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CLAS Hadron Spectroscopy. Working Group Meeting Report, CLAS12 2nd European Workshop/ CLAS Collaboration Meeting, March 2011. Analyses Under Working-group Review - 1

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clas hadron spectroscopy

CLAS Hadron Spectroscopy

Working Group Meeting Report,

CLAS12 2nd European Workshop/

CLAS Collaboration Meeting,

March 2011


Analyses Under Working-group Review - 1

Measurement of the Lineshape, Differential Photoproduction Cross Section, Spin and Parity of the Lambda(1405) Using CLAS at Jefferson Lab

Contact persons: Reinhard Schumacher, Kei MoriyaAnalysis Review Committee: Paul Eugenio (chair), Raffaella De Vita, Mac Mestayer

Committee formed November 8, 2010

First round comments; awaiting author response

Photoproduction of the phi(1020) with linearly polarized photons from the proton

Contact persons: Julian Salamanca and Phil ColeAnalysis Review Committee: Bryan McKinnon (chair), PawelNadel-Turonski, Mike Wood Committee formed June 10, 2010

Second round comments; awaiting author response

Differential cross sections and SDME for phi(1020) photoproduction from g11

Contact persons (CMU): BiplabDey and Curtis MeyerContact persons (ODU): HeghineSeradaryan and MoskovAmarianAnalysis Review Committee: Lei Guo (chair), RaffaelllaDeVita, Michael Dugger, Valery Kubarovsky

Committee formed July 20, 2010

Awaiting confirmation of consistent results


Analyses Under Working-group Review – 2

Review #4709539: "Photo-production of Σ∗+(1385) with CLAS" (1st round ended on March 4, 2011)

Initiated by:David IrelandReview type: AnalysisStatus:

Contact author:GagikGavalianExperiment/Working group: g11/HSCommittee: Kenneth Hicks (Chair), Ralf Gothe , Eugene PasyukReview deadline: March 4, 2011

Pending Analyses Reviews

Photoproductionof Lambda1520 Hyperon off Protons and Neutrons in Deuterium" with eg3 data.

Contact author: ZhiwenZhao

Awaiting formation of committee

ad hoc reviews
Ad-Hoc Reviews

Review #8061056: "Upper limits for photoproduction cross section for the Φ--(1860) pentaquark state" (1st round ended on January 31, 2011)

Initiated by:HovanesEgiyanReview type: Ad-hocStatus:1st round endedContact author:HovanesEgiyanExperiment/Working group: eg3/HSCommittee:Reinhard Schumacher (Chair), Angela Biselli , Gerard GilfoyleReview deadline: January 31, 2011

pac proposals
PAC Proposals

Meson Spectroscopy with low Q2 electron scattering in CLAS12

Contact persons: Marco Battaglieri and Raffaella De VitaAnalysis Review Committee: Volker Crede (chair), ChadenDjalili, HovanesEgiyan

PAC result: A-

collaboration wide review
Collaboration-wide review

Review #5573944: "Electromagnetic decay of the Sigma*0 to Lambda gamma" (Ended on March 1, 2011)

Initiated by:Marco RipaniReview type: Collaboration-wideStatus:EndedContact author:Kenneth HicksExperiment/Working group: g11/HSReview deadline: March 1, 2011



14:15 Opening comments - Dave Ireland

14:20Measuring the G polarisation observable for KΛ photoproduction from g9a - Stuart Fegan

14:45Search for Missing Resonances in γp -> K Λ using Circularly Polarized Photons on a Polarized Target - Liam Casey

15:10Electroproduction of hybrid 1-+ mesons - Samuel Wallon

15:35OZI and G-parity violating decays of η' and φ mesons - MoskovAmaryan

double polarization observables in g p k l using circularly polarized photons incident on frost g9a

Double Polarization Observables in gp→K+L using Circularly Polarized Photons incident on FROST (g9a)

Liam Casey

Catholic University of America

CLAS 12 European Meeting

Hadron Spectroscopy Group

missing mass m x g p k x
Missing Mass M(X) (gp→K+X)

Kaon vertex distribution determines the target of event origin.

The missing mass off the Kaon can be used to find Λ and Σ signals in both targets.

consistency recoil polarization
Consistency – Recoil Polarization

1.4 GeV

1.5 GeV

The recoil polarization P shows good agreement with g11 data across most of the energy range. These are typical bins. Here I calculate P in an integrated manner taking the asymmetry in protons falling above and below the reaction plane.

Technically, recoil asymmetry from carbon should be subtracted.

g1c to g1c comparison
G1C to G1C Comparison

1.4 GeV

Values of g1c analysis are rotated to primed coordinate system according to the rubric of Sandorfi.

1.5 GeV

A. M. Sandorfi et al., arXiv:1010.455v1 [nucl-th] 21 Oct 2010

helicity asymmetry e
Helicity Asymmetry E

E plotted for the missing D13 relevant 1.5 GeV photon energy bin

Solid blue line shows kaon-MAID Model of T. Mart. Dashed orange line is the model of B. Saghai, which includes hyperonic resonances in place of D13 and the dot-dash magenta line is the SAID based PWA of GWU.

Dilution calculated by angular bin, PT and Pγ for each kinematic bin.

polarization transfer l x and l z
Polarization Transfer Lx' and Lz'

1.5 GeV

1.5 GeV

Lx‘ and Lz’ are calculated in the same manner as the beam-recoil polarization transfer with the target polarization magnitude and direction replacing the beam circular polarization and helicity.


Rare Decays of Light Mesons in CLAS.

Preliminary Results.

M.Amaryan, G.Gavalian, C.Nepali

Old Dominion University

Norfolk, VA

CLAS Collaboration Meeting

Paris, March 10, 2011


Missing Mass





We use g11 Data:

3 charged track events identified as a proton and two oppositely charged pions


First Observation of G-Parity

Violating Decay of φ Meson


PDG Exp. limit Br<1.8x10-5



M=1.021 GeV

σ = 0.005 GeV

Theory prediction:

Br( ) ~3x10-7

(I.J.M.Phys. A, Vol.7, No. 20(1992), 4825)


OZI Rule Violating Decay

of ϕ meson in photoproduction







Very Different from e+e-



First Observation of rare EM decay of η meson





(Not seen before,

an upper limit is quoted

in PDG.)