photoproduction and decays of pseudoscalar mesons in clas moskov amaryan old dominion university...
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![Page 1: Photoproduction and Decays of Pseudoscalar Mesons in CLAS Moskov Amaryan Old Dominion University Norfolk, Virginia, USA M.Amaryan, University of Bochum,](https://reader036.vdocument.in/reader036/viewer/2022062518/56649f585503460f94c7e39f/html5/thumbnails/1.jpg)
M.Amaryan, University of Bochum, December 6, 2011
Photoproduction and Decays of Pseudoscalar Mesons in CLAS
Moskov Amaryan Old Dominion University Norfolk, Virginia, USA
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M.Amaryan, University of Bochum, December 6, 2011
Outline
-CLAS setup at JLAB
-Classification of Mesons
-Hadronic decays
-Dalitz decays
-Radiative decays
-Summary
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M.Amaryan, University of Bochum, December 6, 2011
Emax ~ 6 GeV
Imax ~ 200 mA
Duty Factor ~ 100% sE/E ~ 2.5
10-5
Beam P ~ 80%Eg(tagged) ~ 0.8- 5.5 GeV
CLAS
JLab Site: The 6 GeV CW Electron Accelerator
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M.Amaryan, University of Bochum, December 6, 2011
The CLAS Photon Tagger
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M.Amaryan, University of Bochum, December 6, 2011
CEBAF Large Acceptance Spectrometer
Liquid D2 (H2)target + g start counter; e minitorus
Drift chambersargon/CO2 gas, 35,000 cells
Electromagnetic calorimetersLead/scintillator, 1296 PMTs
Torus magnet6 superconducting coils
Gas Cherenkov counterse/p separation, 216 PMTs
Time-of-flight countersplastic scintillators, 684 PMTs
Large angle calorimetersLead/scintillator, 512 PMTs
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M.Amaryan, University of Bochum, December 6, 2011
Horizontal cut through the CLAS detector
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M.Amaryan, University of Bochum, December 6, 2011
(Reminder)
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M.Amaryan, University of Bochum, December 6, 2011
Type S L P J JP
Pseudscalar mesons
0 0 - 0 0-
Axial vector mesons
0 1 + 1 1+
Vector mesons 1 0 - 1 1-
Scalar mesons 1 1 + 0 0+
Tensor mesons 1 1 + 2 2+
Meson Families
J=L+S
P=(-1)L+1
C=(-1)L+S
G=(-1)L+S+I
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M.Amaryan, University of Bochum, December 6, 2011
In the SU(3) Group Theory Language
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M.Amaryan, University of Bochum, December 6, 2011
OUTLINE - Photoproduction of Pseudoscalar Mesons with CLAS
Radiative Decays
Hadronic Decays
Also Vector Mesons:
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M.Amaryan, University of Bochum, December 6, 2011
Missing Mass Distribution
gp pX
Single charged track events identified as a proton
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M.Amaryan, University of Bochum, December 6, 2011
Missing Mass
3 charged track events identified as a proton, π+ and π-
π0
η
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M.Amaryan, University of Bochum, December 6, 2011
OZI allowed OZI suppressed
Okubo-Zweig-Iizuka Rule
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M.Amaryan, University of Bochum, December 6, 2011
ω-ϕ Interference in e+e- annihilation
M.N.Achasovhep-ex/0604051
It depends on production and decay amplitudes of interfering resonances as well as on their relative phases.
How would it look like in photoproduction?
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M.Amaryan, University of Bochum, December 6, 2011
OZI Rule Violating Decay of ϕ meson in photoproduction
ω
η
ϕη‘
η‘ ϕ
γ+p = pπ+π-π0
(~2M events)
Hadronic decay
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M.Amaryan, University of Bochum, December 6, 2011
G-Parity Violating Decay of φ Meson ?
M=1.021 GeVσ = 0.005 GeV
PDG Exp. limit Br<1.8x10-5
η‘
Φ
f1(1285)
Theory prediction:Br( ) ~3x10-7 Achasov, I.J.M.Phys. A, Vol.7, No. 20(1992, 4825)
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M.Amaryan, University of Bochum, December 6, 2011
~340K η’ events and ~1M on tape
~40K events
arXiv:1012.1117v2 [hep-ex]
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M.Amaryan, University of Bochum, December 6, 2011
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M.Amaryan, University of Bochum, December 6, 2011
not corrected for acceptance
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M.Amaryan, University of Bochum, December 6, 2011
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M.Amaryan, University of Bochum, December 6, 2011
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M.Amaryan, University of Bochum, December 6, 2011
From g11 run only
Adding g12 will reduce stat.err. by factor of two
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M.Amaryan, University of Bochum, December 6, 2011
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M.Amaryan, University of Bochum, December 6, 2011
Radiative Decay
ρ/
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M.Amaryan, University of Bochum, December 6, 2011
Theory:F.Stollenwerk et al.,arXiv:1108.2419v1[nucl-th]
WASA-at-COSY[17]
BNL-AGS[18]
CLAS
η->π+π-γ η’->π+π-γ
Eγ [GeV] Eγ [GeV]
Not corrected
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M.Amaryan, University of Bochum, December 6, 2011
Not corrected for acceptance
CLAS
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M.Amaryan, University of Bochum, December 6, 2011
Dalitz Decay of Pseudoscalar Mesons
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M.Amaryan, University of Bochum, December 6, 2011
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M.Amaryan, University of Bochum, December 6, 2011
Summary
-High statistics experimental results on rare and dominant decay modes of pseudoscalar and vector mesons are obtained with CLAS at JLAB.- In some channels CLAS data are exceeding the world statistics -Dalitz decay of etaprime is observed for the first time-Combining data from different world facilities will help to provide high quality and high statistics data-We believe that common efforts of European and US groups related to meson decays will be extremely useful -Thanks for the opportunity to give a seminar in University of Bochum !