Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS JLab with CLAS  6 GeV  CLAS12 and TMDs 12 GeV  Conclusions May 18-21, 2010 TJNAF -Newport News, Virginia USA

Introduction Nucleon is a complex object Our goal is:  Study its STRUCTURE  3D image (coord. & mom.)  Spin origin  Flavor content  Understand CONFINEMENT Transverse Momentum dependent parton Distribution functions (TMDs) are relevant for all these issues

SIDIS experiments and SSAs Inclusive DIS experiments - 2D image (collinear approx.) - unable to account for all the nucleon spin k’, E’ k, E DF  Observable are Single Spin Asymmetry (SSAs) which are due to correlations between transverse momentum of quarks ( k  ) and the spin of the quark/nucleon moments of  s Semi-Inclusive DIS experiments - 3D image in momentum space - Access quark orbital momentum Lq X h FF ‘

Jefferson Lab and CLAS Beam: continuous Energy: GeV Current: 0.1nA  A Polarization: 75-85% A B C 20 cryomodules e p  e’ h X 1.high intensity beam with high polarization 2.polarized targets 3.high acceptance for the hadron CLAS at JLab perfectly matches all this requirements Lumi ~10 34 cm -2 sec -1CLAS e-e- Data in 2011? Data taken in 2001/2005/2009

Experimental configuration for unpolarized/long.polarized target Inner Calorimeter (424 PbWO 4 crystals) to detect high energy photons at forward lab angles. IC Polarized target (NH3/ND3) Pol. NH 3, ND 3 targets =0.75, =0.3 Longitudinal polarization  Experimental configuration

ep  e’   X  DIS kinematics: Q 2 >1 GeV 2, W 2 >4 GeV 2, y<0.85 1)Longitudinally Polarized NH3/ND3 (no IC, ~5 days) )Longitudinally Polarized NH3/ND3 with IC 60 days )Unpolarized H with IC ~60 days )Transversely Polarized HD-Ice (no IC, 25 days)2011 (?) A UL, A LL : arXiv: Submitted to PRL New data under analysis Experiment E  0 BSA Analysis completed Analysis note under coll. review Experiment in preparation Q2Q2 SIDIS with 6 GeV

 CLAS program: extraction of leading twist and higher twist TMDs  quark-gluon-quark correlations responsible for azimuthal moments of h.t.  0 BSA U U UU  0/+/- TSA L L LL P T -dependence Pion SSA with unpol./long. Polarized target

Transversely polarized quarks in a longitudinally polarized nucleon H. Avakian et al. arXiv: ~5 days data taking A UL  over the full kinematics Fitting function: p 1 sin  +p 2 sin2  ++ p 1 = 0.047±0.010 p 2 =-0.042±0.010 p 1 = 0.046±0.016 p 2 =-0.060±0.016 p 1 = 0.059±0.018 p 2 =-0.010±0.019 No indication of Collins effect for  0 Non-zero negative asymmetry for  +/- e p  e’   X ~10% of E data Longitudinal pol. Target Kotzinian-Mulders asymmetry

H. Avakian et al. arXiv: curves,  QSM from Efremov et al Total good events accumulated on proton with CLAS in 3 months ~ 10 times statistics accumulated by HERMES in 2 years Analysis Topics :  +/-/0 A UL (sin2  ), A LL, A LU (sin  )  +/- A UL (sin2  ) Projected results for Exp. E Longitudinal pol. Target Kotzinian-Mulders asymmetry

Anselmino et. al PRD74,074015(2006) Different width of TMDs of quarks with different flavor and polarizations R=0.40 R=0.68 R=1.0 f 1 =0.25 GeV 2 Data shows slight preference for R <  H. Avakian et al. arXiv: ++ 00  - New experiment with 10 times more data will study the P T -dependence for different quark helicities and flavors for bins in x Projected results for Exp. E Longitudinal pol. Target: A 1 -P T dependence

e p  e’   X BSA ~ sin  insensitive to other harmonics BSA: Asymmetry extraction and fitting for  0

M Aghasyan, LNF-INFN Drop with P T below 1 GeV/c A LU in agreement with HERMES data M Aghasyan, LNF-INFN Comparable BSA for  0 and  + Small Collins type contributions for  + ? M Aghasyan, LNF-INFN Main contribution?  0 BSA Asymmetry results

