Related papers: The $\pi \sigma$-Axial Exchange Current
Relativistic exchange current corrections to the impulse approximation in low and intermediate energy neutrino--nucleus scattering are presented assuming non--vanishing strange quark form factors for constituent nucleons. Two--body exchange…
The exchange charge density operators that correspond to the Fermi-invariant decomposition of quark-quark interactions have been constructed. Their effect on the electromagnetic charge radii of the nucleons, in combination with that of the…
The structure of the weak axial pion exchange current is discussed in various models. It is shown how the interplay of the chiral invariance and the double counting problem restricts uniquely the form of the pion potential term, in the case…
We evaluate the "$\sigma$" exchange contribution to the $\bar{K}N\to\bar{K}N$ scattering within a chiral unitary approach. We show that the chiral transition potentials for $\pi \pi \to K \bar{K}$ in the $t$-channel lead to a "$\sigma$"…
The charge-dependent nucleon-nucleon ($NN$) interactions are crucial in understanding the nuclear structure and reaction problems. This work explores the charge-dependent $NN$ interaction in covariant chiral effective field theory. By…
We evaluate the two pion exchange contribution to the nucleon-nucleon potential in configuration space using a "minimal chiral model" containing only pions and nucleons. We argue that this model has nowadays a rather firm conceptual basis,…
In this letter we study the high energy behavior of the forward differential cross section for the $^{18}O(\pi^+,\pi^-)^{18}Ne$ double charge exchange reaction. We have evaluated the sequential and the meson exchange current mechanisms. The…
I discuss how the axial current coupling constant $g_A$ renormalized in scale symmetric chiral EFT defined at a chiral matching scale impacts on the axial current matrix elements on beta decays in nuclei with and without neutrinos. The…
The meson(K and $\pi$) exchange currents for the hypernuclear magnetic moments are calculated using the effective Lagrangian method. The seagull diagram, the mesonic diagram and the $\Sigma^0$-excitation diagram are considered. The…
We study the leading isospin-breaking contributions to the two-nucleon two-pion exchange potential due to explicit Delta degrees of freedom in chiral effective field theory. In particular, we find important contributions due to the delta…
We present theoretical results for $(\gamma, \pi^0 \pi^0)$ production on nucleons and nuclei in the kinematical region where the scalar isoscalar $\pi \pi$ amplitude is influenced by the $\sigma$ pole. The final state interaction of the…
We derive the leading contribution to the four-nucleon force within the framework of chiral effective field theory. It is governed by the exchange of pions and the lowest-order nucleon-nucleon contact interaction and includes effects due to…
We study the nucleon-nucleon interaction in the isoscalar-scalar channel using t he chiral unitary approach. The $t$-matrix of the pion-pion scattering in this c hannel is summed up to all orders using the B-S equation. We find that the…
The contribution of axial anomaly to charge symmetry breaking in pion-nucleon coupling constants is calculated within instanton model for QCD vacuum. It has been demonstrated that the contribution is large and allows to explain…
We calculate the contribution to the nuclear energy density functional which arises from iterated pion-photon exchange between nucleons. In heavy nuclei, this novel charge symmetry breaking interaction leads to an additional binding of each…
We derive the leading two-pion exchange contributions to the two-nucleon electromagnetic current operator in the framework of chiral effective field theory using the method of unitary transformation. Explicit results for the current and…
We evaluate, within one-loop chiral perturbation theory, the two-pion exchange diagrams with single and double delta-isobar excitation contributing to elastic NN-scattering. We find that virtual $\Delta$-excitation processes (in the static…
We show the necessity of two-nucleon axial currents and associated pion emission/ absorption operators for the partial conservation of the axial current (PCAC) nuclear matrix elements with arbitrary nuclear dynamics described by a…
We describe a model for pion production off nucleons and coherent pions from nuclei induced by neutrinos in the 1 GeV energy regime. Besides the dominant Delta pole contribution, it takes into account the effect of background terms required…
Sum of the time component of $\Sigma$ term and the induced pseudo scalar term in axial current is shown to be the t-channel pion pole in Born terms for pion electroproduction near threshold. We also show that this $\Sigma$ term represents…