Overview of Medium Energy Physics (“Cold QCD”): Presentation to the Hadron Physics Town Meeting (Presentation to the 2007 NSAC Long Range Plan Implementation.

Overview of Medium Energy Physics (“Cold QCD”): Presentation to the

Hadron Physics Town Meeting

(Presentation to the 2007 NSAC Long Range Plan Implementation Subcommittee)

Roy J. Holt

Newport Beach, CA 25 October 2012

Key questions in hadron physics

What is confinement and how is it connected with dynamical chiral symmetry breaking, the origin of more than 98% of visible mass in the Universe?

– What are the dynamics underlying elastic and transition form factors and structure functions of hadrons? How does valence quark structure affect the sea?

– Where is the missing spin in the nucleon? Are there significant contributions from gluons or valence quark orbital angular momentum?

– Can we reveal a novel landscape of nucleon substructure through measurements of new multidimensional distribution functions?

– Do gluonic excitations have a role in the spectroscopy of light mesons and baryons?

How do nuclei emerge from QCD?– What is the relation between short-range N-N correlations

and the partonic structure of nuclei?

Argonne National Laboratory

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Elastic electron scattering from a nucleon


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Cross section for scattering from a point-like object

Form factors describing nucleon shape/structure

j=<e’||e>

J=<p’||p>

Nucleon vertex:

)2(22

)2(1

', QFν

M

qiQFpp

Dirac Pauli

1990 Nobel Prize

1961 Nobel Prize

Deep inelastic scattering

Tremendous advances in electron scattering


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Unprecedented capabilities:• High Intensity• High Duty Factor• High Polarization- M. Poelker

(2012 Lawrence Award)• Large acceptance detectors• State-of-the-art polarimetry, polarized targets

Focal plane polarimeter

– Jefferson LabPolarized 3He target


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The proton form factor: Re-wrote the textbooks

Polarization measurements ) Revolutionized our knowledge

NP2010

Two-photon experiments: OLYMPUS (DESY), JLab, Novosibirsk

proton neutron

Flavor separation of proton form factors

Very different behavior for u & d quarks

Evidence for diquark correlations – axial diquark -> soft f.f.

Thanks to Craig Roberts6

Cates, de Jager, Riordan, Wojtsekhowski, PRL 106 (2011) 252003

Q4 F1q

NSAC milestone HP4 (2010) completed

Q4F2q/

Only JLab 12 GeV can access these form factors to ~10 GeV2


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Locations of the zeroes depend on the relative probability of finding scalar & axial diquarks in proton

Requires SBS Six 12-GeV experimentsPlot credit: JLab whitepaper

Proton Radius Puzzle


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rp≅0.8768(69)fm (ep atom)rp≅0.8772(46)fm (ep scattering)rp=0.84184(67)fm (μp atom)

Future sub 1% measurements: (1) ep elastic scattering at JLab (2) μp elastic scattering at PSI - 16 U.S. institutions!

(~$2 M, no contingency)

PSAS 2012 Symposium

ECT* Workshop - Nov. 2012

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X. Zhan et al, PLB 705 (2011) 59Thanks to R. Gilman, H. Gao

Hadron polarizabilities – Compton scattering

High Intensity Gamma Source (HIS)– Proton, neutron – polarized H target – Polarized 3He target (9 U.S.

institutions) MAMI (3 U.S. institutions)

– Polarized hydrogen target + Crystal Ball– Complete proton in 2014, begin neutron


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Thanks to H. Gao, H. Griesshammer, D. Phillips, W. Briscoe, R. Miskimen, B. Norum

D. Shukla, A. Nogga, D. Phillips, PRL (2007)

HIS projection

Lattice calculations Chiral perturbation theoryInterplay of “pion cloud” and

shorter distance effects

Pion polarizability– COMPASS –II (CERN)

(UIUC)

“Faraday effect”


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Parton model

Quark charge

Prob. of q in proton

Structure function

leptonic hadronic

Partonic structure of the nucleon

Three longitudinal structure functions:

EIC whitepaper

The Neutron Structure Function

Proton structure function:

Neutron structure function (isospin symmetry):

Ratio:

Focus on high x:

Three 12-GeV experiments– Proton : PVDIS and SoLID (K. Paschke)– Deuteron: radial TPC and CLAS12– 3H/3He: 3H target and existing spectrometers


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Parton model ->Upgraded JLab hasunique capability todefine the valence region

Helicity conservation

Scalar diquark

SU(6)

DSE

NSAC milestone HP14 (2018)

Thanks to C. Keppel, K. Kumar, G. Petratos

Spin Structure of the neutron – valence region

Courtesy of Z.-E. Meziani, K. Griffioen, S. Kuhn, G. Petratos


Polarized electron scattering from a polarized nucleon

Thanks to N. Makins, Z.-E. Meziani

Three 12-GeV experiments(benefits from SoLID)

Tensor charge from transversity measurements at JLab


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Thanks to A. Prokudin and Z.-E. Meziani

Tensor Charge

Collins fragmentation function from KEK-B/Belle - M. Grosse-Perdekamp (UIUC)

d benefits from SoLIDTwo 12-GeV experiments

Distribution of transversely polarized quarks inside a transversely polarized proton

Drell-Yan is the best way to measure anti-quark distributions


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What is the A dependence of antiquarks?

