Slide 1

Contalbrigo Marco INFN FerraraJLab PAC 39 Open sessionJune 18, 2012 Newport NewsTransverse spin effects in SIDIS at 11 GeV with transversely polarized targetusing the CLAS12 detector(A CLAS12 experiment proposal for PAC39)A CLAS12 proposal for PAC38

A CLAS12 Proposal For PAC38Physics Motivations

PDFs fpu(x),TMD PDFs: fpu(x,kT),d2kTx=0,t=0Wpq(x,kT,r) Mother Wigner distributions d3r d2kTExclusive MeasurementsMomentum transfer to targetDirect info about spatial distributionSemi-inclusive measurementsMomentum transfer to quarkDirect info about momentum distribution(FT)GPDs: Hpu(x,x,t), Quantum phase-space distributions of quarks

pT< 2 GeV/cs = 20 GeV xFANMay solveproton spin puzzle

May explain SSAProbability to find a quark q in a nucleon P with a certain polarization in a position r & momentum k 4 JLab PAC 39, 18th June 2012, Newport NewsContalbrigo M.PR 12-105Exclusive Physics: DVCS with Transverse TargetPR 12-105SIDIS Physics: di-hadron with Transverse Target4ULTULTQuark polarisationNucleon polarisation

Number Density

Helicity

Transversity

Sivers

Boer MuldersCLAS12 has access to all of them through specific azimuthal modulations (f, fS) of the cross-section thanks to the polarized beam and targetPretzelosity

Worm-gear

Worm-gearC12-11-111This proposalBoer-Mulders for pions and kaonsLeading Twist TMDs5Contalbrigo M.E12-06-112E12-09-008Spin-effects forpions and kaonsE12-07-107E12-09-009

Quark number and helicitiesE12-09-007 JLab PAC 39, 18th June 2012, Newport News5E12-09-007 polarized and unpolarized (qui e collineare ?)

N/qULTULTLeading Twist TMDsquark polarisationnucleon polarisationInterference between wave functions with different angular momenta: contains information about parton orbital angular motion and spin-orbit effectsOther elements:

Number

Helicity

Sivers

Boer-Mulders

DensitySurvives transverse momentum integration (missing leading-twist collinear piece)

Differs from helicity due to relativistic effects and no mix with gluons in the spin-1/2 nucleon

Wants multidimensional approach to investigatefactorization and transverse momentum dependenceTransversity:Worm-gearWorm-gear

6Contalbrigo M.

Transversity

DFFF JLab PAC 39, 18th June 2012, Newport News6Mettere pretzelosity e SIDIS xsec

The Collins amplitude7Contalbrigo M.

Consistent non-zero signals for pions

Opposite sign for pions reveal Collins features

Puzzle in (low-statistics) kaon signals: K+ amplitudes larger then p+ K- amplitudes are not in agreementHERMESCOMPASS

Access to transversity and Collins functions JLab PAC 39, 18th June 2012, Newport News7

Transversity Signals8Contalbrigo M.

1st collinear extraction !

1st extraction of Transversity!Anselmino et al. Phys. Rev. D 75 (2007) Soffer boundxh1(x)dxh1(x)uxh1(x, k )T uxh1(x, k )T dBacchetta et al., PRL 107 (2011) NO DATAGauss Ansatz JLab PAC 39, 18th June 2012, Newport NewsFirst extractions Role of Q2 evolution

High-x and tensor charge?8The Sivers effect9Contalbrigo M.

HERMESNon zero signals for p+ and K+

Significant Q2 evolution ?

K+ signals larger than p+

Related to quark orbital angular momentum?

arXiv: 1107.4446

arXiv:1112.4423 JLab PAC 39, 18th June 2012, Newport News9The Sivers effect10Contalbrigo M.

Sign mismatch between SIDIS and pp SSA ??Coverage at large pT and relation with twist-3 collinear approach

arXiv: 1103.1591T3 correlator from ppSivers moment from SIDIS

Sivers effect from SIDIS to Drell-YanSign change is a crucial test of TMDs factorization?Coverage at large x and relation with Drell-YanarXiv: 0901.3078 JLab PAC 39, 18th June 2012, Newport News10

The Pretzelosity11Contalbrigo M.

HERMES pCOMPASS p Statistical power of existing data is not enough to observe significant signals

pretzelosity still basically unknown!Sensitive to the D-wave component andthe non spherical shape of the nucleon?

