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The nucleon-nucleon interaction arising from the exchange of three pions and the excitation of $\Delta(1232)$-isobars in intermediate states is studied. Approximating the $\Delta$-propagator by the inverse $\Delta$N mass-splitting,…

Nuclear Theory · Physics 2015-09-02 N. Kaiser

The interaction mediated by irreducible pion and gluon exchange between constituent quarks is calculated and shown to have a strong tensor component, which tends to cancel the pion exchange tensor interaction between quarks. Its spin-spin…

High Energy Physics - Phenomenology · Physics 2009-10-31 C. Helminen , D. O. Riska

Exchange interactions between isolated pairs of spin centers in diamond have been calculated, based on an accurate atomistic electronic structure for diamond and any impurity atoms, for spin-center separations up to 2~nm. The exchange…

Mesoscale and Nanoscale Physics · Physics 2016-06-29 V. R. Kortan , C. Şahin , M. E. Flatté

A microscopic model for the $N\bar N\to\pi\pi$ process is presented in the meson exchange framework, which in the pseudophysical region agrees with available quasiempirical information. The scalar ($\sigma$) and vector ($\rho$) piece of…

Nuclear Theory · Physics 2009-09-25 C. Schütz , J. W. Durso , K. Holinde , B. C. Pearce , J. Speth

We investigate isospin breaking in low-energy pion-nucleon scattering in the framework of chiral perturbation theory. This work extends the systematic analysis of [1] to the energy range above threshold. Various relations, which identically…

High Energy Physics - Phenomenology · Physics 2009-10-31 Nadia Fettes , Ulf-G. Meißner

An exploratory study of chiral four-nucleon interactions in nuclear and neutron matter is performed. The leading-order terms arising from pion-exchange in combination with the chiral $4\pi$-vertex and the chiral NN$3\pi$-vertex are found to…

Nuclear Theory · Physics 2015-06-11 N. Kaiser

We calculate isospin breaking in pion-nucleon scattering in the threshold region in the framework of covariant baryon chiral perturbation theory. All effects due to quark mass differences as well as real and virtual photons are consistently…

High Energy Physics - Phenomenology · Physics 2011-11-22 Martin Hoferichter , Bastian Kubis , Ulf-G. Meißner

Nuclear potentials are known to exhibit a considerable degree of scheme dependence. For one- and two-pion exchange nucleon-nucleon (NN) potentials, unitary ambiguities start showing up at the level of the leading relativistic corrections to…

Nuclear Theory · Physics 2025-05-06 Victor Springer , Hermann Krebs , Evgeny Epelbaum

Pion exchange is the central ingredient to nucleon-nucleon interactions used in nuclear structure calculations, and one pion exchange (OPE) enters at leading order in chiral effective field theory. In the $^{2S+1}L_J={^1S_0}$ partial wave,…

Nuclear Theory · Physics 2022-08-29 Chinmay Mishra , A. Ekström , G. Hagen , T. Papenbrock , L. Platter

The parity-violating nucleon-nucleon (NN) potential is considered up to next-to-next-to leading order in heavy-baryon chiral perturbation theory. We include one-pion exchange at leading order and the two-pion exchange and two-nucleon…

Nuclear Theory · Physics 2008-11-26 C. H. Hyun , S. Ando , B. Desplanques

We investigate the parity-violating nucleon-nucleon potential as obtained in chiral effective field theory. By using resonance saturation we compare the chiral potential to the more traditional one-meson exchange potential. In particular,…

Nuclear Theory · Physics 2014-07-17 J. de Vries , N. Li , Ulf-G. Meißner , N. Kaiser , X. -H. Liu , S. -L. Zhu

We study the three-nucleon force in chiral effective field theory with explicit Delta-resonance degrees of freedom. We show that up to next-to-next-to-leading order, the only contribution to the isospin symmetric three-nucleon force…

Nuclear Theory · Physics 2008-11-26 E. Epelbaum , H. Krebs , Ulf-G. Meißner

We discuss the electromagnetic corrections to the pion-nucleon scattering lengths generated by minimal e. m. coupling from a knowledge of the low energy expansion of the pion-nucleon elastic scattering amplitude as well as from the nucleon…

High Energy Physics - Phenomenology · Physics 2007-05-23 T. E. O. Ericson

We derive from the subleading contributions to the chiral three-nucleon force (short-range terms and relativistic corrections, published in Phys. Rev. C84, 054001 (2011)) a density-dependent two-nucleon interaction $V_\text{med}$ in…

Nuclear Theory · Physics 2018-12-05 N. Kaiser , V. Niessner

Spin-isospin response in exotic nuclear systems is investigated. It is found that in some nuclei excitations with pionic quantum numbers (0-, 1+, 2-, ...) appear at very low energies with large transition probabilities, which is an…

Nuclear Theory · Physics 2015-10-28 Elena Litvinova

We discuss ${\gamma}{\gamma}\to {\pi}{\pi}$ reactions, starting from the two-pion threshold up to about $\sqrt{s_{{\gamma}{\gamma}}}$ = 6 GeV. We include the dipion continuum due to pion exchange (for ${\pi}^+{\pi}^-$) and ${\rho}^\pm$…

Nuclear Theory · Physics 2013-05-29 Mariola Kłusek-Gawenda , Antoni Szczurek

We calculate the equation of state of isospin-symmetric nuclear matter in the three-loop approximation of chiral perturbation theory. The contributions to the energy per particle $\bar E(k_f)$ from one- and two-pion exchange diagrams are…

Nuclear Theory · Physics 2009-11-07 N. Kaiser , S. Fritsch , W. Weise

Recent analyses of low-energy pion-nucleon experimental data have provided clear evidence for the violation of the isospin symmetry of the strong interaction. In the present work, it is shown that the single-charge-exchange reaction is the…

High Energy Physics - Phenomenology · Physics 2007-05-23 E. Matsinos

We calculate the imaginary parts of the isoscalar scalar and isovector electromagnetic form factors of the nucleon up to two-loop order in chiral perturbation theory. Particular attention is paid on the correct behavior of Im $\sigma_N(t)$…

Nuclear Theory · Physics 2009-11-10 N. Kaiser