Wed·Sep 9, 2026Wednesday·September 9, 2026

Nucleon-sigma terms at $m_{\pi }=222\mathrm{MeV}$ with a variational analysis from lattice QCD

Lorenzo Barca🇩🇪 · Gunnar Bali🇩🇪 · Sara Collins🇩🇪 · Marcel Rodekamp🇩🇪

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 $m_{\pi }=429\mathrm{MeV}$, we showed that this contamination is dominated by $N\sigma$ states and can be strongly suppressed with a variational analysis using $N$ and $N\sigma$ operators. In this talk, we present preliminary results at $m_{\pi }=222\mathrm{MeV}$, 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.