D and D_s in mass loaded flux tube
  Heavy-light hadrons are studied in a mass loaded flux tube model. The study indicates that the dynamics of mesons and baryons containing a $c$ quark is well described by the mass loaded flux tube. The hypothesis of good diquark-antiquark degeneracy is found reasonable in heavy-light quark systems. The spectrum of charmed ($D$) and charmed strange ($D_s$) mesons is systematically computed. $D$ and $D_s$ in 1D multiplets are predicted to have lower masses in comparison with other theoretical predictions. The predicted masses of the $1^-(1^3D_1)$ and the $3^-(1^3D_3)$ $D_s$ agree well with those of recently observed $D_{s1}(2700)^{\pm}$ and $D_{sJ}(2860)$, respectively. 
Hong-Yun Shan and Ailin Zhang