 Target used by LEGS at BNL with photon beam Pros Small field (∫Bdl~ Tm) Small dilution factor Less radiation length Less nuclear background Wider acceptance much better FOM, especially for deuteron Cons HD target is highly complex and there is a need for redundancy due to the very long polarizing times (months). Need to demonstrate that the target can remain polarized for long periods with an electron beam with currents of order of 1-2 nA HDice installation in the HallJanuary 2011 photon run with HD-iceMarch 2011 test run with e-end of Apr 2011 physics run with e-t.b.d.  The target is now at Jlab and all equipment moved to the new HDice lab Transversely polarized HD-ice target Tentative schedule

Sivers Collins Sivers TMD transversity TMD Collins FF pretzelosity TMD Collins FF Projected results for 30 days of CLAS at 6 GeV in 2011 ( P T =75% L= cm -2 s -1 ) CLAS will provide a superior measurements of Sivers asymmetry at large x, where the effect is large and models unconstrained by previous measurements. curves from Yuan, Efremov,Collins TMDs with transversly polarized target

Hall A Beam: 6 GeV, 15  A (target limit) Neutron Target: High pressure polarized 3 He, 50 mg/cm 2, Pol. ~ 60% Hadron Detection: HRS Left P h = 2.4 GeV/c,  /K ID Kinematic Region = 2.2 GeV 2, x = 0.13  0.4, z ~ 0.5 e-e-  +/- 1 month data taking: statistical errors comparable to HERMES(3 years)/COMPASS(2 years) Analysis underway TMDs on a transversely pol. neutron in HALL A

 Transverse degrees of freedom led to a bunch of new, more complex, distribution and fragmentation functions  Unpolarized and polarized data from different Laboratories are giving a first look at these new functions  A new generation of experiments is necessary to fully exploit the properties of TMDs, with - wide kinematic coverage - high luminosity - high polarization - high capability of final hadron separation Summary of experimental results

CHL- 2 Beam Current: 90 µA Max Pass energy: 2.2 GeV Max Enery Hall A,B,C: 11 GeV May GeV Accelerator Shutdown starts May 2013 Accelerator Commissioning starts Pre-Ops (beam commissioning) Solenoid 5T DC R1, R2, R3 LTCC HTCC FTOF PCAL EC CLAS12 L = cm -2 s -1 Primary goal of experiments using CLAS12: study of the internal nucleon dynamics by accessing GPDs & TMDs  detector tuned for studies of exclusive and semi-inclusive reactions in a wide kinematic range.  Large acceptance detector and high luminosity capabilities 12 GeV and CLAS12

1 GeV 2 Study of high x B domain requires high luminosity CTEQ5M parton distribution x f(x,Q) x Q=5 GeV We are here! Kinematic suppression small cross section 12 GeV Kinematical coverage

E : E : Pion SIDIS E : E : Kaon SIDIS E : E : Pion SIDIS E : E : Kaon SIDIS LOI : LOI : Pion SIDIS LOI : LOI : Kaon SIDIS PAC approved experiments & LoI N q U L T  Complete program of TMDs studies for pions and kaons  Kaon measurements crucial for a better understanding of the TMDs “kaon puzzle”  Kaon SIDIS program requires an upgrade of the CLAS12 detector PID  RICH detector to replace LTCC Project under development TMDs 12 GeV in Hall B

Kaon TMDs 12 GeV in Hall B K+K+ K-K- -- ++ K + ampl. >  + ampl. Unespected from u-quark dominance! How large can the effect of s quarks be? HERMES coll. PRL 103 (2009)  /K CLAS12 will provide a more detailed knowledge of Sivers effect ep  e’K + X S.Arnold et al M. Anselmino et al

 Measurements of azimuthal dependences of single and double spin asymmetries indicate that correlations between spin and transverse motion of quarks may be significant  CLAS in Hall B at Jlab is playing a major role in these studies  The new CLAS experiment with longitudinally polarized NH3 and ND3 targets provides superior sample of events allowing multidimensional binning to study: - SSAs for  and  in SIDIS - Higher Twists and quark-gluon correlations - Double spin asymmetries and flavor decomposition of helicity dist.  Studies of the spin-structure of the nucleon is one of the main driving forces behind the upgrade of Jefferson Lab  JLab12 with wide kinematic coverage, high luminosity, high polarization is essential for high precision measurements of 3D PDFs in the valence region Conclusions and Outlook

Pretzelosity with CLAS12 u quark k  =0 k  =2.0 GeV CLAS12 will provide first pretzelosity measurement in the valence region for Kaons and pions. B. Pasquini et al. Phys.Rev.D78:034025, Avakian et al., PRD78, Exciting relation: (in bag & spectator model) ‘measure’ of relativistic effects  Role of pretzelosity investigated to produce a non spherical shape of the nucleon B. Pasquini et al. Phys.Rev.D78:034025,2008