Dave Mack (TJNAF) Workshop on Hadronic Physics in China and Opportunities with 12 GeV Jlab
Physics Program with 12 GeV JLab
description
Transcript of Physics Program with 12 GeV JLab
Physics Program with 12 GeV JLab
J. P. Chen, Jefferson LabEIC Workshop, APS-DNP/JPS Joint Meeting, 10/13/2009
Introduction and Overview
Nucleon Structure - Spin-Flavor Structure in Valance Region
Nucleon Structure - Generalized Parton Distributions
Nucleon Structure - Transverse Momentum Dependent Distributions
Nucleon Structure - Form Factors
Parity Violation Electron Scattering - Low Energy Test of Standard Model
Nuclear Physics: Hadronization, Short-Range Correlations, Few-Body
Exotic Meson Search: Gluon Excitations
•Acknowledgement: Some slides “borrowed” from colleague’s talks
QCD and Nucleon Structure• A major challenge in fundamental physics: Understand QCD in all regions, including strong (confinement) region
• Nucleon = u u d + sea + gluons• Structure mostly determined by strong interaction• Mass, charge, magnetic moment, spin, axial charge, tensor charge • Decomposition of each of the above fundamental quantities
Mass: ~1 GeV, but u/d quark mass only a few MeV each! Momentum: total quarks only carry ~ 50% Spin: ½, total quarks contribution only ~30% Spin Sum Rule
Tensor charge Transverse sum rule?• Multi-dimensional structure and distributions• Confinement -- QCD vacuum: gluon field and sea
Jefferson Lab Experimental Halls
HallA: two HRS’ Hall B:CLAS Hall C: HMS+SOS
6 GeV polarized CW electron beam Pol=85%, I=180A
Luminosity ~ 1039
Polarized ~ 1036
Will be upgraded to 12 GeV by ~ 2014
Hall A polarized 3He target
longitudinal, transverse and verticalLuminosity = 1036
P(in-beam) = 65%Effective polarized neutron
P=65%
@ I=15 uA
Hall B/C Polarized p/d target
• Polarized NH3/ND3 targets
• Luminosity ~ 1035 (Hall C), ~ 1034 (Hall B)• In-beam average polarization
70-90% for p, 30-40% for d
CHL-2CHL-2
Upgrade magnets Upgrade magnets and power suppliesand power supplies
Enhance equipment in Enhance equipment in existing hallsexisting halls
6 GeV CEBAF1112Add new hallAdd new hall
Experimental Halls
• (new) Hall D: linear polarized photon beam, Selonoid detetcor GluoX collaboration: exotic meson spectroscopy gluon-quark hybrid, confinement
• Hall B: CLAS12 GPDs, TMDs, …
• Hall C: Super HMS + existing HMS Form factors, structure functions, …
• Hall A: Dedicated devices + existing spectrometers Super BigBite, Solenoid, Moller Spectrometer SIDIS, PVDIS, …
Overview of Physics Program
• Gluonic Excitations and the Origin of Confinement • Nucleon Structure
• Quark spin-flavor structure in valence region• Deep Exclusive Reactions (DVCS, DVMP) to study GPDs • SIDIS to measure Transversity and TMDs• Form Factors – Constraints on the GPDs
• Symmetry Tests
