H. Avakian, POETIC, Sep 23 1 Harut Avakian (JLab) Di-hadron measurements at JLab Measurements of hadron pair production in SIDIS Studies of the transversity and Sivers distributions Studies of quark-gluon correlations B2B SIDIS Summary POETIC V New Haven, CT, 22nd -26th September 2014

H. Avakian, POETIC, Sep 23 2 QCD: from testing to understanding Testing stage: pQCD predictions, observables in the kinematics where theory predictions are easier to get (higher energies, 1D picture, leading twist, current fragmentation, IMF) Understanding stage: non-perturbative QCD, strong interactions, observables in the kinematics where most of the data is available (all energies, quark- gluon correlations, orbital motion) nucleon in 3D quark-gluon correlations spin-orbit correlations evolution, factorization, entanglement hadronization parton distributions strong interactions & quark gluon dynamics spectroscopy, excited states 0h 1h SIDIS 2h production in SIDIS provides access to correlations inaccessible in simple SIDIS

H. Avakian, POETIC, Sep 23 3 Transversity distribution from 1h SIDIS LCCQM spectator model Soffer bound M. Anselmino et al., (2009) A. Bacchetta et al.(2008) B. Pasquini et al(2007) A model independent TMD flavor decomposition procedure is required to estimate the systematic error of extraction of transversity TMD.

Dihadron production H. Avakian, POETIC, Sep 23 4 h1h1 h2h2 Dihadron productions offers exciting possibility to access transversity distribution as we deal with the product of functions instead of convolution BNL arXiv: Factorization proven Evolution known Extracted at BELLE for  pairs, planned for  K pairs R T ≅ transverse to  * component of the transverse to pair total momentum, P, component of R

Dihadron cross sections with transverse target H. Avakian, POETIC, Sep 23 5 Similar to single hadron SIDIS with  R   h

H. Avakian, POETIC, Sep 23 6 Accessing transversity from target SSA Target spin asymmetry can be presented as a flavor sum of products of PDF and FF. SSA A UT on proton provides access to transversity flavor sum (need interference FFs) Leading twist Use Belle measurement

7 JLab Experimental Halls Polarized target IC Hall B 424 PbWO 4 ~87% ~8% ~1.5% H. Avakian, POETIC, Sep 23

8 Scattering of 5.7 GeV electrons off polarized proton and deuteron targets SIDIS with JLab at 6 GeV  DIS kinematics, Q 2 >1 GeV 2, W 2 >4 GeV 2, y<0.85  0.4>z>0.7, M X 2 >2 GeV 2 2 eXeX Large acceptance and full coverage in azimuthal angle  allows di-hadron measurements in DIS kinematics

Dihadron simulations with GeV H. Avakian, POETIC, Sep 23 9 Reasonable agreement with LUND-MC already at 6 GeV

H. Avakian, POETIC, Sep Dihadron asymmetries from CLAS SIDIS (TMDs) DVMP (GPDs) Dihadron double spin asymmetry measured at 6 GeV consistent with DIS CLAS Preliminary S. Anefalos Pereira

11 Quark-gluon correlations: Models vs Lattice Models agree on a large e/f 1 -> large beam SSA Lattice results for u-d can be directly compared to models and data. H. Avakian, POETIC, Sep 23 Musch et al, arXiv: CLAS/HERMES Force on the active quark right after scattering (Burkardt)

H. Avakian, POETIC, Sep Dihadron beam SSA with CLAS Dihadron asymmetries measured at 6 GeV by CLAS provide access to Twist-3 e CLAS preliminary e1f (5.5 GeV) e1dvcs (5.9 GeV) S.Pisano CLAS preliminary A. Courtoy

H. Avakian, POETIC, Sep Dihadron production at JLAB12 Use the clasDIS (LUND based) generator + FASTMC to study   pairs x F - momentum in the CM frame Dihadron sample defined by SIDIS cuts+x F >0 (CFR) for both hadrons   Wide angular coverage is important SoLIDCLAS12

H. Avakian, POETIC, Sep Dihadron production with CLAS12 CLAS12 will provide precision measurements of target spin asymmetries in a wide range of x and Q 2 in dihadron pair production in SIDIS .1 Missing mass of  system Invariant mass of K  system

H. Avakian, POETIC, Sep Accessing transversity in dihadron production at JLab Measurements with polarized protons Measurements with polarized neutrons CLAS12 SoLID

H. Avakian, POETIC, Sep Studies of Quark-gluon correlations with CLAS12 30 days of NH3 CLAS12 will provide precision measurements of longitudinal beam and target single-spin asymmetries in dihadron pair production in SIDIS 54 days of unpolarized proton

H. Avakian, POETIC, Sep Accessing Sivers TMD in dihadron production at JLab Measurements with polarized CLAS12 Measurements with polarized Measurements with EIC A. Kotzinian, H. H. Matevosyan, and A. W. Thomas, Phys.Rev.Lett. 113, (2014), After integration over the azimuthal angle of total transverse momentum The asymmetry as a function of the relative transverse momentum 1 st harmonic of the cos(  T -  R )  R ≠0 can be ensured, by choosing asymmetric cuts on the minimum values of z1 and z2. SOLID-predicted

Target fragmentation region:  production polarization tranfer coefficient 60 days of CLAS12 18 H. Avakian, POETIC, Sep 23 probability to produce the hadron h when a quark q is struck in a proton target Measurements of fracture functions opens a new in studies of the structure of the nucleon in general and correlations between current and target fragmentation in particular Large acceptance of CLAS12 and EIC provide a unique possibility to study the nucleon structure in target fragmentation region and correlations of target and current fragmentation regions

