Excited-State Effects in Nucleon Sigma Terms from a Variational Analysis
Abstract
We investigate excited-state effects in nucleon sigma-terms in lattice QCD using twisted-mass clover-improved fermion ensembles. We study correlation functions with nucleon and multihadron nucleon-σ-meson interpolating operators. The analysis is performed using three gauge ensembles, including one ensemble simulated with two degenerate light, a strange, and a charm quark with quark masses tuned to approximately their physical value. We solve the generalized eigenvalue problem that arises from the matrix of correlators and show that the three-point function for the light sigma-term obtained using the optimal linear combination of interpolating operators has substantially reduced time dependence without loss of statistical precision. We apply Laplace filtering and investigate residual excited-state contributions in the extraction of σπN. Using the same optimal linear combination of correlators as for σπN for the strange sigma-term we also observe suppressed excited state contributions over an extended range of source--sink time separations. For the charm sigma-term, we observe negligible time dependence within the large statistical uncertainties, and these improvements show no significant effect.
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BibTeX
@misc{alexandrou2026excitedstate,
title = {{Excited-State Effects in Nucleon Sigma Terms from a Variational Analysis}},
author = {Constantia Alexandrou and Giannis Koutsou and Yan Li and Srijit Paul and Ferenc Pittler},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.20362},
eprint = {2610.20362},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.20362},
}
RIS
TY - UNPB
TI - Excited-State Effects in Nucleon Sigma Terms from a Variational Analysis
AU - Constantia Alexandrou
AU - Giannis Koutsou
AU - Yan Li
AU - Srijit Paul
AU - Ferenc Pittler
PY - 2026
DA - 2026/10/14
PB - arXiv
DO - 10.48550/arxiv.2610.20362
UR - https://arxiv.org/abs/2610.20362
AB - We investigate excited-state effects in nucleon sigma-terms in lattice QCD using twisted-mass clover-improved fermion ensembles. We study correlation functions with nucleon and multihadron nucleon-σ-meson interpolating operators. The analysis is performed using three gauge ensembles, including one ensemble simulated with two degenerate light, a strange, and a charm quark with quark masses tuned to approximately their physical value. We solve the generalized eigenvalue problem that arises from the matrix of correlators and show that the three-point function for the light sigma-term obtained using the optimal linear combination of interpolating operators has substantially reduced time dependence without loss of statistical precision. We apply Laplace filtering and investigate residual excited-state contributions in the extraction of σ_πN. Using the same optimal linear combination of correlators as for σ_πN for the strange sigma-term we also observe suppressed excited state contributions over an extended range of source--sink time separations. For the charm sigma-term, we observe negligible time dependence within the large statistical uncertainties, and these improvements show no significant effect.
ER -