• Parity violation to test Standard Model and precision study of hadronic physics • The Physics of Nuclei
• Medium Effects: Hadronization, EMC effects• Short-Range Correlations• Few-Body
12 GeV Upgrade Kinematical Reach
• Reach a broad DIS region • Decisive inclusive DIS
measurements at high-x • Precision Deep Exclusive
Reactions (e.x. DVCS) to study GPDs
• Precision SIDIS for transversity and TMDs
• Parity Violating DIS to test Standard Model and precision study of hadronic physics
StructureFunctionsatHighx
ValenceQuarkDistributions
Hall A 11 GeV with HRSBONUS at Hall B 11 GeV with CLAS12
F2n/F2
p d/u ratio at high-x
HallBCLAS,Phys.Lett.B641(2006)11 HallAE99-117,PRL92,012004(2004)PRC70,065207(2004)
JLab 6 GeV Results on A1 at high x
SU(6)
pQCD
Inclusive Hall A and B and Semi-Inclusive Hermes
BBS
BBS+OAM
F. Yuan, H. Avakian, S. Brodsky, and A. Deur, arXiv:0705.1553
Polarized Parton Distribution at Large xpQCD with Quark Orbital Angular Momentum
A1p at 11 GeV
Projections for JLab at 11 GeV
pQCD
SU(6)
u and d at JLab 11 GeV
Polarized Sea
JLab @11 GeV
Flavor Decomposition with SIDIS
GeneralizedPartonDistributions
3-dQuark-GluonStructureoftheNucleon
Beyond form factors and quark distributions – Generalized Parton Distributions (GPDs)
Proton form factors, transverse charge & current densities
X. Ji, D. Mueller, A. Radyushkin, …
M. Burkardt, … Interpretation in impact parameter space
Structure functions,quark longitudinalmomentum & helicity distributions
Correlated quark momentum and helicity distributions in transverse space - GPDs
GPDs & Deeply Virtual Exclusive Processes
x
Deeply Virtual Compton Scattering (DVCS)
t
x+ x-
H(x,,t), E(x,,t), . .
hardvertices
– longitudinal momentum transfer
x – longitudinal quark momentum fraction
–t – Fourier conjugateto transverse impact parameter
“handbag” mechanism
xB
2-xB
=
Twist 2 contribution
Twist 3 contribution strongly suppressed
Hall A E00-110 Demonstrated HandbagDominance at Modest Q2
The Twist-2 term can be extracted accurately from the cross-section differenceDominance of twist-2 handbag dominance DVCS interpretation straightforward
Deeply Virtual Exclusive Processes - Kinematics Coverage of the 12 GeV Upgrade
JLab Upgrade
UpgradedJLabhascomplementary&uniquecapabilities
uniquetoJLaboverlapwithotherexperiments
HighxBonlyreachablewithhighluminosityH1,ZEUS
DVCS/BH- Beam Asymmetry
With large acceptance,measure large Q2, xB, t ranges simultaneously.
A(Q2,xB,t) (Q2,xB,t)
(Q2,xB,t)
Ee = 11 GeV
ALU
CLAS12– L/T Separationepep
L
T
xB=0.3-0.4-t=0.2-0.3GeV2
Other bins measured concurrently
Projections for 11 GeV(sample kinematics)
SingleSpinAsymmetryinSemi-inclusiveDIS
TransverseMomentumDependentDistributions
“Leading-Twist” TMD Quark Distributions
Quark
Nucleon
Unpol.
Long.
Trans.
Unpol. Long. Trans.
