M. F. M. Lutz, (GSI, Darmstadt (Germany))

 Title: "Radiative and isospin-violating decays of
 D_s-mesons in the hadrogenesis conjecture"


 Abstract

 The masses and decays of the scalar D_{s0}^*(2317) and axial-vector
 D_{s1}^*(2460) charmed strange mesons are calculated consistently in the 
 hadrogenesis conjecture. These mesons decay either strongly into the 
 isospin-violating \pi^0 D_s and \pi^0 D_s^* channels or electromagnetically.
 They are generated by coupled-channel dynamics based on the leading 
 order chiral Lagrangian. The effect of chiral corrections to chiral order 
 Q_\chi^2 is investigated. We show that taking into account large-N_c 
 relations to determine the strength of these correction terms implies a
 measurable signal for an exotic axial-vector state in the \eta \,D^* 
 invariant mass distribution. The one-loop contribution to the 
 electromagnetic decay amplitudes of scalar and axial-vector states is 
 calculated. The Lagrangian describing electromagnetic interactions is
 obtained by gauging the chiral Lagrangian for hadronic interactions and 
 adding gauge-invariant correction terms to chiral order Q_\chi^2. In 
 addition the role of light vector meson degrees of freedom is explored. 
 We confront our results with measured branching ratios. Once the light 
 vector mesons are included, a natural explanation of all radiative decay 
 parameters is achieved.