No model predicts dbar/ubar <1.

Longer term: Polarized FNAL, J-PARC at 50 GeV (beyond 2017)?

Experiment E906 FNAL:3 national labs, 7 U. S. universities, 3 off-shore national labs, 4 off-shore universities

Thanks to D. Geesaman, P. Reimer, J.-C. Peng

Commissioning run completed

HERMES Surprise!

Strange quark distribution

Future: COMPASS-II at CERN (2015), JLab with12 GeV (RICH)

A. Airapetian et al, PLB 666 (2008) 446

• Deep inelastic scattering with flavor tagging

• Serious discrepancy with decades of neutrino data

Thanks to H. Jackson, J.-C. Peng

Intrinsic sea?

Strange sea and LHC


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rs = ½( s + sbar)/dbar

• Sea appears to be flavor symmetric at low x, consistent with HERMES

ATLAS Collaboration,ArXiV:1203.4051 [hep-ex]

• Parton distribution uncertainties at high x feed into benchmark LHC processes

Thanks to T. LeCompte

Worldwide quest: spin structure of the nucleon

From DIS measurements ≈ 0.3G = 1.0±1.2

quark polarization q(x)first 5-flavor separation from HERMES: q ≈ 0

RHIC-spin: future charge- current measurements

gluon polarizationΔG(x)RHIC-spin, HERMES, COMPASS

orbital angular momentum L GPD’s and TMD’s

Far future: EIC

Spin budget of the proton

30%

70%

What is the origin of the proton spin?

Jets, pions, ALL

Measurement of the gluon polarization G at RHIC

D. de Florian et al,Prog. in Part. Nucl. Phys.67 (2012) 251

Dominates at high pT

Dominates at low pT

ʃdxg(x,Q2=10GeV2) = 0.13 (error?)0.05

0.2

RHIC whitepaper See E. Aschenauer’s talk for impact of 2013-14 experiments.

W production expected from RHIC runs 12+13


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B. Jacak, N. Xu, RHIC PAC 2012


• Provides an important check of SIDIS method

• No fragmentation function

• Q2=MW2 (no high twist

effects)

http://www.bnl.gov/npp/pac0612.aspThanks to E. Aschenaur

See E. Aschenauer’s talk for impact on

and

http://www.bnl.gov/npp/pac0612.asp

Is there a flavor asymmetry in the sea quark helicity distributions?

Sea quark polarization at high x

JLab 12 GeV (Hall B) Kaon detection - RICH


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Plot credit: K. Hafidi

Multidimensional parton distribution functions


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JLab whitepaper

Generalized parton distribution functions

Transverse momentum distribution functions

eg., Sivers distribution

eighteen 12-GeV experiments! Separate talk: M. Guidal

Transverse Momentum Distributions: The Sivers effect

NSAC Milestone HP13 (2015) “Test unique QCD predictions for relations between single-transverse spin phenomena in p-p scattering and those observed in deep-inelastic scattering.”

COMPASS-II, RHIC-spin, polarized FNAL

Drell-Yan

DIS

HERMES

Thanks to H. Jackson, M. Burkhardt

Polarized Drell-Yan and W production (2014+)


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COMPASS-II (2014, if upgraded)1 U. S. institution~ $0.9M NSF (large area trackers)

FNAL Polarized SeaQuest (>2017)8 U.S. institutions, 4 off-shore institutions~$10.5M including 50% contingency

PHENIX

Thanks to E. Aschenauer, W. Lorenzon, M. Liu, M. Grosse-Perdekamp

polarized

Delivered 500 pb-1

Forward upgrades -> transverse spin asymmetries

STAR

Generalized parton distributions and DVCS

e’t

(Q2)

e*

x+ξ x-ξ

H, H, E, E (x,ξ,t)~~

p p’

Vector: H (x,ξ,t)

Tensor: E (x,ξ,t)

Axial-Vector: H (x,ξ,t)

Pseudoscalar: E (x,ξ,t)

~

~

Quark angular momentum (Ji’s sum rule)

