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We compute the neutron-neutron relative-energy distribution of the triton following the hard knockout of the proton in pionless effective field theory. This distribution can be used to study universality as well as to obtain information on…

Nuclear Theory · Physics 2025-05-28 Tanja Kirchner , Matthias Göbel , Hans-Werner Hammer

We examine the results of Chiral Effective Field Theory ($\chi$EFT) for the scalar- and spin-dipole polarisabilities of the proton and neutron, both for the physical pion mass and as a function of $m_\pi$. This provides chiral…

Nuclear Theory · Physics 2016-07-15 Harald W. Griesshammer , Judith A. McGovern , Daniel R. Phillips

The neutron-neutron fusion process, $nn\to de\nu$, at very low neutron energies is studied in the framework of pionless effective field theory that incorporates dibaryon fields. The cross section and electron energy spectrum for this…

Nuclear Theory · Physics 2009-11-11 Shung-ichi Ando , Kuniharu Kubodera

Next to leading order effective field theory calculations are performed for $ {}^1S_0$ NN scattering using subtractive renormalization procedure. One pion exchange and contact interaction potentials are iterated using Lippman-Schwinger…

Nuclear Theory · Physics 2009-10-31 J. Gegelia

We present a new evaluation of the negatively charged pion mass based on the simultaneous spec-troscopy of pionic nitrogen and muonic oxygen transitions using a gaseous target composed by a N 2 /O 2 mixture at 1.4 bar. We present the…

The properties of low-energy neutron-proton systems are studied in an effective field theory where only nucleons figure as relevant degrees of freedom. With a finite momentum cut-off regularization scheme, we show that the large scattering…

High Energy Physics - Phenomenology · Physics 2007-05-23 Tae-Sun Park

We present a comprehensive theoretical study of low-energy few nucleon scattering for systems with $A\leq 4$. To this end, we utilize pionless effective field theory, which we employ at next-to-leading order. We show that at this level the…

Nuclear Theory · Physics 2023-06-09 Martin Schäfer , Betzalel Bazak

Low energy theorems have been derived for the coefficients of the effective range expansion in s-wave nucleon-nucleon scattering valid to leading nontrivial order in an expansion based $Q$ counting, a scheme in which both $m_\pi$ and $1/a$…

Nuclear Theory · Physics 2009-10-31 Thomas D. Cohen , James M. Hansen

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…

Nuclear Theory · Physics 2019-01-18 Feng-Kun Guo , Chien-Yeah Seng

An effective field theory treatment of nucleon-nucleon scattering at low energy shows much promise and could prove a useful tool in the study of nuclear matter at both ordinary and extreme densities. The analysis is complicated by the…

Nuclear Theory · Physics 2009-10-30 David B. Kaplan

In this article I summarize recent progress in the effective field theory approach to low energy nuclear systems, with a focus on the power counting issue. In the pionless sector, where the power counting is quite well understood at the…

Nuclear Theory · Physics 2020-04-22 C. -J. Yang

An analytic expression for the ${}^1S_0$ phase shifts in nucleon-nucleon scattering is derived in the context of the Schr\"odinger equation in configuration space with a short distance cutoff and with a consistent power counting scheme…

Nuclear Theory · Physics 2009-10-31 Thomas D. Cohen , James M. Hansen

Peripheral nucleon-nucleon scattering is analysed in the framework of an effective field theory. Distorted-wave methods are used to remove the effects of one-pion exchange. Two-pion exchange and recoil corrections to one-pion exchange are…

Nuclear Theory · Physics 2009-11-10 Michael C. Birse , Judith A. McGovern

We use the framework of effective field theories to discuss the determination of the S-wave \pi N scattering lengths from the recent high-precision measurements of pionic deuterium observables. The theoretical analysis proceeds in several…

Nuclear Theory · Physics 2014-11-18 Ulf-G. Meißner , Udit Raha , Akaki Rusetsky

The 3S1-3D1 mixing angle for nucleon-nucleon scattering, epsilon_1, is calculated to next-to-next-to-leading order in an effective field theory with perturbative pions. Without pions, the low energy theory fits the observed epsilon_1 well…

Nuclear Theory · Physics 2009-10-31 Sean Fleming , Thomas Mehen , Iain W. Stewart

Compared in this work are a few sets of results, obtained from the pion-nucleon ($\pi N$) data at low energy (pion laboratory kinetic energy up to $100$ MeV) on the basis of the modelling of the $s$- and $p$-wave $K$-matrix elements (or of…

Nuclear Theory · Physics 2022-06-07 Evangelos Matsinos

We perform Bayesian model calibration of two-nucleon ($NN$) low-energy constants (LECs) appearing in an $NN$ interaction based on pionless effective field theory (EFT). The calibration is carried out for potentials constructed using naive…

Nuclear Theory · Physics 2024-08-06 J. M. Bub , M. Piarulli , R. J. Furnstahl , S. Pastore , D. R. Phillips

The extraction of the isovector s-wave pi N amplitude from pionic atoms is studied with special emphasis on uncertainties and their dependence on the assumptions made regarding the neutron density distributions in nuclei and on the size of…

Nuclear Theory · Physics 2009-11-10 E. Friedman , A. Gal

I outline the effective field theory (EFT) calculation of nucleon-nucleon scattering which was recently carried out to next-to-next-to-leading order (NNLO) by Noam Shoresh and myself. In this calculation only potential pion contributions…

Nuclear Theory · Physics 2007-05-23 G. Rupak , N. Shoresh

We present the results of a third order calculation of the pion-nucleon scattering amplitude in a chiral effective field theory with pions, nucleons and delta resonances as explicit degrees of freedom. We work in a manifestly Lorentz…

High Energy Physics - Phenomenology · Physics 2016-05-25 De-Liang Yao , D. Siemens , V. Bernard , E. Epelbaum , A. M. Gasparyan , J. Gegelia , H. Krebs , Ulf-G. Meißner