We consider nucleon-nucleon (NN) interactions from chiral effective field theory. In this work we restrict ourselves to the elastic NN scattering. We apply the N/D method to calculate the NN partial waves taking as input the one-pion exchange discontinuity along the left-hand cut. This discontinuity is amenable to a chiral power counting as discussed by Lacour, Oller and Meissner [Ann. Phys. (NY) 326, 241 (2011)], with one-pion exchange as its leading order contribution. The resulting linear integral equation for a partial wave with orbital angular momentum L>=2 is solved in the presence of L-1 constraints, so as to guarantee the right behavior of the D and higher partial waves near threshold. The calculated NN partial waves are based on dispersion relations and are independent of regulator. This method can also be applied to higher orders in the calculation of the discontinuity along the left-hand cut and extended to triplet coupled partial waves.
Elastic electron-3He scattering is studied in the relativistic impulse approximation. The amplitudes for the three-nucleon system - 3He - are obtained by solving the relativistic generalization of the Faddeev equation. The charge and magnetic form factor are calculated and compared with the experimental data for the momentum transfer squared up to 100 fm-2. The influence of the various nucleon form factors is investigated.
The effect of the self-energy on the photon-proton elastic scattering is investigated for the backward and the forward directions. The shape of the Thomson scattering at the photon energy $ω\to 0$ is broken by taking into account the self-energy of proton. The electromagnetic polarizabilities $\barα\pm\barβ$ are calculated by the lowest-order perturbative treatment.
Elastic lepton scattering off of a nucleon has proved to be an efficient tool to study the structure of the hadron. Modern cross section and asymmetry measurements at Jefferson Lab require effects beyond the leading order Born approximation to be taken into account. Availability of unpolarized beams of both electrons and positrons in respective experiments would enable to reduce systematic uncertainties due to higher-order charge-odd contributions. In addition, information on an unpolarized electron-to-positron cross section ratio could serve as a test for theoretical models that provide predi…
Within the framework of the improved quantum molecular dynamics model, the medium modifications on the free nucleon-nucleon elastic cross sections are investigated. By using various in-medium nucleon-nucleon elastic cross sections in the model, the nucleon-induced reactions on various targets are simulated, and the excitation functions of reaction cross sections in the energy range from 25 MeV to 1 GeV are calculated. By comparing the calculations with the experimental data, an isospin, density, and momentum-dependence medium correction factor on free nucleon-nucleon elastic cross sections is …
We estimate the target-normal single-spin asymmetry at nearly forward angles in elastic electron-nucleon scattering. In the leading-order approximation, this asymmetry is proportional to the imaginary part of the two-photon exchange (TPE) amplitude, which can be expressed as an integral over the doubly virtual Compton scattering (VVCS) tensor. We develop a model that parametrizes the VVCS tensor for the case of nearly forward scattering angles. Our parametrization ensures a proper normalization of the imaginary part of the TPE amplitude on the well-known forward limit expression, which is give…
We investigate the importance of the three-nucleon (3N) force contact terms in elastic nucleon-deuteron (Nd) scattering by applying the N$^4$LO$^+$ chiral semi-local momentum space (SMS) regularized nucleon-nucleon (NN) chiral potential supplemented by N$^2$LO and all subleading N$^4$LO three-nucleon force (3NF) contact terms. Strength parameters of the contact terms were obtained by least squares fitting of theoretical predictions to cross section and analyzing powers data at three energies of the impinging nucleon. Although the N$^3$LO contributions to the 3N force were completely neglected,…
General expressions for all parity-conserving polarization observables of elastic electron-nucleon scattering in the one-photon exchange approximation are derived for a general frame of reference, i.e.\ not assumming scattering off a nucleon at rest and not specializing to a specific system of coordinates. Essentially, the given expressions are also valid for the inverse process, i.e.\ nucleon scattering off electrons.
We extend our previous study of elastic pion-nucleon scattering in the framework of chiral perturbation theory by performing a combined analysis of the reactions $πN \to πN$ and $πN \to ππN$. The calculation is carried out to fourth order in the chiral expansion using the heavy baryon approach and the covariant formulation supplemented with a modified version of the extended on-mass-shell renormalization scheme. We demonstrate that a combined fit to experimental data in both channels leads to a reduced amount of correlations between the low-energy constants. A satisfactory description of the e…
For the first time, elastic pion-nucleon scattering is analyzed in the framework of chiral perturbation theory up to fourth order with explicit $Δ$ degrees of freedom. The analysis is performed within the heavy-baryon expansion as well as in a covariant approach based on an extended on-mass-shell renormalization scheme. The renormalization of low-energy constants in both chiral approaches is discussed in detail and the explicit expressions to cancel both power-counting breaking as well as decoupling breaking terms are given. The low-energy constants from the $2π\bar{N}N$ interaction as well as…
A systematic study of the in-medium correction factor ($F$) on nucleon-nucleon elastic cross section is performed within the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model. The effects of the beam energy dependence of $F$ on the directed, elliptic flow and nuclear stopping in $^{197}$Au+$^{197}$Au collisions with energy ranging from $0.09$ to $0.8A$ GeV are explored. It is found that the directed, elliptic flow and nuclear stopping at relatively low energies are very sensitive to $F$, and the sensitivity gradually weakens with increasing beam energy. The beam energy dependent in-m…
Quasi-elastic knockout of pions and kaons from nucleons by high-energy electrons and quark microscopy of "soft" meson degrees of freedom in the nucleon
Theoretical uncertainties of various types are discussed for the nucleon-deuteron elastic scattering observables at the incoming nucleon laboratory energies up to 200 MeV. We are especially interested in the statistical errors arising from uncertainties of parameters of a nucleon-nucleon interaction. The obtained uncertainties of the differential cross section and numerous scattering observables are in general small, grow with the reaction energy and amount up to a few percent at 200 MeV. We compare these uncertainties with the other types of theoretical errors like truncation errors, numerica…