X. Ji, Phy.Rev.Lett.78,610(1997)

( H(x,,t=0) + E(x,,t=0) ) x dx = JJquarkquark-1

1=1/2 =1/2 LLzz

Hq(x,0,0) = q(x)q(x) Hq(x,0,0) = q(x)q(x)~

1

1

dx Hq(x,,t) = FFqq11

(t)(t) dx Eq(x,,t) = FFqq22

(t)(t)

1

1

Forward limit (t t →0→0, , →0→0))

Sum rulesSum rules

A. Radyushkin,PRD 56 (1996) 5524

C. Munoz Comacho et al,PRL 97 (2006) 262002 ;F. X. Girod et al, PRL 100 (2008)162002.

Extraction of quark total angular momentum

NSAC milestones HP11 (2012), HP9 (2014)

• DVCS is the “golden channel”:* + N -> + N’

• “Lattice + experiment provides a much greater constraint on GPDs than from either alone.” - J. Negele

• Major program for JLab 12 GeV, COMPASS-II, EICPlot credit: JLab whitepaper

DVCS measurements and imaging


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Thanks to Z.-E. Meziani, JLab whitepaper

A new form of matter: Matter formed from the force field (gluons):

• meson spin

• intrinsic parity

• charge conjugation

Conventional mesons:

K. Juge et al, nucl-th:030711

separate talk: J. Dudek Thanks to C. Meyer, C. D. Roberts

“Valence” gluon can add one unit of angular momentum.

Search for exotic hybrid mesons at the 12-GeV JLab


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MR

Hybrids are predicted by modern QCD treatments: DSE, lattice


Complementary work: GSI (PANDA) : antiproton-proton annihilation in charmonium region (2017-) (Northwestern U.)

BES-III: electron-positron annihilation in charmonium region – also decays to light quark bound states(Indiana U.)

Plot credit: NP2010

Two 12-GeV JLab experiments

Thanks to K. Seth, M. Shepherd, J. Dudek

Baryon resonances – JLab Physics Analysis Center


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Kamano, Nakamura, Lee et al., 2012

NSAC milestones HP3 (2009) completed, HP7 (2012)

Future: J-PARC, Mainz 6 U. S. institutions

Thanks to K. Hicks, W. Briscoe, M. Pennington, T.-S. H. Lee

• Previous (,2) data in the N* mass range are all from 1970’s bubble chambers!

• New Lattice calculations: arXiv:1201.2349 N* resonances and exotic baryons.

Coupled channels dynamics are essential!

Baryon spectrum from EBAC & Bonn-Ga (PDG12)

A look at quarks in the nucleus: the EMC effect

EMC effect discovered 1982 (H. Montgomery et al.), remains a mystery today

Scattering from quarks in a nucleus is not just a superposition of scattering from quarks in nucleons

– Dependence on nuclear density, short range correlations, flavor, spin, isospin?


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SLAC E-139, 1984, J. Gomez et al.J. Seeley et al, PRL 103 (2009)

EMC effect and short range N-N interaction

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EMC effect is correlated with short range N-N interaction – L. Weinstein et al, PRL 106, 052301 (2011) , J. Arrington et al, arXiv:1206.6343

Flavor, isospin and spin dependence of EMC effect? JLab@12, Drell-Yan, MINERvA

Plot credit: JLab whitepaper

N. Fomin et al, PRL 108, 092502 (2012)

SRC Scaling factors xB ≥ 1.5

Four JLab 12 GeV experiments

MINERA Main Injector ExpeRiment ν-A

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MINERvA is studying A dependence of neutrino interactions in unprecedented detail, with He, C, Scintillator (CH), H2O, Fe, Pb targets.

Uses high intensity NuMI Beamline at FNAL with MINOS near detector as muon spectrometer

Nuclear physics goals High precision measurement of the axial form factor to high Q2 and search for A

dependence of form factor Studies of quark-hadron duality in neutrino interactions, complementing Jlab Studying partonic nuclear effects with neutrino interactions Precision cross section measurements and studies of final states

Schedule Low E ν and anti-ν (average E ~4 GeV) 11/09-4/12

~1.7 Million ν CC interactions and 250 K anti-ν CC interactions on scintillator, ~300 K ν CC interactions on Fe and Pb

Medium E ν (avg E ~8 GeV) spring 2013 to about 2019 MEP Participation

Hampton, Rutgers – PMT detector construction and testing, scintillator plane construction. He target funded by MEP

Slide credit: R. Ransome

Hadronization and quark propagation in nuclear matter

Production length Parton energy loss Formation length Color transparency Hadron multiplicity pT broadening

12 GeV Anticipated Data: 1035 cm-2s-1

CEBAF @ 12 GeV + CLAS12: ideal facility to study light quark hadronization:

)(

)(),,,( 22

D

AQpzR

hDIS

hDIS

T

What governs the transition of quarks and gluons into pions and nucleons? NSAC 2007

