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