相关论文: Evaluation of the Pion-Nucleon Sigma Term from CHA…
The number of sigma of confidence in a determination of the neutrino mass hierarchy may be obtained from the statistic Delta chi squared. However, as the hierarchy is a discrete variable, this number is not given by the usual square root…
We review progress in studying two central problems in Nuclear Astrophysics: The \be7pg reaction is one of the major source of uncertainties in estimating the \b8 solar neutrino flux and is critical for the Solar Neutrino Problem. We…
We include two new three-nucleon-force terms of pion-range - short-range form in our momentum-space calculations for the three-nucleon continuum. These two terms are expected by chiral perturbation theory to be non-negligible. We study the…
We undertake a covariance error analysis of the pion-nucleon-nucleon coupling constants from the Granada-2013 np and pp database comprising a total of 6720 scattering data below LAB energy of 350 MeV. Assuming a unique pion-nucleon coupling…
We calculate the one--loop contributions of order $M_\pi^4$ to the difference $\Delta_R$ between the on--shell pion--nucleon scattering amplitude $\bar{D}^+(0,2M_\pi^2)$ at the Cheng--Dashen point $\nu =0$, $t=2M_\pi^2$ and the scalar form…
The measurement of the pion-nucleon scattering lengths constitutes a high-precision test of the methods of Chiral Pertubation Theory, which is the low-energy approach of QCD. The pion-nucleon s-wave scattering lengths are related to the…
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…
We determine the nucleon axial, scalar and tensor charges and the nucleon $\sigma$-terms using twisted mass fermions. We employ three ensembles with approximately equal physical volume of about 5.5~fm, three values of the lattice spacing,…
The coupled eta-N, pi-N, gamma-N system is described by a K-matrix method. The parameters in this model are adjusted to get an optimal fit to pi-N --->pi- N$, pi-N --->eta-N$, gamma-N--->pi-N and gamma-N --->eta-N data in an energy range of…
The CERN COMPASS experiment can use 100-280 GeV pion and kaon beams and magnetic spectrometers and calorimeters to measure Hybrid (mixed quark-gluon) meson production cross sections in the Primakoff scattering of high energy pions and kaons…
Within the post-form distorted wave Born approximation wherein pure Coulomb, pure nuclear and their interference terms are treated consistently in a single setup we study the beam energy dependence of the Coulomb-nuclear interference terms…
The total cross sections for pionic charge exchange on hydrogen were measured using a transmission technique on thin CH2 and C targets. Data were taken for pi- lab energies from 39 to 247 MeV with total errors of typically 2% over the…
Consider high energy (GeV) beam particles scattering from the Coulomb field of a target nucleus (Z, A). The Coulomb field acts as a target of $\gamma^*$ virtual photons, with the target density proportional to Z$^2$. Henry Primakoff was the…
Fermilab E781 plans measurements of gamma-Sigma and $\gamma$-pion interactions using a 600 GeV beam of Sigmas and pions, and a virtual photon target. Pion polarizabilities and radiative transitions will be measured in this experiment. The…
The in-medium properties of a hyperon-nucleon potential, derived within chiral effective field theory and fitted to Lambda-N and Sigma-N scattering data, are investigated. Results for the single-particle potentials of the Lambda and Sigma…
Using heavy-baryon chiral perturbation theory, we have calculated all the diagrams up to two-loop order which contribute to the S-wave pion self-energy in symmetric nuclear matter. Some subtleties related to the definition of pion fields…
We propose a novel way to formulate Chiral Perturbation Theory in a nuclear background, characterized by a static, non-uniform distribution of the baryon number that describes the finite nucleus. In the limiting case of a uniform…
We analyze Pion Nucleon Scattering up to 700 MeV using a simple, relativistic, unitary model\cite{1}. The kernel of the integral equation includes nucleon, roper, delta, D_13 as well as S_11 poles with their corresponding crossed pole terms…
In this work, we develop an updated model for pion-nucleus scattering in the framework of the distorted wave impulse approximation in momentum space. We construct the second-order pion-nucleus potential, which involves analysis of…
Nucleon-nucleon scattering in spin-triplet channels is analysed within an effective field theory where one-pion exchange is treated nonperturbatively. Justifying this requires the identification of an additional low-energy scale in the…