v 2 9 N ov 1 99 8 On the D ∗ + s → D + s π 0 decay in the Effective quark model with chiral U ( 3 ) × U ( 3 ) symmetry

The partial width of the decay D s → D s π going through the violation of isotopical symmetry is computed with respect to the partial width of the radiative decay D s → D s γ in the effective quark model with chiral U(3)× U(3) symmetry incorporating Heavy quark effective theory (HQET) and Chiral perturbation theory at the quark level (CHPT)q. We investigate a sensitivity of the ratio R0 = Γ(D ∗+ s → D s π )/Γ(D s → D s γ) to current s–quark mass corrections and find a strong dependence. PACS number(s): 13.30.Ce, 12.39.Ki, 14.20.Lq, 14.20.Mr E–mail: [email protected], Institut für Kernphysik, Technische Universität Wien, Wiedner Hauptsr. 8–10, A–1040 Vienna, Austria Permanent Address: State Technical University, Department of Nuclear Physics, 195251 St. Petersburg, Russian Federation