Sigma Meson Cloud and Proton's Light Flavor Sea Quarks
  We take into account the sigma meson cloud effect in the meson cloud model to calculate the distributions of light flavor sea quarks in the proton. Our calculation gives a better description of the data for $\bar{d}(x)/\bar{u}(x)$. We also provide a picture that the probability of finding a physical proton in a Fock state $|N\omega> $ is reasonable small with a smaller cutoff $\Lambda_{\omega}$. 
Feng Huang, Rong-Guang Xu, Bo-Qiang Ma