MesonMeson (pseudoscalar and vector) PhotoproductionPhotoproduction (polarized and unpolarized γs)

offoff (unpolarized and polarized) neutronsneutrons(A Very Brief Overview on g10, g13, and HD)

N* Analysis Workshop -- Jefferson Lab

Phil ColeIdaho State UniversityNovember 4, 2006

Goals of the WorkshopStepsSteps towards a coherent analysis of CLAS and world data in the extraction of N* parameters in coordination with theoretical approaches.

beam-, target-, and recoil-polarization observables within the context of g10, g13, and HD (γ + n). (BES and CLAS)

White PaperWhite Paper to outline the importance of the N* effort for the NSAC Long-Range Plan with adequate representation of

JLab N* Program with CLASExcited Baryon Analysis Center (EBAC)PIRE: Nucleon Resonance Studies –

A New Collaboration between the U.S. and the P.R.China.

Outlook• complete (over-)determination of KΛ amplitude• almost complete sets for πN, ππN, KΣ, … ηp, ωN

FROST program to run in 2007HD program ready to run in 2009

consistent analyses (CC): • extract parameters

for “known” resonances• potential to find any find any

“missing” resonance“missing” resonance

expose a new richexpose a new richspectroscopyspectroscopy

simultaneous data taking:common systematics

Proposed reactions on the deuteron (g13 & HD)g13 & HD)γN → N* → KYγn → K0Λ→ π+π-π-pγn → K+Σ– → K+π–nγn → K0Σ0 → K0Λγ → π+π-π-pγγp → K+Σ0 → K+Λγ → K+π-pγγp → K0Σ+ → π+π-π0p / π+π-π+nγp → K+Λ→ K+π–p

γn → N* → KY* and γn → N* → K*Y channels includeγn → K+Σ–(1385) → K+π-Λ→ K+π-π-pγn → K*0Λ→ K+π-π-p

D13(1900) / D13(2080)

isotriplet

importantfor rescattering

A Focus on Hyperon Production. Need CAAs for other channels

Polarization observablesPolarization observables

4 complex amplitudes≥ 8 measurements required to completely determine the amplitudes

γp: all 4 combinations of beam (lin,circ) and target (long,trans)γn: 2 combinations of beam (lin,circ) and long.pol. targetfor Λ, Σ0,+ additionally recoil polar. complete setall observables as functions of √s and cosθuse algebraic relations to check for systematics

from CLAS g1, g2, g8, g13g13, (g10,g11) data

Relations among the observablesR.A. Adelseck and B. Saghai, Phys. Rev. C 42, 108 (1990):

Beam + RecoilCx’

2 + Cz’2 + Ox’

2 + Oz’2 = 1 + T2 - P2 - Σ2

Cz'Ox' - Cx'Oz' = T – PΣ

Beam + TargetE2 + F2 + G2 + H2 = 1 + P2 - Σ2 - T2

FG - EH = P – ΣT

Target + RecoilTx’

2 + Tz’2 + Lx’

2 + Lz’2 = 1 + Σ2 - P2 - T2

Tx’Lz’ - Tz’Lx’ = Σ – PT

What characteristics should an experiment have to provide the best constraints for coupled-channels calculations?

Wide kinematic coverage

Small uncertainties

Several polarization observables

Beam asymmetry from JLab (g8a) and Spring-8Calculations by Ireland, Janssen, Ryckebusch et al.

γp→K+Λ

Sensitivity of polarization observables in the K0Λ channel to the presence of the missing D13(1900) resonance

C. Bennhold and A. Waluyo (2006): Full calculation and D13(1900) excluded.

From g13 Presentation to PAC30 (Pawel Nadel-Turonski)

expected sensitivityexpected sensitivity

γn→K0Λ EEγγ=1.55 =1.55 GeVGeV, W=1.95 , W=1.95 GeVGeV

B.JuliB.Juliáá--DiDiáázz, T., T.--S.H. Lee (preliminary)S.H. Lee (preliminary)

|| expected dataexpected data

g10: unpolarized γs on deuterium

New experiment was approved by JLAB PAC24, June 2003. Run took place March – May 2004.