Few % signalexpected at Jlabfrom relativistic covariant model0.51 GeV2 and W2 > 4 GeV2

Cover valence region at several GeV Q2Constrain sub-leading twist terms 0.3 < z < 0.7

Current fragmentationNo exclusivity corner PT > 1 GeV/c

Limit given bycross-section JLab PAC 39, 18th June 2012, Newport News23

CLAS12 Kinematic Coverage24Contalbrigo M.Intermediate anguar range (15-25o) mandatory to reach high PT valuesLarge electron scattering angles (> 20o) mandatory to reach high Q2 valuesElectronThe CLAS12 forward detector is perfectly suitable for high-Q2 and high-pT measurements since designed to cover up to 40 degrees anglesElectronp+

acceptance JLab PAC 39, 18th June 2012, Newport News24ProjectionsSystematic uncertaintyEstimates based on:

Current knowledge on HD-Ice target

- Experience from CLAS/HERMES measurements

Reduces with statistics and bin number

Benefits from the large acceptance Dominated by uncertainties in transfer losses between cryostats

Optimization after tests in fall26Contalbrigo M.13 36 14 13 4 2~ 58 JLab PAC 39, 18th June 2012, Newport News26FARE SLIDE CON SYS BANDDIRE CHE E conservative estimateBACKUP PLOT CON PHI-PhiS coverage

ATT: la sys sulla polarizzazione e 5% nel proposalRange for sys .. What we loose se riducono bin by a factor 2, che succede per high pT region ?Single- and Double-Spin asymmetries27Contalbrigo M.

Analysis: the relevant Fourier amplitudes (Collins, Sivers, etc) are extracted simultaneously, thanks to their specific azimuthal dependence, by fitting (ML unbinned in f,fS) the yield (cross-section) asymmetries for opposite spin statesequivalent to the cross-section asymmetry for opposite spin statesExperiment: CLAS12 with HD-Ice transversely polarized target 75 % polarization and 1/3 dilution for Hydrogen @ 1034 cm-2 s-1 RICH detector for flavor tagging pions, kaons and protons ID in the 3-8 GeV/c momentum range JLab PAC 39, 18th June 2012, Newport News27Beckup slide with phi coverageMostrare come viene fatta analisi

AGGIUNGERE TAGLI

CLAS12 Projections28Contalbrigo M.Collins asymmetry Large x important to constrain the tensor chargeSivers asymmetry Large pT important to test perturbative to non-perturb. transient and for Bessel function analysis

JLab PAC 39, 18th June 2012, Newport News28Bacup quelle per pretzelosity e wrom gear

Statistical precision29Contalbrigo M.

4D analysis is possible

The wanted high-Q2 high-pT defines the beam-time request Stat. error for a 4D analysis of the p+ Sivers asymmetryon proton (x1.5 on D) target 2D projection (x-pT) of the p+ Sivers asymmetry

JLab PAC 39, 18th June 2012, Newport News29Fare plot bigger o blow up qhile discussingThe main goals30Contalbrigo M.Main interest on transverse-target single and double spin asymmetries;

Access to leading-twist poorly known or unmeasured TMD PDFs which provide 3-dimensional picture of the nucleon in momentum space (nucleon tomography);

* SSA Transversity, Sivers, Pretzelosity functions;

* DSA Worm-gear function;

Multi dimensional analysis in x, Q2, z, pT thanks to large-acceptance and high-luminosity;

* disentangle parton distribution from fragmentation functions (x vs z);

* isolate sub-leading-twist effects from 1/Q dependence;

* investigate transverse degrees of freedom and perturbative to non-perturbative QCD transient from pT dependence;

Together with already approved experiments with unpolarized and longitudinally polarized targets, complete the mapping of the TMD table at CLAS12.Transverse spin effects in SIDIS at 11 GeV with transversely polarized target using the CLAS12 detector JLab PAC 39, 18th June 2012, Newport News30

DC R3R2R1EC TorusFTOFPCALHTCCSolenoid RICHHD-IceBeam time request31Contalbrigo M.The proposed experiment requires:

11 GeV (highly polarized) electron beam

CLAS12 detector equipped with:

- HD-Ice transversely polarized target

- Suitable magnetic system (compensation + saddle coil)

- RICH (pion/kaon separation within 3-8 GeV/c)In order to reach the desired statistical precision at high-x (valence region) and high pT for both pion and kaons, and toallow a fully differentyal analysis in x,Q2,z,pT

we ask the PAC to award 110 days of beam time

(including 10 days for calibrations, empty target runs, supportive tests, etc.) JLab PAC 39, 18th June 2012, Newport News31HDice operations during g14 / E06-101 HD targets condensed, polarized and aged to the Frozen-Spin state in HDice Lab (TestLab annex)

transferred as solid, polarized HD between cryostats; moved to Hall B

In-Beam Cryostat (IBC) operates in Hall at 50 mK, 0.9 tesla

g14 ran from Nov/11 to May/12 with 15mm 50mm long HD cells

-beam lifetimes ~ years with 108 /s

HD targets used for eHD tests in Feb/12 and Mar/12

H polarization does not appear to suffer radiation damage with 1 nA; D does

heat removal needs improvement faster raster, larger diameter cell, additional cooling wires,

HD polarization during g14/E06-101