JLab 6 GeV experiment (E06-010/06-011)
SSA in SIDIS n↑(e,e′π+/-) on a Transversely Polarized 3He Target
Collins
Sivers
First neutron (3He) measurement
Completed data taking in 2/2009
Spokespersons:X. Jiang (Los Alamos)J.P. Chen (JLab)E. Cisbani (INFN)H. Gao (Duke)J.-C. Peng (UIUC)
PhD Students:K. Allada (UKy)C. Dutta (UKy)J. Huang (MIT)J. Katich (W&M)X. Qian (Duke)Y. Wang (UIUC)Y. Zhang (Lanzhou)
3He target
12 GeV: Solenoid detector for SIDIS and PVDIS
GEMs
Gas Cerenkov
Calorimeter
GEMs
Projection vs PT and x for + (60 days)
• For one z bin
(0.5-0.6)
• Will obtain 4
z bins (0.3-0.7)
• Also - at same
time
• With upgraded
PID for K+ and K-
3-D Projections for Collins and Sivers Asymmetry (+)
ParityViolatingElectronScattering
TestStandardModelandPrecisionStudyofHadronStructure
Parity Violating DIS
C1u and C1d will be determined to high precision by Qweak, APV Cs
C2u and C2d are small and poorly known: one combination can be accessed in PV DIS
New physics such as compositeness, leptoquarks:
Deviations to C2u and C2d might be fractionally large
A
V
V
A
Moller PV is insensitive to the Cij
PVDIS with SoLID
• High Luminosity on LH2 & LD2
• Better than 1% errors for small bins
• x-range 0.25-0.75
• Moderate running times
Physics Implications
Examples:•1 TeV extra gauge bosons (model dependent)•TeV scale leptoquarks with specific chiral couplings
Unique, unmatched constraints on axial-vector quark couplings:Complementary to LHC direct searches
(2C2u-C2d)=0.012
(sin2W)=0.0009
PV DIS and Nucleon Structure
• PVDIS provide precision study of hadron structure:
– Higher twist effects– Charge Symmetry Violation (CSV)– d/u at high x
• JLab at 11 GeV offers new opportunities
– PV DIS can address issues directly• Luminosity and kinematic coverage• Outstanding opportunities for new discoveries• Provide confidence in electroweak measurement
Parity Violating Moller Scattering
QWe
modified
sin2W runs with Q2
• Semileptonic processes have theoretical uncertainties • E158 established running, probing vector boson loops• JLab measurement would have impact on discrepancy between leptonic and hadronic Z-pole measurements
(sin2W) ~ 0.0003Comparable to single collider measurements
HadronizationinNuclearSIDIS
QuarkPropagationThroughNuclei
NuclearDeepInelasticScatteringandHadronization
Wecanlearnabouthadronizationdistancescalesandreactionmechanismsfromsemi-inclusivenuclearDIS
Nucleusactsasaspatialfilterforoutgoinghadronizationproducts
Initialfocusonpropertiesofleadinghadron;correlationswithsubleadinghadronsandsoftprotonsalsoofinterest.
(GeV) z
Observables–HadronicMultiplicityRatio(≈medium-modifiedfragmentationfunction)
In general, h = , K, , p, .…
Significant dependence of R on Apz T ,,, 2
MustMust measure multi-variable dependence for stringent model tests!
<z>=0.3-0.42, <Q2>=2.2-3.5 <>=11.5-13.4, <Q2>=2.6-3.1
Each point is differential in Q2, , z, and A; all are acquired simultaneously
12
GeV
Anti
cipate
d D
ata
12
GeV
Anti
cipate
d D
ata
Summary• 12 GeV JLab with high luminosity (1039 unpol., 1036-1037 pol.) and
large acceptance will lead us to a new precision frontier • Provide precision data on multi-dimension nucleon structure and
a deep understanding of strong interaction:• Spin-flavor structure in the valence region • Generalized Parton Distributions with DVCS and limited DVMP • Transverse Spin and TMDs with SIDIS
• Parity violating electron scattering provide precision low-energy tests of standard model and a precision tool to study hadronic physics
• Precision Study of hadronization and nuclei medium effects• Other important physics opportunities:
• GlueX, Form Factors, Short-range Correlations, Few-Body, J/…
Strong Interaction and QCD
• A major challenge in fundamental physics: Understand QCD in all regions, including strong interaction (confinement) region
• Strong interaction, running coupling ~1 -- QCD: accepted theory for strong interaction -- asymptotic freedom (2004 Nobel) perturbation calculation works at high energy -- interaction significant at intermediate energy quark-gluon correlations -- interaction strong at low energy (nucleon size) confinement, chiral symmetry breaking
E
s
New Hall D, Enhanced Existing Halls A, B & C
9 GeV tagged polarized photons and a 4 hermetic detector
D
Super High Momentum Spectrometer (SHMS) at high luminosity and forward angles
C
CLAS upgraded to higher (1035 cm-2s-1) luminosity and coverage
B
Retain HRS Pair for continuation of research in which resolution comparable to nuclear level spacing is essential. Use Hall to stage “one-of-a-kind” specialized experiments requiring unique apparatus.