Goals – search for the Θ+ pentaquark in the γd interactions : increase published statistics by x10;Θ+ mass determination with 2 MeV accuracy;

Run conditions: Tagged photons in the energy range from 0.8 to 3.59 GeV; Target – 24 cm long liquid deuterium; Trigger – two charged particles in CLAS.

Two settings of CLAS toroidal magnet: IT=2250 A and 3375 A. At each setting integrated luminosity ~25pb-1 (10 times higher than in published deuterium data).

Special measurements for Hall B tagged photon beam energy calibration.

γd pK+K-(n)

d

γ Θ+n

K+

K-p

K-p

n

S. Niccolai, M. Mirazita, P. Rossi, K. Hicks, B. McKinnon, N. Baltzell, D.S. Carman, T. Mibe,S. Stepanyan, D. Tedeschi + CLAS Collaboration. PRL 97, 032001 (2006).

γd Λ0K+n

B. McKinnon, K. Hicks,S. Niccolai, M. Mirazita, P. Rossi, N. Baltzell, D.S. Carman, T. Mibe, S. Stepanyan, D. Tedeschi + CLAS Collaboration. PRL 96, 212001 (2006).

New Analyses: Coherent phi-meson photoproduction (T. Mibe)CAA: Kaon Photoproduction (P. Nadel-Turonski)

Experiments with Linearly Polarized Photons at CLAS

The future The future -- linearly polarized photonslinearly polarized photonsg8b

Analysis of many channels will begin soon.

High statistics > 10 billion events

High photon polarization from 1.3 – 2.1GeV.

Prelim analysis of γp → Nπ on a few runs with rough calibration. (M. Dugger ASU)

• Pγ estimated at 0.8

• Blue line is SAID prediction

• Data with statistical errors (no systematic)

preliminary

HyperonHyperon production on deuterons production on deuterons AA--rated at August 2006 PAC. rated at August 2006 PAC. (P. (P. TuronskiTuronski, E, E--0606--103)103)

Will use circularly and linearly polarized photons.Will use circularly and linearly polarized photons.

Access to neutron channels.Access to neutron channels.

Repeat g8b Repeat g8b kaonkaon channels on proton in medium. channels on proton in medium. Look for FSI effects.Look for FSI effects.

Kaon photoproduction on the deuteron using polarized photons

g13 E-06-103

P. Nadel-Turonski, B.L. Berman, Y. Ilieva, A. Tkabladze,C. Bennhold, G. Feldman, E. Munevar, A. Waluyo (GWU),D.G. Ireland, K. Livingston, B. McKinnon, D. Protopopescu (Glasgow),F.J. Klein, J. Santoro (CUA),V. Burkert, L. Guo, J.-M. Laget, S. Stepanyan (JLab),E. Pasyuk (ASU), I. Niculescu (JMU), S. A. Pereira (INFN),P.L. Cole, D.S. Dale, T.A. Forest (ISU),P. Mattione, G. Mutchler (Rice),+ The CLAS Collaboration

Summary for g13 (for PAC30 Presentation)

We propose to measureγd → N*(N) → KY(N) channelsusing linearly and circularly polarized photons and an LD2 targetwith high statistics, good kinematic coverage, and low background.

The main goal is to find evidence for or against the existence of “missing” nucleon resonances.

Our approach is based on coupled-channels analysis, required for reliable N* extraction.

High-statistics studies of Y-N, Y*-N, and K-N rescattering will reduce the systematic uncertainties and provide insight into the hyperon –nucleon interaction.

