Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the...

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

Transcript of Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the...

Page 1: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

Studies of TMDs with CLAS & CLAS12

P. Rossi Laboratori Nazionali di Frascati - INFNOn behalf of the CLAS Collaboration

IntroductionSIDIS experiments @ JLab

with CLASResults @ 6 GeVCLAS12 and TMDs studies @ 12

GeVConclusions

May 18-21, 2010TJNAF-Newport News, Virginia USA

Page 2: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

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

Page 3: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

SIDIS experiments and SSAs

Inclusive DIS experiments- 2D image (collinear approx.)- unable to account for all the nucleon spin

k’, E’k, E

DF

1

2=

1

2ΔΣ + ΔG + Lq

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

Page 4: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

Jefferson Lab and CLAS

Beam: continuousEnergy: 0.8 - 5.7 GeVCurrent: 0.1nA - 200 APolarization: 75-85%

A B C

20 cryomodules

e p e’ h X1.high intensity beam with high polarization2.polarized targets3.high acceptance for the hadron

CLAS at JLab perfectly matches all this requirements

Lumi ~1034cm-2sec-1

CLASCLAS

e-

Data in 2011?

Data taken in 2001/2005/2009

Page 5: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

Experimental configuration for unpolarized/long.polarized target

Inner Calorimeter (424 PbWO4 crystals) to detect high energy photons at forward lab angles.

IC

Polarized target (NH3/ND3)Pol. NH3, ND3 targets <PH> =0.75, <PD>=0.3

Longitudinal polarization

Experimental configuration

Page 6: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

ep e’X DIS kinematics: Q2>1 GeV2, W2>4 GeV2, y<0.85

1) Longitudinally Polarized NH3/ND3 (no IC, ~5 days) 20012) Longitudinally Polarized NH3/ND3 with IC 60 days

20093) Unpolarized H

with IC ~60 days 20054) Transversely Polarized HD-

Ice (no IC, 25 days)

2011 (?)

AUL, ALL: arXiv:1003.4549Submitted to PRLNew data under analysisExperiment E05-113 0 BSA Analysis completedAnalysis note under coll. reviewExperiment in preparation

Q2

SIDIS with CLAS @ 6 GeV

Page 7: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

CLAS program: extraction of leading twist and higher twist TMDs

quark-gluon-quark correlations responsible for azimuthal moments of h.t.

ALUsin(φ ) 0 BSA

UU

U U

AULsin(2φ )0/+/- TSA

LL

L L

ALLPT-dependence

Pion SSA with unpol./long. Polarized target

Page 8: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

Transversely polarized quarks in a longitudinally polarized nucleon

H. Avakian et al. arXiv:1003.4549

~5 days data taking

• AUL over the full kinematics

• Fitting function: p1sin+p2sin2

+

p1= 0.047±0.010

p2=-0.042±0.010

p1= 0.046±0.016

p2=-0.060±0.016p1= 0.059±0.018

p2=-0.010±0.019

• No indication of Collins effect for 0

• Non-zero negative asymmetry for +/-

e p e’ X

~10% of E05-113 data

Longitudinal pol. Target Kotzinian-Mulders asymmetry

Page 9: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

H. Avakian et al. arXiv:1003.4549

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 AUL(sin2), ALL, ALU(sin) +/- AUL(sin2)

Projected results for Exp. E05-113

Longitudinal pol. Target Kotzinian-Mulders asymmetry

Page 10: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

Anselmino et. alPRD74,074015(2006)

Different width of TMDs of quarks with different flavor and polarizations

R =k⊥width dist(g1)

k⊥width dist( f1)

R=0.40

R=0.68

R=1.0

f1=0.25 GeV2

• Data shows slight preference for R<

H. Avakian et al. arXiv:1003.4549

+ 0 -

• New experiment with 10 times more data will study the PT-dependence for different quark helicities and flavors for bins in x

Projected results for Exp. E05-113

Longitudinal pol. Target: A1-PT dependence

Page 11: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

( ) −+

−+

+−

=NN

NN

PALU

ALUsin(φ )e p e’ X

BSA ~ sin insensitive to other harmonics

BSA: Asymmetry extraction and fitting for 0

Page 12: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

M Aghasyan, LNF-INFN

• Drop with PT below 1 GeV/c

• ALU in agreement with HERMES data

M Aghasyan, LNF-INFN

• Comparable BSA for 0 and +

Small Collins type contributions for +?M Aghasyan, LNF-INFN

⎪⎪⎩

⎪⎪⎨

⊗+⊗

⊗−⊗∝

⊥⊥

⊥⊥

z

EhHxe

z

Gf

M

MDxg

M

M

F

h

hLU

1

1

1

1

Main contribution?

0 BSA Asymmetry results

Page 13: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

Target used by LEGS at BNL with photon beamPros

• Small field (∫Bdl~0.005-0.05Tm)• 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 Hall January 2011• photon run with HD-ice March 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

Page 14: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

⊥⊥ ⊗∝11

)3( HhF TUT

11)1( DfF TUT ⊗∝ ⊥

Sivers

⊥⊗∝11

)2( HhFUT Collins

Sivers TMD

transversity TMD

Collins FF

pretzelosity TMD

Collins FF

( )STUT DfF φφ −⊗∝ ⊥ sin11)1(

Projected results for 30 days of CLAS at 6 GeV in 2011 (PT=75% L=5.1033cm-2s-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

Page 15: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

Hall A

•Beam: 6 GeV, 15 A (target limit)•Neutron Target: High pressure polarized 3He, 50 mg/cm2, Pol. ~

60%•Hadron Detection: HRS Left Ph = 2.4 GeV/c, /K ID•Kinematic Region<Q2> = 2.2 GeV2, x = 0.130.4, z ~ 0.5

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

Page 16: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

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

Page 17: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

CHL-CHL-22

Beam Current: 90 µAMax Pass energy: 2.2 GeVMax Enery Hall A,B,C: 11 GeV

May 2012

6 GeV Accelerator Shutdown starts

May 2013 Accelerator Commissioning starts

2013-2015

Pre-Ops (beam commissioning)

Solenoid 5T

DC R1, R2, R3 LTCC

HTCC

FTOF

PCAL

EC

CLAS12

L = 1035 cm-2s-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

CEBAF @ 12 GeV and CLAS12

Page 18: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

1 GeV2

Study of high xB 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

Page 19: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

E12-06-112:E12-06-112: Pion SIDIS E12-09-008: E12-09-008: Kaon SIDISE12-07-107:E12-07-107: Pion

SIDIS E12-09-009: E12-09-009: Kaon SIDISLOI12-06-108: LOI12-06-108: Pion SIDISLOI12-09-004: LOI12-09-004: Kaon SIDIS

PAC approved experiments & LoI

Nq

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 LTCCProject under development

TMDs program @ 12 GeV in Hall B

Page 20: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

Kaon TMDs program @ 12 GeV in Hall B

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 measurement @ CLAS12 will provide a more detailed knowledge of Sivers effect

epe’K+X

S.Arnold et al.0805.2137

M. Anselmino et al.0805.2677

Page 21: Studies of TMDs with CLAS & CLAS12 P. Rossi Laboratori Nazionali di Frascati - INFN On behalf of the CLAS Collaboration  Introduction  SIDIS experiments.

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 polarizationis essential for high precision measurements of 3D PDFs in the valence region

Conclusions and Outlook