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Nuclear electromagnetic currents derived in a chiral-effective-field-theory framework including explicit nucleons, $\Delta$ isobars, and pions up to N$^2$LO, {\it i.e.} ignoring loop corrections, are used in a study of neutron radiative…

Nuclear Theory · Physics 2014-11-18 S. Pastore , R. Schiavilla , J. L. Goity

The electric dipole polarizability quantifies the low-energy behaviour of the dipole strength and is related to critical observables such as the radii of the proton and neutron distributions. Its computation is challenging because most of…

Nuclear Theory · Physics 2016-09-28 M. Miorelli , S. Bacca , N. Barnea , G. Hagen , G. R. Jansen , G. Orlandini , T. Papenbrock

Previous calculations of the polarizabilities of the nucleon within the framework of heavy baryon chiral perturbation theory have included the contribution of the $\Delta$(1232) only its effect on various contact terms or have been…

High Energy Physics - Phenomenology · Physics 2008-11-26 Thomas R. Hemmert , Barry R. Holstein , Joachim Kambor

The electric dipole (E1) response of 208Pb has been precisely determined by measuring Coulomb excitation induced by proton scattering at very forward angles. The electric dipole polarizability, defined as inverse energy-weighted sum rule of…

Nuclear Experiment · Physics 2015-06-16 A. Tamii , P. von Neumann-Cosel , I. Poltoratska

We study the incoherent neutrinoproduction of photons and pions with neutrino energy E_{\nu} $\leqslant$ 0.5 GeV. These processes are relevant to the background analysis in neutrino-oscillation experiments, for example MiniBooNE [A. A.…

Nuclear Theory · Physics 2012-09-28 Xilin Zhang , Brian D. Serot

We study nuclear and neutron matter by combining chiral effective field theory with non-perturbative lattice methods. In our approach nucleons and pions are treated as point particles on a lattice. This allows us to probe larger volumes,…

Nuclear Theory · Physics 2009-11-10 Dean Lee , Bugra Borasoy , Thomas Schaefer

We report on a novel scheme based on the chiral Lagrangian. It is used to analyze pion-nucleon scattering, pion photoproduction, and nucleon Compton scattering. Subthreshold partial-wave amplitudes are calculated in chiral perturbation…

High Energy Physics - Phenomenology · Physics 2015-05-20 A. M. Gasparyan , M. F. M. Lutz

Chiral perturbation theory (ChPT) is the effective field theory of the strong interactions at low energies. We will address the issue of a consistent power counting scheme in a manifestly Lorentz-invariant formulation of baryon ChPT. As…

High Energy Physics - Phenomenology · Physics 2009-01-08 Stefan Scherer

We compute the $S$-factor of the proton-proton ($pp$) fusion reaction using chiral effective field theory ($\chi$EFT) up to next-to-next-to-leading order (NNLO) and perform a rigorous uncertainty analysis of the results. We quantify the…

Nuclear Theory · Physics 2016-07-27 B. Acharya , B. D. Carlsson , A. Ekström , C. Forssén , L. Platter

We present a theoretical parametrization of the nucleon electromagnetic form factors (FFs) based on a combination of chiral effective field theory and dispersion analysis. The isovector spectral functions on the two-pion cut are computed…

High Energy Physics - Phenomenology · Physics 2018-08-15 J. M. Alarcón , C. Weiss

We study radiative corrections to neutron beta decay and low-energy (anti)neutrino-nucleon scattering within a top-down effective field theory approach. As it was recently shown, a few electromagnetic and electroweak low-energy coupling…

High Energy Physics - Phenomenology · Physics 2023-05-02 Oleksandr Tomalak

We consider two-nucleon scattering close to threshold. Partial-wave amplitudes are obtained by an analytic extrapolation of subthreshold reaction amplitudes calculated in a relativistic formulation of chiral perturbation theory. The…

Nuclear Theory · Physics 2015-06-12 A. M. Gasparyan , M. F. M. Lutz , E. Epelbaum

In this thesis the polarized and unpolarized photon distributions of the nucleon (proton, neutron) $(\Delta)\gamma^N$, evaluated in the equivalent photon approximation (EPA), are computed theoretically and the possibility of their…

High Energy Physics - Phenomenology · Physics 2007-05-23 Cristian Pisano

Chiral effective field theory ($\chi$EFT) has proved to be a powerful microscopic framework for predicting the properties of neutron-rich nuclear matter with quantified theoretical uncertainties up to about twice the nuclear saturation…

High Energy Astrophysical Phenomena · Physics 2024-10-29 Duncan Neill , David Tsang , Christian Drischler , Jeremy W. Holt , William G. Newton

Chiral effective field theory (EFT) provides a systematic expansion for the coupling of WIMPs to nucleons at the momentum transfers relevant to direct cold dark matter detection. We derive the currents for spin-dependent WIMP scattering off…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 J. Menendez , D. Gazit , A. Schwenk

We calculate the nucleon-nucleon scattering amplitudes in the 1S0 and 3S1-3D1 channels at next-to-next to leading order starting from a recently proposed non-relativistic chiral effective theory, which includes dibaryon fields as…

Nuclear Theory · Physics 2010-04-06 Joan Soto , Jaume Tarrus

We employ the chiral nucleon-nucleon potential derived in ref.[1] to study bound and scattering states in the two-nucleon system. At next-to-leading order, this potential is the sum of renormalized one-pion and two-pion exchange and contact…

Nuclear Theory · Physics 2011-05-05 E. Epelbaum , W. Glöckle , Ulf-G. Meißner

We compute the Compton scattering off the nucleons in the framework of manifestly covariant baryon chiral perturbation theory (B$\chi$PT). The results for observables differ substantially from the corresponding calculations in heavy-baryon…

Nuclear Theory · Physics 2009-04-17 Vadim Lensky , Vladimir Pascalutsa

The strong interaction is not well understood at low energy, or for interactions with low momentum transfer $Q^2$, but one of the clearest insights we have comes from Chiral Perturbation Theory ($\chi$PT). This effective treatment gives…

In the modern description of nuclear forces based on chiral effective field theory, four-nucleon operators with unknown coupling constants appear. These couplings can be fixed by a fit to the low partial waves of neutron-proton scattering.…

Nuclear Theory · Physics 2011-07-19 Evgeny Epelbaum , Ulf-G. Meißner , Walter Glöckle , Charlotte Elster