The experiment is ready to run. [g13 began on 27 Oct 2006]

Experiments with Linearly Polarized Photons at CLAS

The future The future –– polarized photons + polarized targetspolarized photons + polarized targets

FROST (Frozen Spin Polarized Target)Longitudinal and transverse target polarization

Combine with circularly and linearly polarized photons

Scheduled for Feb. 2007

Double polarization observables

Several proposals (http://clasweb.jlab.org/frost)

Transverse holding coil

(C,Keith, M. Seely)

Combined HD polarized target (LEGS).Target is polarized at LEGS and brought to JLab by truck. (Long relaxation time)

Simultaneous measurement on polarized p and n

Combine with circularly and linearly polarized photons

A-Rated at Aug 2006 PAC (A. Sandorfi and F.J. Klein, E-06-101).

0.7 < Eγ < 2.5 GeV

“ … and a complete determination of γ n → K0 Λ amplitude”

γn→π-pIdentification of γn→π-p

cut on cut on missing missing pspectator

miss. momentum and miss. momentum and coplanaritycoplanarity after the cutafter the cut

HD: 3 polar. observ. for π-pstatistics ±2-5%systematics ±4-6%(improved statistics and systematics through measurement of Σ in g13)

E06E06--101: 101: 00-- photophoto--production from polarized production from polarized nn inincomplete determination of the complete determination of the γγ n n →Κ→Κ00 ΛΛ amplitudeamplitude

• 1st large data set for γ n → πN, ππN, KΛ, KΣ• 1st complete (over-)determination in pseudoscalar photoproduction

γn → Κ0Λ - 14 obsv: σ, Σ, E, G, P, T, Cx, Cz, Ox, Oz, Lx, Lz, Tx, Tz

E (BeamE (Beam--Target) Target) CCzz (Beam(Beam--Recoil) Recoil) LLxx ((TargetTarget--Recoil)Recoil)

eg:

rH ⋅

rD

γn→Κ0Λ, W=1.95GeV no π-cloudno coupled-chno D13 (1910)

→ access physics underlying baryons

→ expose “missing resonances” ⇔ N* quark structure

→ access physics underlying baryons

→ expose “missing resonances” ⇔ N* quark structure

expected dataexpected data

A Few Experimental Details

Coherent Bremsstrahlung Facility. Commissioned by g8a/g8bTo be used by g13, FROST, and HD

FROST target (Eugene Pasyuk’s talk)

HD target.

Experiments with Linearly Polarized Photons at CLAS

The coherent bremsstrahlung facility at CLAS

Requirements for coherent brem

Low emittance, stable beam

High quality thin crystal

Collimation < 0.5 characteristic angle

Polarimetry022

044066

Goniometerand

Diamond

Photon Tagger

Active collimator

PairSpectrometer

Polarimeter

CLAS detector

BeamProfiler

23m LH2 target

HD target

target: Ø25mm x 50mm3g of solid H-D compositedensity: 0.147 g/cm3

2050 cooling wires (Al) Ø50µmPV(D)~40%, P(H)~40% or PV(D)~0%, P(H)~80%

InIn--BeamBeam--Cryostat for CLASCryostat for CLAS

additional empty cell downstream:subtraction of Al background

Experiment and Theory

Experimentcross section,

spin observables

TheoryLQCD,

quark models,QCD sum rules,

…

Reaction Theorydynamical frameworks

Amplitude analysis→multipole ampl.,→phase shifts

σ,dσ/dΩ(single) Σy,P,T[ Σp, T20, T21,T22]

(beam-target) E, F, G, H,(beam-recoil) Cx,Cz, Ox,Oz,(target-recoil) Lx,Lz, Tx,Tz,[(beam/target-VM) CBV, CTV, CBTV]

PWA: single energysolution CC: resonance param.

extraction

Coupled-channels picture of resonance excitation

πNππN

γN → N* → ηNKΛKΣ

The same N* resonance must be found in different reaction channels in a consistent way!