A
Why Are PDFs at High x Important?
• Valence quark dominance: simpler picture
-- direct comparison with nucleon structure models
SU(6) symmetry, broken SU(6), diquark• x 1 region amenable to pQCD analysis
-- hadron helicity conservation?• Clean connection with QCD, via lattice moments• Input for search for physics beyond the Standard Model at high
energy collider
-- evolution: high x at low Q2 low x at high Q2
-- small uncertainties amplified
-- example: HERA ‘anomaly’ (1998) • Input to nuclear, high energy physics calculations
Proton Neutron
World Data on A1
Color “Polarizabilities”Color “Polarizabilities”
E08-027 “g2p”SANE
“d2n” just completed in Hall A
6 GeV Experiments
Sane: just completed in Hall C
“g2p” in Hall A, 2011
projected
Jlab 6 GeV Results on d2
Color Polarizability d2n with JLab 12 GeV
• Projections with 12 GeV experiments Improved Lattice Calculation (QCDSF, hep-lat/0506017)
Link to DIS and Elastic Form Factors
),,(~,~,, txEHEH qqqq
JG = 1
1
)0,,()0,,(21
21 xExHxdxJ qqq
Quarkangularmomentum(Ji’ssumrule)
X.Ji,Phy.Rev.Lett.78,610(1997)
DISat =t=0
)(),()0,0,(~)(),()0,0,(
xqxqxH
xqxqxHq
q
Formfactors(sumrules)
)(),,(~,)(),,(~
)Diracf.f.(),,(
,
1
1,
1
1
1
tGtxEdxtGtxHdx
tF1txHdx
qPq
qAq
q
q
)Paulif.f.(),,(1
tF2txEdxq
q
Access GPDs through DVCS x-section & asymmetries
Accessedbycrosssections
Accessedbybeam/targetspinasymmetry
t=0
Quarkdistributionq(x)
-q(-x)
DIS measures at =0
DVCS interpreted in pQCD at Q2 > 1 GeV2
ALU E=5.75 GeV
<Q2> = 2.0GeV2
<x> = 0.3<-t> = 0.3GeV2
CLAS preliminary
[rad]
Pioneering DVCS experiments First GPD analysesofHERA/CLAS/HERMES datainLO/NLO consistentwith ~ 0.20.A.Freund(2003),A.Belitskyetal.(2003)
Full GPD analysis needs high statistics and broad coverage
twist-3twist-2
AUL=sin+sin2
twist-3 contributions are small
CLAS12- DVCS/BH Target Asymmetry
epep
<Q2> = 2.0GeV2
<x> = 0.2<-t> = 0.25GeV2
CLAS preliminary
E=5.75 GeVAUL
Longitudinally polarized target
~sinIm{F1H+(F1+F2)H...}d~
E = 11 GeVL = 2x1035 cm-2s-1
T = 1000 hrsQ2 = 1GeV2
x = 0.05
DVCSDVCS DVMPDVMP
GPDs – Flavor separation
hardvertices
hardgluon
Photons cannot separate u/d quarkcontributions.
long.only
M = select H, E, for u/d flavorsM = , K select H, E
transverse polarized target
3D Images of the Proton’s Quark Content
M. Burkardt PRD 66, 114005 (2002)
b - Impact parameterT
u(x,b )T d(x,b )T uX(x,b )T
dX(x,b )T
Hu EuNeeds: HdEd
quark flavor polarization
Accessed in Single Spin Asymmetries.
