相关论文: Probing Delta structure with pion electromagnetic …

We describe the present status of the pion distribution amplitude (DA) as it originates from several sources: (i) a nonperturbative approach based on QCD sum rules with nonlocal condensates, (ii) an $O(\alpha_s)$ QCD analysis of the CLEO…

Using the delta-shell representation we present a successful fit to neutron-proton and proton-proton scattering data below pion production threshold. A detailed overview of the theory necessary to calculate observables with this potential…

Within a dynamical model, rescattering effects are studied in coherent pion photoproduction on the deuteron in the $\Delta$(1232) resonance region. The model consists of a system of coupled equations for the N$\Delta$, NN$\pi$ and NN…

We consider two-photon exchange (TPE) in the elastic electron-proton scattering and evaluate the effect of \pi N (pion + nucleon) intermediate hadronic states. Among different \pi N states, we concentrate on the P33 channel; thus we…

The thermodynamic potential of a system of pions and nucleons is computed including the piN interactions in the P33 channel. A consistent treatment of the width of the resonance in this channel, the Delta(1232) resonance, is explored in…

A method suitable for extracting resonance parameters of unstable baryons in lattice QCD is examined. The method is applied to the strong decay of the Delta to a pion-nucleon state, extracting the pi-N - Delta coupling constant and Delta…

The helicity-dependent single $\pi^{0}$ photoproduction cross section on the deuteron and the angular dependence of the double polarisation observable $E$ for the quasi-free single $\pi^0$ production off the proton and the neutron have been…

The muon decay parameter delta has been measured by the TWIST collaboration. We find delta = 0.74964 +- 0.00066(stat.) +- 0.00112(syst.), consistent with the Standard Model value of 3/4. This result implies that the product Pmuxi of the…

We report measurements of the exclusive neutral pion electroproduction cross section off protons at large values of $x_B$ (0.36, 0.48 and 0.60) and $Q^2$ (3.1 to 8.4 GeV$^2$) obtained from Jefferson Lab Hall A experiment E12-06-014. The…

Deeply virtual electroproduction of pion in exclusive reaction $p(e,e'\pi^+)n$ is studied using a two-component model which includes soft hadronic and hard partonic reaction mechanisms. The results are compared with the experimental data…

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.…

The parity-violating (PV) asymmetry of inclusive $\pi^-$ production in electron scattering from a liquid deuterium target was measured at backward angles. The measurement was conducted as a part of the G0 experiment, at a beam energy of 360…

Within the previously developed Dubna-Mainz-Taipei meson-exchange model, the singularity structure of the pi N scattering amplitudes has been investigated. For all partial waves up to F waves and c.m. energies up to W = 2 GeV, the T-matrix…

MAID is a unitary isobar model for a partial wave analysis of pion photo- and electroproduction in the resonance region. It is fitted to the world data and can give predictions for multipoles, amplitudes, cross sections and polarization…

We show that constraints from perturbative QCD calculations play a role in the nucleon to Delta(1232) electromagnetic transition even at moderate momentum transfer scales. The pQCD constraints, tied to real photoproduction data and…

We examine the role of the Delta-Delta intermediate state in low energy NN scattering using effective field theory. Theories both with and without pions are discussed. They are regulated with dimensional regularization and MSbar…

The $\gamma^\ast \gamma \to \pi^0$ transition form factor, $G(Q^2)$, is computed on the entire domain of spacelike momenta using a continuum approach to the two valence-body bound-state problem in relativistic quantum field theory: the…

We study the hard exclusive production of two pions in the virtual photon fragmentation region with various invariant masses including the resonance region. The amplitude is expressed in terms of two-pion light cone distribution amplitudes…

Pion photoproduction off the nucleon close to threshold is studied in covariant baryon chiral perturbation theory at O($p^3$) in the extended-on-mass-shell scheme, with the explicit inclusion of the $\Delta(1232)$ resonance using the…

We present the results on the ratios $E_{1+}^{(3/2)}/M_{1+}^{(3/2)}$ and $S_{1+}^{(3/2)}/M_{1+}^{(3/2)}$ for the $\gamma^* N \to \Delta(1232)$ transition at $Q^2\leq 4 (GeV/c)^2$ extracted from the $p(e,e'p)\pi^0$ cross section using two…