Speaker
Description
Nucleon sigma terms are important for the decomposition of the nucleon mass and for searches for new physics beyond the Standard Model involving scalar interactions. A persistent tension between lattice QCD and phenomenological determinations may be due to uncontrolled excited-state contamination in lattice QCD analyses. In previous work at $m_\pi=429$ MeV, we showed that this contamination is dominated by $N\sigma$ states and can be strongly suppressed with a $2\times 2$ variational analysis using $N$ and $N\sigma$ operators. In this talk, we present preliminary results at $m_\pi=222$ MeV, where the $\sigma$ becomes unstable and decays into $\pi\pi$. We investigate whether the same small variational basis can remove the expected $N\pi\pi$ contamination through the overlap of the $N\sigma$ operator with these states.