Transversity and TMDs
• Three twist-2 quark distributions (integrated over P┴) :
• Momentum distributions: q(x,Q2) = q↑(x) + q↓(x)• Longitudinal spin distributions: Δq(x,Q2) = q↑(x) - q↓(x)
• Transversity distributions: δq(x,Q2) = q┴(x) - q┬(x)
• Tensor charge: integral of transversity over x
• TMDs (without integrating over PT), 8 distributions + fragmentation functions:
• Distribution functions depends on x, k┴ and Q2 : δq, f1T┴ (x,k┴ ,Q2), …
• Fragmentation functions depends on z, p┴ and Q2 : D, H1(x,p┴ ,Q2)
• Measured asymmetries depends on x, z, P┴ and Q2 : Collins, Sivers, …
(k┴, p┴ and P┴ are related)
AUTsin() from transv. pol. H target
Simultaneous fit to sin( + s) and sin( - s)
`Collins‘ moments
• Non-zero Collins asymmetry
• Assume q(x) from model, then
H1_unfav ~ -H1_fav
• Need independent H1 (BELLE)
`Sivers‘ moments
•Sivers function nonzero (+) orbital angular momentum of quarks
•Regular flagmentation functions
PKU-RBRC Workshop on Transverse Spin Physics, June 30, 2008PKU-RBRC Workshop on Transverse Spin Physics, June 30, 2008 F. BradamanteF. Bradamante
Collins asymmetry – proton datacomparison with M. Anselmino et al. predictions Franco Bradamante
Transverse2008, Beijing
PKU-RBRC Workshop on Transverse Spin Physics, June 30, 2008PKU-RBRC Workshop on Transverse Spin Physics, June 30, 2008 F. BradamanteF. Bradamante
Sivers asymmetry – proton datacomparison with the most recent predictions from M. Anselmino et al. Franco Bradamante
Transverse2008, Beijing
Current Status• Large single spin asymmetry in pp->X• Collins Asymmetries
- sizable for proton (HERMES and COMPASS) large at high x, large for -
- and has opposite sign unfavored Collins fragmentation as large as favored (opposite sign)? - consistent with 0 for deuteron (COMPASS)
• Sivers Asymmetries - non-zero for + from proton (HERMES), consistent with zero (COMPASS)? - consistent with zero for - from proton and for all channels from deuteron - large for K+ ?
• Very active theoretical and experimental study RHIC-spin, JLab (Hall A 6 GeV, CLAS12, HallA/C 12 GeV), Belle, FAIR (PAX)
• Global Fits/models by Anselmino et al., Yuan et al. and …
• Solenoid with polarized 3He at JLab 12 GeV Unprecedented precision with high luminosity and large acceptance
Precision Study of Transversity and TMDs
• From exploration to precision study• Transversity: fundamental PDFs, tensor charge• TMDs provide 3-d structure information of the nucleon• Laboratory to study QCD• Learn about quark orbital angular momentum• Multi-dimensional mapping of TMDs
• 3-d (x,z,P┴ ) • Q2 dependence • multi facilities, global effort
• Precision high statistics• high luminosity and large acceptance
Discussion• Unprecedented precision 3-d mapping of SSA
• Collins, Sivers and other TMDs• +, - and K+, K-
• Study factorization with x and z-dependences • Study PT dependence• Combining with CLAS12 proton and world data
• extract transversity and fragmentation functions for both u and d quarks• determine tensor charge• study TMDs for both valence and sea quarks • study quark orbital angular momentum
• Combining with world data, especially data from high energy facilities• study Q2 evolution
• Global efforts (experimentalists and theorists), global analysis• much better understanding of 3-d nucleon structure and QCD
•The couplings depend on electroweak physics as well as on the weak vector and axial-vector hadronic current •Both new physics at high energy scales as well as interesting features of hadronic structure come into play•A program with many targets and a broad kinematic range can untangle the physics
(gAegV
T + gV
egAT)
PV Electron Scattering on Hadron
PAC34
Statistical Errors (%) vs Kinematics
4 months at 11 GeV
2 months at 6.6 GeV
Error bar σA/A (%)shown at center of binsin Q2, x
For SOLID Spectrometer
12 GeV PVDIS Sensitivity: C1 and C2 Plots
Cs
PVDIS
Qweak PVDIS
World’s data
Precision Data
6 GeV
CSV Theory and Data
MRST PDF global with fit of CSVMartin, Roberts, Stirling, Thorne [Eur Phys J C35, 325 (04)]:
Analytic calculation similar to global fit
Londergan & Thomas, (also B. Ma)
Search for CSV in PV DIS
Sensitivity will be further enhanced if u+d falls off more rapidly than u-d as x 1
• u-d mass difference• electromagnetic effects
•Direct observation of parton-level CSV would be very exciting!
