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SUMMARY:S11 resonances in pion scattering and pion photoproduction
DTSTART;VALUE=DATE-TIME:20040709T130000Z
DTEND;VALUE=DATE-TIME:20040709T140000Z
DTSTAMP;VALUE=DATE-TIME:20261113T102216Z
UID:indico-event-1368@indico.ific.uv.es
DESCRIPTION:A self-consistent analysis of pion scattering and pion photopr
 oduction within a coupled channels dynamical model is presented. The resul
 ts indicate the existence of a third and a fourth $S_{11}$ resonance with 
 the masses $1846\\pm 47$ and $2113\\pm 70$ MeV. In the case of pion photop
 roduction\, we obtain background contributions to the imaginary part of th
 e $S$-wave multipole which differ considerably from the result based on th
 e K-matrix approximation. Within the dynamical model these background cont
 ributions become large and negative in the region of the $S_{11}(1535)$ re
 sonance. Due to this fact much larger resonance contributions are required
  in order to explain the results of the recent multipole analysis. For the
  first $S_{11}(1535)$ resonance we obtain as a value of the electromagneti
 c helicity amplitude: $A_{1/2}=72\\pm 2 \\times 10^{-3}$GeV$^{-1/2}$.}\n\n
 https://indico.ific.uv.es/event/1368/
LOCATION:Edf. Institutos de Investigación Sala Seminarios IFIC
URL:https://indico.ific.uv.es/event/1368/
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