Chiral transitions in heavy-light mesons

The mass shifts of the P-wave Ds and Bs mesons due to coupling to DK, D*K and BK, B*K channels are studied using the chiral quark-pion Lagrangian not containing fitting parameters. The large mass shifts down ∼140 MeV and ∼100 MeV for Ds*(0+) and Ds(1+') and ∼100 MeV for Bs*(0+) and Bs(1+') are calculated. Two factors are essential for large mass shifts: strong coupling of the 0+ and 1+' states to the S-wave decay channel, containing a Nambu-Goldstone meson, and the chiral flip transitions due to the bispinor structure of both heavy-light mesons. The masses M(Bs*(0+))=5710(15) MeV and M(Bs(1+'))=5730(15) MeV, very close to M(B(0+)) and M(B(1+')), are predicted. The experimental limit on the width Γ(Ds1(2536))<2.3 MeV puts strong restrictions on the admissible mixing angle between the 1+ and 1+' states, |φ|<6 deg., which corresponds to the mixing angle θ between the 3P1 and 1P1 states, 29 deg. <θ<41 deg.