A calculation of the sigma meson mass in nuclear matter

We calculate the mass and width of the crσ-meson in nuclear medium by considering that it couples to two virtual pions and to a pair of nucleonantinucleon states and to particle-hole states. The mass is calculated by using the spectral function in the Walecka model, finding that it is about 520 MeV. In addition, we have obtained the value of 700 MeV for the width of its spectral function, showing that it has increased respect to that in vacuum. We find that there is a reduction in the mass value compared with that in vacuum. This result is consistent with those reported by other authors who have used different models predicting a decreasing of the mass as a function of the density.