W. Brooks, K. Hafidi, K. Joo et al.

The EIC (>2020)


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Source: EIC whitepaper

Gluon saturation

Gluon and sea quark polarization

Gluon imaging

Quark propagation

Sea quark imaging

2020 and beyond: Electron Ion Collider

“We recommend the allocation of resources to develop accelerator and detector technology necessary to lay the foundation for a polarized Electron-Ion Collider.” NSAC LRP 2007

Brookhaven National LabJefferson Lab

Unique: high-luminosity with polarized electrons, nuclear and polarized ion beams

Non-JLab, non-RHIC cold-QCD experiments


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*Expected

Program Contact Status Lab# U.S. MEPInstitutions

Education – # U.S. MEP postdocs, grad. students, undergrads

n polarizability, GDH, few-body

H. Gao Ongoing HIS 9 2, 5, 3

Drell-YanD. Geesaman,

P. ReimerOngoing FNAL 8 7, 7, 4

COMPASS-IIM. Grosse-Perdekamp

Ongoing CERN 1 1, 2, 4

N polarizability R. Miskimen Ongoing Mainz 3 2, 3, 1

Baryon resonances W. Briscoe Ongoing Mainz 6 1, 3, 6

MINERvA R. Ransome Ongoing FNAL 2 2, 2, 2

N polarizability, GDH, few-body, Bethe-Heitler

B. Norum Ongoing HiS 4 2, 1, 2

OLYMPUS R. Milner Ongoing DESY 4 3, 6, 6

HERMES H. Jackson Ongoing DESY 3 1, 4, 1

BES-III M. Shepherd Ongoing BES 1 1 ,2, 0

Threshold pion photoproduction

A. Bernstein Ongoing Mainz 3 1, 0, 0

Radiative pion production

B. Norum New Mainz 2 0.2, 0, 0

Polarized Drell-Yan

W. Lorenzon New FNAL 8 0.5, 0.5, 3

N polarizability R. Miskimen New HIS 4 0, 0, 1

Proton radius R. Gilman New PSI 16 1, 0, 0

Baryon resonances K. Hicks New J-PARC 6 2, 5, 0*

Charmed mesons K. Seth New GSI 1 1, 2, 0

Static- Electromagnetic-Polarizabilities of the proton and neutron

Spin Polarizabilities of the proton Spin Structure and the Gerasimov-Drell-

Hearn (GDH) Sum Rule Measurements

Hadron program at HIGS (next 3 years)

Chiral Dynamics using photopion production Spin Polarizabilities of the neutron

Future program at HIGS (beyond 3 years)

Thanks to C. Howell

Concluding statement

Understanding hadrons will be one of nuclear physics’ greatest contributions to science

New 21st century tools have positioned us well for the next decade: – JLab 12 GeV, RHIC - Major U.S. facilities lead the world– FNAL – MI, CERN COMPASS-II, HIS, Mainz, J-PARC, FAIR provide

targeted experiments that complement the central program– Far future: EIC

We are camped on one of the most interesting frontiers in science


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Many thanks to


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M. AhmedE. AschenauerJ. ArringtonT. BarnesD. BeckW. BriscoeM. BurkhardtG. CatesA. DesphandeC. DjalaliE. DownieR. EntC. GagliardiH. GaoD. GeesamanR. GilmanH. GriesshammerM. Grosse-PerdekampK. HafidiK. HicksC. HowellB. Jacak

Helpful documents:

•NP2010 Report

•NSAC 2007 Long Range Plan

•Whitepaper drafts:JLab 12 GeVThe Case for Continuing RHIC

OperationsElectron Ion Collider

•JLab12, RHIC, COMPASS-II proposals

•STAR and PHENIX decadal plans

•NSAC Performance Measures 2008

J.-C. PengM. PenningtonD. PhillipsG. PetratosJ. QiuR. RansomeP. ReimerC. RobertsJ. RubinK. SethM. ShepherdM. StratmannB. SurrowS. VigdorW. VogelsangH. WellerR. WiringaB. WojtsekhowskiN. Xu

H. JacksonK. JooB. KeisterC. KeppelW. KorschK. KumarT.-S. H. LeeM. LiuW. LorenzonT. LeCompteN. MakinsC. MeyerZ.-E. MezianiR. McKeownR. MilnerR. MiskimenH. MontgomeryJ. NagleB. NorumK. OrginosK. Paschke

Overview of Medium Energy Physics (“Cold QCD”): Presentation to the Hadron Physics Town Meeting (Presentation to the 2007 NSAC Long Range Plan Implementation.

Documents

inelastic scattering

gao slide

ep elastic scattering

jlab whitepaper slide

completed q4f2qq4f2q

object form factors

transition form factors

fm ep atom r p