Photoproduction and Decays of Pseudoscalar Mesons in CLAS Moskov Amaryan Old Dominion University Norfolk, Virginia, USA M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 Outline CLAS setup at JLAB -Classification of Mesons -Hadronic decays -Radiative decays -Dalitz decays -Summary M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 JLab Site: The 6 GeV CW Electron Accelerator 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 M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 The CLAS Photon Tagger M.Amaryan, University of Bochum, December 6, 2011

CEBAF Large Acceptance Spectrometer Torus magnet 6 superconducting coils Large angle calorimeters Lead/scintillator, 512 PMTs Liquid D2 (H2)target + g start counter; e minitorus Gas Cherenkov counters e/p separation, 216 PMTs Drift chambers argon/CO2 gas, 35,000 cells Electromagnetic calorimeters Lead/scintillator, 1296 PMTs Time-of-flight counters plastic scintillators, 684 PMTs M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 Horizontal cut through the CLAS detector M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 (Reminder) M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 Meson Families Type S L P J JP Pseudscalar mesons - 0- Axial vector mesons 1 + 1+ Vector mesons 1- Scalar mesons 0+ Tensor mesons 2 2+ J=L+S P=(-1)L+1 C=(-1)L+S G=(-1)L+S+I M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 In the SU(3) Group Theory Language M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 OUTLINE - Photoproduction of Pseudoscalar Mesons with CLAS Hadronic Decays Radiative Decays Also Vector Mesons: M.Amaryan, University of Bochum, December 6, 2011

Missing Mass Distribution gp pX Single charged track events identified as a proton M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 Missing Mass π0 η 3 charged track events identified as a proton, π+ and π- M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 Okubo-Zweig-Iizuka Rule OZI allowed OZI suppressed M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 ω-ϕ Interference in e+e- annihilation M.N.Achasov hep-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? M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 OZI Rule Violating Decay of ϕ meson in photoproduction γ+p = pπ+π-π0 ω η‘ ϕ Hadronic decay η‘ ϕ η (~2M events) M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 G-Parity Violating Decay of φ Meson ? η‘ f1(1285) PDG Exp. limit Br<1.8x10-5 Φ M=1.021 GeV σ = 0.005 GeV Theory prediction: Br( ) ~3x10-7 Achasov, I.J.M.Phys. A, Vol.7, No. 20(1992, 4825) M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 ~340K η’ events and ~1M on tape arXiv:1012.1117v2 [hep-ex] ~40K events M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 not corrected for acceptance M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 From g11 run only Adding g12 will reduce stat.err. by factor of two M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 Radiative Decay ρ/ M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 WASA-at-COSY[17] BNL-AGS[18] Theory: F.Stollenwerk et al., arXiv:1108.2419v1 [nucl-th] η->π+π-γ η’->π+π-γ CLAS  Not corrected Eγ [GeV] Eγ [GeV] M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 CLAS Not corrected for acceptance M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011 Dalitz Decay of Pseudoscalar Mesons M.Amaryan, University of Bochum, December 6, 2011

M.Amaryan, University of Bochum, December 6, 2011

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 ! M.Amaryan, University of Bochum, December 6, 2011