Related papers: Investigating $\mathbf{N \to N\pi}$ axial matrix e…
Transition helicity amplitudes $\gamma_{v}NN^*$ (electrocouplings) were determined for prominent excited proton states with masses below 1.8 GeV in independent analyses of major meson electroproduction channels: $\pi^{+}n$, $\pi^0p$ and…
Data from the first physics run at the Relativistic Heavy-Ion Collider at Brookhaven National Laboratory from the STAR experiment have been analyzed using three-pion correlations to study whether pions are emitted independently at…
We present a nucleon resonance analysis by simultaneously considering all pion- and photon-induced experimental data on the final states gamma N, pi N, 2 pi N, eta N, K Lambda, K Sigma, and omega N for energies from the nucleon mass up to…
We present preliminary results on the axial form factor $G_A(Q^2)$ and the induced pseudoscalar form factor $G_P(Q^2)$ of the nucleon. A systematic analysis of the excited-state contributions to form factors is performed on the CLS ensemble…
Resonances and final state interactions (FSI) play a role in the formation of CP violation (CPV) constrained by CPT invariance. We provide a general formulation of CPV including resonances and FSI starting from the CPT constraint. Our…
We employ chiral perturbation theory to calculate the nucleon-pion-state contribution to the 3-point correlation functions measured in lattice QCD to compute various moments of parton distribution functions (quark momentum fraction,…
We evaluate the $\pi N$ coupling constant using a QCD sum rule based on the pion-to-vacuum matrix element of the correlator of two interpolating nucleon fields. The part of the correlator with Dirac structure $k\llap/\gamma_5$ is used,…
We present an updated analysis of the quark mass dependence of the nucleon mass and nucleon axial-vector coupling g_A, comparing different formulations of SU(2) Baryon Chiral Effective Field Theory, with and without explicit delta (1232)…
Spin-resolved and temperature-dependent appearance-potential spectra of ferromagnetic Nickel are measured and analyzed theoretically. The Lander self-convolution model which relates the line shape to the unoccupied part of the local density…
We calculate the nucleon form factors G_A and G_P of the isovector axial-vector current and the pion-nucleon form factor G_piN in manifestly Lorentz-invariant baryon chiral perturbation theory up to and including order O(p^4). In addition…
We calculate in chiral perturbation theory the parity-violating two-pion exchange nucleon-nucleon potentials at leading one-loop order. At a distance of $r= m_\pi^{-1} \simeq 1.4 $fm they amount to about $\pm 16%$ of the parity-violating…
The Feynman-Hellmann theorem can be derived from the long Euclidean-time limit of correlation functions determined with functional derivatives of the partition function. Using this insight, we fully develop an improved method for computing…
Effective three meson couplings, based in flavor U(3) quark-antiquark interactions, are considered to describe two light neutral axial meson Strong decays, $A \sim f_1(1285)$ and $f_{1S} (1420)$, and the charged rho meson decay in the…
The extension of the concept of generalized parton distributions leads to the introduction of baryon to meson transition distribution amplitudes (TDAs), non-diagonal matrix elements of the nonlocal three quark operator between a nucleon and…
We have calculated coupling constants of a neutral pion with the lowest two nucleon resonances. This includes both the diagonal as well as non-diagonal coupling constants involving a nucleon resonance and a nucleon. For this, we first…
We report on our calculation of the nucleon axial charge gA in QCD with two flavours of dynamical quarks. A detailed investigation of systematic errors is performed, with a particular focus on contributions from excited states to…
We compute the polarisability of the nucleon to leading order in chiral perturbation theory. The contributions from kaons and baryon resonances as intermediate states are included in addition to the contribution from pions and nucleons that…
Quantum fluctuations in QCD influence nucleon structure and interactions, with pion production serving as a key probe of chiral dynamics. In this study, we present a lattice QCD calculation of multipole amplitudes at threshold, related to…
Data from the first physics run at the Relativistic Heavy-Ion Collider at Brookhaven National Laboratory, Au+Au collisions at $\sqrt{s_{NN}}=130$ GeV, have been analyzed by the STAR Collaboration using three-pion correlations with charged…
Electroproduction of pions on the nucleon near the threshold is analyzed within the framework of baryon chiral perturbation theory. We give a thorough discussion of the low--energy theorems related to charged and neutral…