Related papers: The pion-nucleon sigma term from lattice QCD
Nucleon sigma terms are quantities that play an important role in various areas: among others, they connect the pion-nucleon and the kaon-nucleon amplitudes to the hadron spectrum and they are also relevant for the direct detection of Dark…
We present lattice QCD calculations of nucleon electromagnetic form factors using pion masses $m_\pi$ = 149, 202, and 254 MeV and an action with clover-improved Wilson quarks coupled to smeared gauge fields, as used by the…
We report a new analysis of lattice simulation results for octet baryon masses in 2+1-flavor QCD, with an emphasis on a precise determination of the strangeness nucleon sigma term. A controlled chiral extrapolation of a recent PACS-CS…
The nucleon-pion-state contribution to QCD two- and three-point functions used in the calculation of the axial form factors of the nucleon are studied in chiral perturbation theory. For physically small quark masses the nucleon-pion states…
We present an extraction of the pion-nucleon ($\pi N$) scattering lengths from low-energy $\pi N$ scattering, by fitting a representation based on Roy-Steiner equations to the low-energy data base. We show that the resulting values confirm…
The nucleon-pion-state contributions to QCD two-point and three-point functions relevant for lattice calculations of the nucleon electromagnetic form factors are studied in chiral perturbation theory. To leading order the results depend on…
The long-range, parity-odd nucleon interaction generated by single pion exchange is captured in the parity-odd pion-nucleon coupling $h^1_\pi$. Its calculation in lattice QCD requires the evaluation of 4-quark operator nucleon 3-point…
We compute the axial, scalar, tensor and pseudoscalar isovector couplings of the nucleon as well as the induced tensor and pseudoscalar charges in lattice simulations with $N_f=2$ mass-degenerate non-perturbatively improved…
A non-zero signal $A_\gamma^\mathrm{np}=(-3.0\pm1.4\pm0.2)\times 10^{-8}$ of the gamma-ray asymmetry in the neutron-proton capture was recently reported by the NPDGamma Collaboration which provides the first determination of the $\Delta…
By using lattice QCD computations we determine the sigma terms and strangeness content of all octet baryons by means of an application of the Hellmann-Feynman theorem. In addition to polynomial and rational expressions for the quark mass…
We present a dedicated analysis of the influence of excited states on the calculation of nucleon matrix elements. This calculation is performed at a fixed value of the lattice spacing, volume and pion mass that are typical of contemporary…
We report the first Lattice QCD calculation using the almost physical pion mass mpi=149 MeV that agrees with experiment for four fundamental isovector observables characterizing the gross structure of the nucleon: the Dirac and Pauli radii,…
We present an updated analysis of meson-baryon sigma terms in the perturbative chiral quark model, which is based on effective chiral Lagrangian. The new feature concerns the inclusion of excited states in the quark propagator. Its…
We present a high statistics study of the pion and nucleon light and strange quark sigma terms using $N_f=2$ dynamical non-perturbatively improved clover fermions with a range of pion masses down to $m_\pi\sim 150$ MeV and several volumes,…
We present a QCD calculation of the $u$, $d$ and $s$ scalar quark contents of nucleons based on $47$ lattice ensembles with $N_f = 2+1$ dynamical sea quarks, $5$ lattice spacings down to $0.054\,\text{fm}$, lattice sizes up to…
The exponentially falling signal-to-noise ratio in all nucleon correlation functions, and the presence of towers of multihadron excited states with relatively small mass gaps makes extraction of matrix elements of various operators within…
In this work we present the analysis of the energy spectrum from a recent two-flavor ($N_f=2$) lattice QCD calculation for pion-pion scattering in the scalar, isoscalar channel (the $\sigma$-meson). The lattice simulation was performed for…
We present lattice results for the flavor diagonal charges of the proton from the analysis of eight ensembles generated using 2+1+1-flavors of highly improved staggered quarks (HISQ) by the MILC collaboration. The calculation includes all…
We investigate the possibility to determine the value of the pion-nucleon sigma term $\sigma_{\pi N}$ precisely by the experimental observables of the deeply bound pionic atoms. We discuss the sensitivity of the observables to $\sigma_{\pi…
We present updated results for the nucleon axial charge and electromagnetic (EM) form factors, which include a significant increase in statistics for all ensembles (up to 4000 measurements), as well as the addition of ensembles with pion…