 1 from p-p FAIR 61 u-dominance |h 1u |>|h 1d | - Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo PANDA: unpolarized target (s=30 GeV 2 ) PAX: polarized collider (s=200 GeV 2 )

IHEP 62 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

63 pp pp ep pp ee Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo You are welcome to join !

64 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

65 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo QCD prediction: f 1T  (x) SIDIS = - f 1T  (x) DY anti-green remnant green quark anti-green anti-quark anti-green remnant green quark q  qq  qqq    l+ l-qq    l+ l- anti-lensing 

Collins moment Sivers moment Asymmetries and moments [angle and moments definitions according to Trento conventions] h h h h 66 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

67 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo

68 Hadronic Structure Physics, 14 th April 2010, Glasgow University M. Contalbrigo