h. avakian, poetic, sep 23 1 harut avakian (jlab) di-hadron measurements at jlab measurements of...

H. Avakian, POETIC , Sep 231

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 232

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 233

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 234

h1

h2

Dihadron productions offers exciting possibility to access transversity distribution as we deal with the product of functions instead of convolution

BNL

arXiv:1106.5897

• Factorization proven• Evolution known• Extracted at BELLE for pp pairs, planned for pK pairs

RT≅transverse to g* component of the transverse to pair total momentum, P, component of R

Dihadron cross sections with transverse target

H. Avakian, POETIC , Sep 235

Similar to single hadron SIDIS with fRfh

H. Avakian, POETIC , Sep 236

Accessing transversity from target SSA

• Target spin asymmetry can be presented as a flavor sum of products of PDF and FF.• SSA AUT 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 PbWO4

~87% ~8% ~1.5%

H. Avakian, POETIC , Sep 23

H. Avakian, POETIC , Sep 238

Scattering of 5.7 GeV electrons off polarized proton and deuteron targets

SIDIS with JLab at 6 GeV

DIS kinematics, Q2>1 GeV2, W2>4 GeV2, y<0.85 0.4>z>0.7, MX

2>2 GeV2

2

epX

Large acceptance and full coverage in azimuthal angle f allows di-hadron measurements in DIS kinematics

Dihadron simulations with LUND-MC @6 GeV

H. Avakian, POETIC , Sep 239

Reasonable agreement with LUND-MC already at 6 GeV

H. Avakian, POETIC , Sep 2310

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/f1 -> 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:1011.1213

CLAS/HERMES

Force on the active quark right after scattering (Burkardt)

H. Avakian, POETIC , Sep 2312

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 2313

Dihadron production at JLAB12 Use the clasDIS (LUND based) generator + FASTMC

to study pp pairs xF - momentum

in the CM frame

Dihadron sample defined by SIDIS cuts+xF>0 (CFR) for both hadrons

pp

Wide angular coverage is important

SoLIDCLAS12

H. Avakian, POETIC , Sep 2314

Dihadron production with CLAS12

CLAS12 will provide precision measurements of target spin asymmetries in a wide range of x and Q2 in dihadron pair production in SIDIS

p p

.1

Missing mass of ppsystem

Invariant mass of K p system

H. Avakian, POETIC , Sep 2315

Accessing transversity in dihadron production at JLab Measurements with polarized protons Measurements with polarized neutrons

CLAS12 SoLID

H. Avakian, POETIC , Sep 2316

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 2317

Accessing Sivers TMD in dihadron production at JLab

• Measurements with polarized protons @ CLAS12

• Measurements with polarized neutrons @SOLID• Measurements with EIC

A. Kotzinian, H. H. Matevosyan, and A. W. Thomas,Phys.Rev.Lett. 113, 062003 (2014), 1403.5562.

After integration over the azimuthal angle of total transverse momentumThe asymmetry as a function of the relative transverse momentum

1st harmonic of the cos(fT-fR)

sR≠0 can be ensured, by choosing asymmetric cuts on the minimum values of z1 and z2.

SOLID-predicted

Target fragmentation region: L production

polarization tranfer coefficient

60 days of CLAS12

18H. 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 2319

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 cSB

(Schweitzer et al)• ...

P2

P1

H. Avakian, POETIC , Sep 2320

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 Q2, 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 , )p pp pairs in SIDIS provide qualitatively new possibilities to:

Significant SSA observed in hadron pair production in SIDIS

H. Avakian, POETIC , Sep 2321

Support slides….

Definitions of fR in dihadron production

H. Avakian, POETIC , Sep 2322

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 2323

Dihadron ALU 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 2324

SSAs for p+ and K+ are large, while those for p- and K- relatively small.

H. Matevosyan

SSAs for p+ drops with energy

1-hadron

2-hadron

H. Avakian, POETIC , Sep 232525

Transverse force on the polarized quarks

Quark polarized in the x-direction with kT 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:0810.3589)

pion-nucleon s-term

ALU in b2b SIDIS with CLAS @ 5.5 GeV

H. Avakian (JLab) , TM-2014, Sep 13-15

26

Preliminary results for a significant ALU asymmetry from CLAS with π+ produced in CFR and π− – in TFR.

L production in the target fragmentation region

(LEPTO 4x60)

direct L

hyperon decay L

e’p

e

Λ -p

H. Avakian (JLab) , TM-2014, Sep 13-15

angular distributions of protons and ani-protons

Most of the direct Lambdas in the target fragmenatation region

anti-LX

(x10)LX

27

correlations between target and current

H. Avakian (JLab) , TM-2014, Sep 13-15

28

H. Avakian, POETIC , Sep 23

Dihadron Fragmentation

• Evolution effects small for DiFF/D1

• 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 2330

arXiv:1106.5897

Significant asymmetries observed at HERMES and COMPASSLarge acceptance of CLAS12 makes dihadron production a perfect tool to extract transversity

H. Avakian, POETIC , Sep 2331

Dihadron AUT with CLAS12

100 days of transversely polarized HD will allow precision measurement of the transversity distribution.

in models extract h1u

Use Belle measurement

L production in the target fragmentation region

Projected results of the longitudinal spin transfer as a function of xF (red full circles) compared with the CLAS preliminary data and the ISM prediction

polarization tranfer coefficient

60 days of CLAS12 data taking

32H. Avakian, POETIC , Sep 23

H. Avakian, POETIC , Sep 2333

Dihadron production with CLAS12 Use the clasDIS (LUND based) generator + FASTMC to study pp pairs

xF - momentum in

the CM frame

Dihadron sample defined by SIDIS cuts+xF>0 (CFR) for both hadrons

pp

CFR-CFR

H. Avakian, POETIC , Sep 2334

Dihadron production with CLAS12 Use the clasDIS (LUND based) generator + FASTMC to study pp and pK pairs

xF - momentum

in the CM frame

Dihadron sample defined by SIDIS cuts+xF>0 (CFR) for both hadrons

pp

pK

CFR-CFR

pp

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:1107.5294 requires detailed measurements in a wide kinematic range in x,z and PT!

Fourier transforms to bT-space

35H. Avakian, POETIC , Sep 23

36

BELLE projections for K+p-

K p pairs in SIDIS

h1

h2

K p 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/f1 -> large beam SSA for pp pair production• Lattice results for u-d can be directly compared to models and data.

H. Avakian, POETIC , Sep 23

Musch et al, arXiv:1011.1213

H. Avakian, POETIC , Sep 2338

Di-hadron production and transversity distribution

Di-hadron production provides, a complementary to Collins effect, measurement of the leading twist transversity distribution, h1

LCCQM

spectator model

Soffer bound

M. Anselmino et al., (2009)

A. Bacchetta et al.(2008)

B. Pasquini et al(2007)