Related papers: Probing Delta structure with pion electromagnetic …
Coherent photoproduction of $\pi^0$-mesons from threshold ($E_{th} \approx$ 136 MeV) throughout the $\Delta$-resonance region and of $\eta$-mesons close to the production threshold ($E_{th} \approx$ 570 MeV for $\eta$) has been measured for…
It is believed that one can extract more accurate information of the pion distribution amplitude from the pion-photon transition form factor (TFF) due to the single pion in this process. However the BABAR and Belle data of the pion-photon…
High-precision H(e,e'p)pi0 measurements at Q2=0.126 (GeV/c)2 are reported, which allow the determination of quadrupole amplitudes in the gamma* N->Delta transition; they simultaneously test the reliability of electroproduction models. The…
The decay Delta^+ --> p gamma is studied in the 1/N_c expansion of QCD. The ratio of the helicity amplitudes is determined to be A_{3/2}/A_{1/2} = \sqrt{3} + O(1/N_c^2). Equivalently, the ratio E2/M1 of the multipole amplitudes is predicted…
We investigate the pion photoproduction in the \Delta(1232) region in the framework of an effective Lagrangian including pions, nulceon and \Delta(1232). We work to third order in a small scale expansion with both $m_{\pi}$ and…
The multipole content of pion photoproduction at the $\Delta^+ (1232)$ resonance has been extracted from a data set dominated by recent Mainz Microtron (MAMI) precision measurements. The analysis has been carried out in the Athens Model…
The availaible data on the D0 to K0S pi+ pi- decays are analysed in the framework of the quasi two-body QCD factorization approximation. The annihilation, via W-exchange, amplitudes are added to the weak-decay tree amplitudes. The doubly…
In kaon decay, electromagnetic radiative corrections can generate shifts in the apparent Delta I = 3/2 amplitude of order alpha A_0/A_2 ~ 22 alpha. In order to know the true Delta I = 3/2 amplitude for comparison with lattice calculations…
Pion photoproduction reactions are investigated in a dynamical coupled-channel approach based on the Juelich pi-N model, which presently includes the hadronic pi-N and eta-N stable channels as well as the pi-Delta, sigma-N and rho-N…
The holographic QCD prediction for the pion distribution amplitude (DA) $\phi_{hol}(u)$ is used to compute the pion spacelike electromagnetic form factor $F_{\pi}(Q^2)$ within the QCD light-cone sum rule method. In calculations the pion's…
The electromagnetic pion production reactions are investigated within the dynamical coupled-channels model developed in {\bf Physics Reports, 439, 193 (2007)}. The meson-baryon channels included in this study are $\gamma N$, $\pi N$, $\eta…
We develop techniques to calculate the four Delta electromagnetic form factors using lattice QCD, with particular emphasis on the sub-dominant electric quadrupole form factor that probes deformation of the Delta. Results are presented for…
We provide a successful fit for proton-neutron scattering below pion production threshold up to LAB energies of 350 MeV. We use seven high-quality fits based on potentials with different forms as a measure of the systematic uncertainty. We…
We present the results on P11 resonances obtained with Dubna-Mainz-Taipei (DMT) dynamical model for pion-nucleon scattering and pion electromagnetic production. The extracted values agree well, in general, with PDG values. One pole is found…
We report on the investigation of $\Delta$(1232) production and decay in proton-proton collisions at a kinetic energy of 1.25 GeV measured with HADES. Exclusive dilepton decay channels $ppe^{+}e^{-}$ and $ppe^{+}e^{-}\gamma$ have been…
Right now, we have not enough knowledge to determine the hadron distribution amplitudes (DAs) which are universal physical quantities in the high energy processes involving hadron for applying pQCD to exclusive processes. Even for the…
We study the weak production of $\Delta$ (i.e. $e^{-} + p \to \Delta^{0}+ \nu_{e}$ and $e^{+} + p \to \Delta^{++} + \bar{\nu}_{e}$) in the intermediate energy range corresponding to the Mainz and TJNAF electron accelerators. The…
The $\Delta(1232) \to \gamma^\ast N$ magnetic dipole form factor ($G_M^\ast$) is described here within a new covariant model that combines the valence quark core together with the pion cloud contributions. The pion cloud term is…
We present results on the electroexcitation of the low mass resonances Delta(1232)P33, N(1440)P11, N(1520)D13, and N(1535)S11 in a wide range of Q2. The results were obtained in the comprehensive analysis of JLab-CLAS data on differential…
We report new precise H$(e,e^\prime p)\pi^0$ measurements at the $\Delta(1232)$ resonance at $Q^2= 0.127$ (GeV/c)$^2$ using the MIT/Bates out-of-plane scattering (OOPS) facility. The data reported here are particularly sensitive to the…