Vacuum phenomenology of the chiral partner of the nucleon in a linear sigma model with vector mesons

Understand

We investigate a linear sigma model with global chiral $U(2)_{R} \times U(2)_{L}$ symmetry.

• The mesonic degrees of freedom are the standard scalar and pseudoscalar mesons and the vector and axial-vector mesons.
• The baryonic degrees of freedom are the nucleon, $N$, and its chiral partner, $N^{*}$, which is usually identified with N(1535).
• The chiral partner is incorporated in the so-called mirror assignment, where the nucleon mass is not solely generated by the chiral condensate but also by a chirally invariant mass term, $m_{0}$.