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CB TAPS October 2004

CB TAPS October 2004. h ´ Photoproduction off the Nucleon. Martin Kotulla. Perspectives: h ‘. excitation region close to w=2 GeV: density of resonances increases very few channels studied ( p )

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CB TAPS October 2004

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  1. CB TAPS October 2004 h´ Photoproduction off the Nucleon • Martin Kotulla

  2. Perspectives: h‘ • excitation region close to w=2 GeV: • density of resonances increases • very few channels studied (p) • h‘ is a promising channel (only a few partial waves contribute at threshold), isospin filter • excitation region close to 2 GeV: • P13 (1900) [*], F17 (1990) [**], F15 (2000) [**], D13 (2080) [**], S11 (2090) [*], P11 (2100) [*] • biggest h‘coupling: S. Capstick and W. Roberts, PRD 49 (1994) 4570D13 (2080) [**] and S11 (2090) [*] Meson 2004 Martin Kotulla, University Basel

  3. Status: h‘ • Published data: • total cross sections from old bubble chamber experiments • SAPHIR: two data sets including angular distributions, • Interpretation: • R. Plötzke et al., PLB 444 (1998) 555 S11(1900) and P11 (1990) • J. Barth et al., NPA 691 (2001) 374 Regge exchange S11 close to threshold • Chiang et al., PRC 68 (2003) 045202 S11 (P1X ) and Regge exchange • Z. Li J.Phys. G 23 (1997) 1127, Sibirtsev et al., nucl-th/0303044 t-channel exchange (r, w) subtreshold S11(1535) and many contradicting interpretations Meson 2004 Martin Kotulla, University Basel

  4. h‘ Models • Ploetzke et al., PLB444 (1998) 555 • J.Link et al. PHD thesis (unpublished) Sibirtsev, Elster, Krewald, Speth nucl-th/0303044 (2003) • eff. Langragian model • r,w t-channel exchange (dashed) • t-channel + S11(1535) Meson 2004 Martin Kotulla, University Basel

  5. Identification g p h‘p : • threshold (1447MeV) up to 2530 MeV • h‘identification:h‘2p0 h 6g (8.2%)h‘2p0 h 10g (6.8%) • missing mass cross section: • cross sections determined by fit of the invariant mass individualy in each bin of the angular distributions preliminary results: • ca 50% of full data set • calibrations not final • kinematic fit to increase resolution Meson 2004 Martin Kotulla, University Basel

  6. h‘ Models • Ploetzke et al., PLB444 (1998) 555 • Chiang et al., PRC 68 (2003) 045202 • reggeized model • S11(1950) necessary for interference • additional P1X(1950) possible dashed: reggeized t-channel dotted: S11(1950) only solid: regge and S11(1950) dashed dotted: r,w t-channel Meson 2004 Martin Kotulla, University Basel

  7. h‘ Models • Chiang et al., PRC 68 (2003) 045202 • polarization observables • sensitivity to resonances at Eg=1.59GeV solid: regge and S11(1950) dashed: regge and S11(1950) and P11(1950) dotted: regge and S11(1950) and P13(1950) • S might be changed if additonal D wave contributes (like in the case of h) • longitudinally pol. target: G very sensitive to P1X resonances (but pol.) „GDH“ E Meson 2004 Martin Kotulla, University Basel

  8. h‘ on deuterium g p h‘p : • threshold 1447MeV • with 1500MeV electron beam energy:additional tagger for high photon beam energies necessary J.Weiss et al., EPJ A 11, 371 (2001) A. Sibirtsev et al., PRC 65, 044007 (2002) g d h‘X : • threshold at 1202 MeV • neutron data has been measured at ELSA with CBTAPS (rough cross section on neutron) • study of h‘ FSI (h‘ N interaction) Meson 2004 Martin Kotulla, University Basel

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