TπΝ→πΝ TηΝ→πΝ TγΝ→πΝ TρΝ→πΝ TσΝ→πΝ TΚΛ→πΝ TΚΣ→πΝ

TπΝ→ηΝ TηΝ→ηΝ TγΝ−>ηΝ TρΝ→ηΝ TσΝ→ηΝ TΚΛ→ηΝ TΚΣ→ηΝ

TπΝ→γΝ TηΝ→γΝ TγΝ→γΝ TρΝ→γΝ TσΝ→γΝ TΚΛ→γΝ TΚΣ−>γΝ

TπΝ→ρΝ TηΝ→ρΝ TγΝ→ρΝ TρΝ→ρΝ TσΝ→ρΝ TΚΛ→ρΝ TΚΣ→ρΝ

TπΝ→σΝ TηΝ→σΝ TγΝ→σΝ TρΝ→σΝ TσΝ→σΝ TΚΛ→σΝ TΚΣ→σΝ

TπΝ→ΚΛ TηΝ→ΚΛ TγΝ→ΚΛ TρΝ→ΚΛ TσΝ→ΚΛ TΚΛ→ΚΛ TΚΣ→ΚΛ

TπΝ→ΚΣ TηΝ→ΚΣ TγΝ→ΚΣ TρΝ→ΚΣ TσΝ→ΚΣ TΚΛ→ΚΣ TΚΣ→ΚΣ

T=

Experiments with Linearly Polarized Photons at CLAS

Motivation – vector meson production

Extraction of spin density matrix elementsCalculations for ρ0 decay (Roberts)

26 resonances

N3/2+(1910)

26 – N3/2+(1910)

Helicity reference frame

Linear polarization gives access to 6 more matrix elements than unpolarized data.

g8 aims to do this for ρ0, Φ and ω.

Density Matrix Elements and PWADensity Matrix Elements are formed of bilinear combinations of Helicity Amplitudes.

Helicity amplitudes can be decomposed into partial waves.

Combinations of the helicity amplitudes will serve as constraints for the PWA fits.

Build upon IHEP’s PWA approach of B.S. Zou

Partnership for International Research and EducationA new collaboration between the U.S. and the P.R.C

Experimental Research Program

Discovery potential: Hunt for nucleon resonances with BES and hone in on the dynamic structure with CLAS.

The low-background nucleon resonance production in J/Ψ baryon-antibaryondecays is isospin selective and probes the on-shell structure of the hadrons; offering a unique sensitivity and thus guidance in the search for resonance signals.

Beam-, target-, and recoil-polarization observables and transition form factors accessible at JLab will provide hitherto inaccessible detailed information about resonance properties.

Measurements with the Beijing Spectrometer (BES) at Beijing Electron Positron Collider (BEPC) complements those with CEBAF Large Acceptance Spectrometer (CLAS) at Thomas Jefferson National Accelerator Facility (JLab).

Nucleon Resonance Analysis ProgramThis PIRE program will provide the framework to explore the relation between IHEP´s PWA and EBAC´s dynamical analyses.

The analysis of both BES and JLab data with very different and unique background contributions, will be indispensable for us to develop refined theoretical tools to extract complementary resonance production amplitudes.

These empirical amplitudes also contribute important information to the dynamical coupled-channel analyses, which are being carried out at Excited Baryon Analysis Center (EBAC) at JLab, aiming at developing theoretical interpretations of the extracted nucleon resonance parameters in terms of QCD-inspired hadron models and Lattice QCD.

NSF PIRE: Nucleon Resonance StudiesA New Collaboration between the U.S. and the P.R.C.

Pre-proposal submitted just this past Monday (30 October).

R.W. Gothe, P.L. Cole, S. Strauch, V. Burkert, T.-S. H. Lee, (USA) Q. Zhao, B.S. Zou, B.T. Hu, C.F. Qiao, and X.Q. Li. (PRC)

U.S./P.R.C. University of South Carolina, Idaho State Univ., JLab, Argonne Nat’l Lab, Institute of High Energy Physics, Lanzho Univ., Nankai Univ., Graduate School of the Chinese Academy of Science.

Collaboration of Theorists and ExperimentalistsFive Year $2.5 Million Request (upon invitation to submit full proposal)

PWA Workshop on Jan. 25-26, 2007 in Beijing.

