Determination of $f_0-\sigma$ mixing angle through $B_s^0 \to   J/\Psi~f_0(980)(\sigma)$ decays
  We study $B_s^0 \to J/\psi f_0(980)$ decays, the quark content of $f_0(980)$ and the mixing angle of $f_0(980)$ and $\sigma(600)$. We calculate not only the factorizable contribution in QCD facorization scheme but also the nonfactorizable hard spectator corrections in QCDF and pQCD approach. We get consistent result with the experimental data of $B_s^0 \to J/\psi f_0(980)$ and predict the branching ratio of $B_s^0 \to J/\psi \sigma$. We suggest two ways to determine $f_0-\sigma$ mixing angle $\theta$. Using the experimental measured branching ratio of $B_s^0 \to J/\psi f_0(980) $, we can get the $f_0-\sigma$ mixing angle $\theta$ with some theoretical uncertainties. We suggest another way to determine $f_0-\sigma$ mixing angle $\theta$ using both of experimental measured decay branching ratios $B_s^0 \to J/\psi f_0(980) (\sigma)$ to avoid theoretical uncertainties. 
Jing-Wu Li, Dong-Sheng Du, Cai-Dian L\"u
hep-ph