•Important implications for high energy collider pdfs
•Could explain significant portion of the NuTeV anomaly
up (x)dn (x)?
d p (x)un (x)?
For APV in electron-2H DIS: du
du
A
A
PV
PV
28.0
u(x)up (x) dn (x)
d(x)d p (x) un (x)
Sensitivity with PVDIS
RCSV APV x APV x 0.28
u x d x u x d x
Study Higher-Twist in PVDIS
• Twist-2 (mostly) cancel in asymmetry• Twist-4 is (basically) leading twist• Clean access twist-4 effect: free from twist-2 order
dependence• Study quark-quark correlations
Coherent Program of PVDIS Study
• Measure AD in NARROW bins of x, Q2 with 0.5% precision• Cover broad Q2 range for x in [0.3,0.6] to constrain HT• Search for CSV with x dependence of AD at high x• Use x>0.4, high Q2, and to measure a combination of the Ciq’s
Strategy: requires precise kinematics and broad range
x y Q2
New Physics no yes no
CSV yes no no
Higher Twist yes no yes
2
23)1(
11 x
QxAA CSVHT
Fit data to:
C(x)=βHT/(1-x)3
PVDIS on the Proton: d/u at High x
Deuteron analysis has largenuclear corrections (Yellow)
APV for the proton has no such corrections
(complementary to BONUS)
The challenge is to get statistical and systematic errors ~ 2%
)(25.0)(
)(91.0)()(
xdxu
xdxuxaP
3-month run
Fixed Target Møller Scattering
Purely leptonic reactionWeak charge of the electron:
QWe~1-4sin2W
APV me E lab (1 4sin2 W )
(sin2 W )
sin2 W
0.05(APV )
APV
1
E lab-Maximal at 90o in COM (E’=Elab/2)- Highest possible Elab with good P2I- Moderate Elab with LARGE P2I
Figure of Merit rises linearly with Elab
SLAC E158Jlab at 12 GeV
Unprecedented opportunity: The best precision at Q2<<MZ2 with the least theoretical
uncertainty until the advent of a linear collider or a neutrino factory
Design for 12 GeVE’: 3-6 GeV lab = 0.53o-0.92o APV = 40 ppb
Ibeam = 90 µA 150 cm LH2 target
• Beam systematics: steady progress (E158 Run III: 3 ppb)• Focus alleviates backgrounds: ep ep(), ep eX()• Radiation-hard integrating detector• Normalization requirements similar to other planned experiments• Cryogenics, density fluctuations and electronics will push the state- of-the-art
Toroidal spectrometer ring focus
4000 hours
(APV)=0.58 ppb
New Physics Reach
ee ~ 25 TeV
JLab Møller
ee~15TeV
LEP200
LHC
Complementary; 1-2 TeV reach
New Contact Interactions
Does Supersymmetry (SUSY) provide a candidate for dark matter?•Lightest SUSY particle (neutralino) is stable if baryon (B) and lepton (L) numbers are conserved•However, B and L need not be conserved in SUSY, leading to neutralino decay (RPV)
Kurylov, Ramsey-Musolf, Su
95% C.L.JLab 12 GeVMøller
Two Possible Hadronization Mechanisms
RG
GY
String model
Gluonbremsstrahlungmodel