Letters of Endorsement (T.D. Lee, HeSheng Chen, Tony Thomas)

Thanks to

Ken Livingston (g8b)Stepan Stepanyan (g10)Pawel Nadel-Turonski (g13)Franz Klein (FROST + HD)

for providing me their slides

Extra Slides

Polarization observables in K photoproductionSingle-polarization observables

Cross section (σ0)Recoil polarization (P)Beam asymmetry (Σ)Target asymmetry (T)

Double-polarization observablesBeam + Recoil ( Cx’,Cz’,Ox’,Oz’ )Beam + Target ( E, F, G, H )Recoil + Target ( Tx’, Tz’, Lx’, Lz‘ )

No observable requires triple polarization

The first 8 can be measured without a polarized targetT is accessed as a double-polarization observable

16 observables in total - but they are not independent!

Experiments with Linearly Polarized Photons at CLAS

The future – a complete measurement

Observables in pseudoscalar meson production (Barker, Donnachie & Storrow Nucl Phys B95 (1975) )

16 observables (red): 1 x unpol, 3 x single pol, 3 x BT, 3 x TR, 3 x BR

These are combinations of the 4 complex amplitudes which describe the reaction.

Non-independent. ie we don’t need to measure them all.

Require >= 8 observables from 3 classes (classes = single, BT, TR, BR)

CLAS will have: linearly + circulary polarized photons, longitudinal + transverse target polarization, recoil polarization (hyperons are self analysing)

A complete measurement is in our sights.

PhotoproductionPhotoproduction by linearly polarized photonsby linearly polarized photons

Decay Plane || γ

for natural parity exchange [P = +(-1)J]

PomeronPomeron, Scalar mesons), Scalar mesons)Polarizationvector of γ

ππ++

ππ--

ππ++

ππ--

Decay Plane γfor unnatural parity exchange

[P = --(-1)J ] ((PseudoscalarPseudoscalar mesons)mesons)

In the In the ρρ00 rest frame (e.g. rest frame (e.g. HelicityHelicity frame)frame)

Thus accessing the Thus accessing the Decay Angular DistributionDecay Angular Distribution

of the of the ρρ0 0 vector mesonvector mesonprovides a measure on the degree of provides a measure on the degree of •• natural parity exchangenatural parity exchange•• unnatural parity exchangeunnatural parity exchange

e.g. JP = 0+, 1-, 2+, 3- …

e.g. JP = 0-, 1+, 2-, 3+ …

Statistical uncertainties for the K0Λ channel

Linear polarization: 33 days, Circular polarization: 15 days.Other channels have somewhat larger statistical uncertainties.

γn→K0Σ0, K+Σ-

HD: 13 polar. observ. for K0Λ4-5 polar. observ for K0Σ0, K+Σ-

statistics ±8-12% (<20% for Σ-)systematics ±5-7% (beam, target, P, Σ)

±6-10% E, G, Cx,z, Ox,z, Lx,z, Tx,z

γγnn→→KK++ΣΣ--γγnn→→KK00ΣΣ00

Tagged and Collimated Tagged and Collimated γγ beam on targetbeam on target→

Photon Polarizationexceeds 90% in the peak

Tightly and Actively Collimated: ~½ of a characteristic angle (Collimator subtends 44 µradians)

MMMM22

((γγ+D)+D)

MMMM22 ((γγ+n)+n)γγ n(p)→ Κ0 Λ(p)

→ π+π–pπ–(p)

γγ n(p)n(p)→→ ΚΚ00 ΣΣ00 (p)(p)→→ ππ++ππ––ppππ––((γγ p)p)

E06E06--101101: : + + frozen-spin in CLASin CLASr

H ⋅rD

•• clean channelclean channel--separation;separation;very low backgroundsvery low backgrounds

⇒⇒ factors of > 20 reduction infactors of > 20 reduction inbeambeam--time over other targetstime over other targets

•• high nucleon polarizations high nucleon polarizations •• inin--beam lifetimes > yearbeam lifetimes > year

rγ