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S. Stepanyan Town Meeting, Rutgers Univ., January 12-14 2007 Meson spectroscopy with CLAS CLAS12 Experiments with coherent production require: detection of A ’ at t’t min (E k >few MeV) - thin targets (~10 -3 g/cm 2 ) small size, high flux (virtual) photon beams Coherent production on nuclei can be used to eliminate s-channel background Successful PWA of CLAS photoproduction data showed a feasibility of meson spectroscopy studies using the CLAS detector It also reviled importance of backgrounds from ’s and N*’s CLAS(12) with BoNuS RTPC and with available high precision, high intensity electron beams opens a new avenue for meson spectroscopy using coherent production on nuclei a2a2 CLAS/g6: p ’ n + + - Background from s-channel processes complicates PWA (need a high statistics data), introduces ambiguities
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S. Stepanyan Town Meeting, Rutgers Univ., January 12-14 2007 Coherent production of 0 and 0 ’ on 4 He (PR-07-009) Only C =-1 -exchanges is allowed, Natural Parity Exchange (NPE) The helicity of the produced state will be that of the incoming photon, = , production of 0 ( 0 ’) in S-wave is forbidden Final states 0 and 0 ’ have I =1, C =+1, G =-1, and P =(-1) l. Resonance in the P- wave will be an exotic - I G J PC = 1 - 1 -+ Coherent production on 4 He eliminates s-channel contribution Scattering off of the spin and isospin zero target works as a spin and parity filter for final state mesons
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S. Stepanyan Town Meeting, Rutgers Univ., January 12-14 2007 CLAS12 with thin targets ( 3 H, 3 He, 4 He) and with small angle tagger Spectroscopy can be extended to the higher masses (~3 GeV) and to the charged modes Electroproduction at very small Q 2 ’ 10 -3, scattering angles 1 o -2 o, is equivalent to photoproduction with partially linearly polarized photons, complimentary solution to photon bremsstrahlung beams
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