H. Avakian, POETIC, Sep Back-to-back hadron (b2b) production in SIDIS The beam–spin asymmetry appears, at leading twist and low transverse momenta, in the deep inelastic inclusive lepto- production of two hadrons, one in the target fragmentation region and one in the current fragmentation region. M. Anselmino, V. Barone and A. Kotzinian, Physics Letters B 713 (2012) Back-to-back hadron production in SIDIS would allow: study SSAs not accessible in SIDIS at leading twist measure fracture functions control the flavor content of the final state hadron in current fragmentation (detecting the target hadron) study correlations in target vs current and access factorization breaking effects (similar to pp case) access quark short-range correlations and  SB (Schweitzer et al)... P2P2 P1P1

H. Avakian, POETIC, Sep Summary Study interference effects in hadronization Provide an independent measurement of the transversity distribution Provide independent measurements of Sivers distribution Study quark-gluon correlations Access correlations of target and current fragmentation  The large acceptances of the CLAS12 and SOLID at JLab provide unique possibility to study hadron pairs in electroproduction  Large acceptance, high Q 2, high multiplicities, separation of target and current fragmentation at EIC will significantly enhance the role of di-hadrons in studies of non peturbative QCD. Precision measurement of hadron (K   pairs in SIDIS provide qualitatively new possibilities to:  Significant SSA observed in hadron pair production in SIDIS

H. Avakian, POETIC, Sep Support slides….

Definitions of  R in dihadron production H. Avakian, POETIC, Sep the transverse to g*-direction component of the transverse to pair total momentum, P, component of R transverse momenta acquired in fragmentation

H. Avakian, POETIC, Sep Dihadron A LU with CLAS12 54 days of unpolarized proton and deuteron running will allow precision measurement of HT distribution e bag model spectator model

EIC simulations with mPYTHIA H. Avakian, POETIC, Sep SSAs for  + and K+ are large, while those for  - and K- relatively small. H. Matevosyan SSAs for  + drops with energy 1-hadron 2-hadron

H. Avakian, POETIC, Sep Transverse force on the polarized quarks Quark polarized in the x-direction with k T in the y-direction Force on the active quark right after scattering (t=0) Interpreting HT (quark-gluon-quark correlations) as force on the quarks (Burkardt hep-ph: ) pion-nucleon  -term

A LU in b2b SIDIS with 5.5 GeV H. Avakian (JLab), TM-2014, Sep Preliminary results for a significant ALU asymmetry from CLAS with π+ produced in CFR and π− – in TFR.

 production in the target fragmentation region (LEPTO 4x60) direct  hyperon decay  e’e’ p e Λ  H. Avakian (JLab), TM-2014, Sep angular distributions of protons and ani-protons Most of the direct Lambdas in the target fragmenatation region anti-  X (x10)  X 27

correlations between target and current H. Avakian (JLab), TM-2014, Sep

H. Avakian, POETIC, Sep 23 Dihadron Fragmentation Evolution effects small for DiFF/D 1 DiFF represent the easiest way to measure the polarization of a fragmenting quark DiFF contain information on interferences between different channels (e.g., rho and continuum), which cannot be encoded in MC generators based on the Lund model Significant DiFF published by BELLE A.Courtoy 29

Dihadron production with transversely polarized target H. Avakian, POETIC, Sep arXiv: Significant asymmetries observed at HERMES and COMPASS Large acceptance of CLAS12 makes dihadron production a perfect tool to extract transversity

H. Avakian, POETIC, Sep Dihadron A UT with CLAS days of transversely polarized HD will allow precision measurement of the transversity distribution. in models extract h 1 u Use Belle measurement

 production in the target fragmentation region Projected results of the longitudinal spin transfer as a function of x F (red full circles) compared with the CLAS preliminary data and the ISM prediction polarization tranfer coefficient 60 days of CLAS12 data taking 32 H. Avakian, POETIC, Sep 23

33 Dihadron production with CLAS12 Use the clasDIS (LUND based) generator + FASTMC to study   pairs x F - momentum in the CM frame Dihadron sample defined by SIDIS cuts+x F >0 (CFR) for both hadrons   CFR-CFR

H. Avakian, POETIC, Sep Dihadron production with CLAS12 Use the clasDIS (LUND based) generator + FASTMC to study   and   pairs x F - momentum in the CM frame Dihadron sample defined by SIDIS cuts+x F >0 (CFR) for both hadrons    CFR-CFR   TFR

Transversity extraction from single-hadron SSAs No simple way to extract transversity A model independent TMD flavor decomposition procedure is required to estimate the systematic error of extraction of transversity TMD. Bessel weighting procedure proposed by Boer, Gamberg, Musch &Prokudin arXiv: requires detailed measurements in a wide kinematic range in x,z and P T ! Fourier transforms to b T -space 35 H. Avakian, POETIC, Sep 23

36 BELLE projections for K+  - K  pairs in SIDIS h1h1 h2h2 K  pairs will provide complementary information on transversity and hadronization of pairs. Hadronization in Current Fragmentation Region CFR-CFR H. Avakian, POETIC, Sep 23

37 Models vs Lattice Models agree on a large e/f 1 -> large beam SSA for  pair production Lattice results for u-d can be directly compared to models and data. H. Avakian, POETIC, Sep 23 Musch et al, arXiv:

H. Avakian, POETIC, Sep Di-hadron production and transversity distribution Di-hadron production provides, a complementary to Collins effect, measurement of the leading twist transversity distribution, h 1 LCCQM spectator model Soffer bound M. Anselmino et al., (2009) A. Bacchetta et al.(2008) B. Pasquini et al(2007)