Related papers: Delta--Excitation and Exchange Corrections for NN-…
A model is developed for the hadronic interaction in the two-nucleon system above pion threshold which is based on meson, nucleon and $\Delta$ degrees of freedom and which includes full meson retardation in the exchange operators. For…
We investigate the Dbar-N interaction at low energies using a meson-exchange model supplemented with a short-distance contribution from one-gluon-exchange. The model is developed in close analogy to the meson-exchange KN interaction of the…
We calculate differential cross sections and the spin transfer coefficient $D_{nn}$ in the $\vec{p}+\alpha \to \vec{p}+\alpha+\pi^0$ reaction for proton bombarding energies from 1 to 10 GeV and $\pi^0 - p$ invariant masses spanning the…
First we calculate cross section for the $\gamma p \to \omega p$ reaction from the threshold to very large energies. At low energies the pion exchange is the dominant mechanism. At large energies the experimental cross section can be well…
We study the contribution of the Drell mechanism driven by K^+ and K^- exchange to the reaction gamma N -> KKbar N. Our calculation implements the full KN and KbarN reaction amplitudes in the form of partial wave amplitudes taken from a…
The two-photon-exchange (TPE) contribution in $ep\rightarrow ep\pi ^0$ with $W=M_{\Delta}$ and small $Q^2$ is calculated and its corrections to the ratios of electromagnetic transition form factors $R_{EM} = E_{1+}^{(3/2)}/M_{1+}^{(3/2)} $…
Spectroscopic amplitudes play an important role in nuclear capture reactions. These amplitudes are shown to include both single-particle and polarization effects: the former through their spatial dependence and the latter through their…
We develop the phenomenological amplitude of the $\pi N \to \pi \pi N$ reaction describing the exchanges of $\Delta$ and $N_{*}$ along with the OPE mechanism. The contribution of the latter contains 4 independent low energy parameters (up…
Motivated by the recent paper arXiv:2602.11815 [nucl-th], we calculate in these notes the spectral functions (i.e. imaginary parts) of the NN-potentials as they arise from $2\pi$-exchange with single and double Roper resonance excitation.…
A recent argument of Oerding shows that our calculation of the quantity Delta, which determines the amplitude of the asymptotic decay of the particle density in d < 2 < 4, was in error. Instead it is simply given by Delta = n_0, the initial…
We present a calculation of the N to $\Delta$ electromagnetic transition amplitudes using the method of QCD sum rules. A complete set of QCD sum rules are derived for the entire family of transitions from the baryon octet to decuplet. They…
One-loop corrections to $\omega$ photoproduction near threshold have been investigated by using the approximation that all relevant transition amplitudes are calculated from the tree diagrams of effective Lagrangians. With the parameters…
The nuclear cross sections for charged lepton production induced by $\beta$ beam neutrinos (anti-neutrinos) in $^{16}$O have been presented at intermediate energies corresponding to the Lorentz boost factor $\gamma<250 (150)$. The…
The first-order bremsstrahlung emission spectrum is $\alpha d\omega/\omega$ at zero temperature. If the radiation is emitted into a region that contains a thermal distribution of photons, then the rate is increased by a factor $1+N(\omega)$…
We compare a recent lattice determination of the nucleon distribution amplitudes with other approaches and models. We study the nucleon distribution amplitudes up to twist 6 in next-to leading conformal spin and we also investigate…
The large two-pion exchange amplitudes are calculated in HB$\chi$PT and their net contribution to the reaction cross section is large.
Previous calculations of the polarizabilities of the nucleon within the framework of heavy baryon chiral perturbation theory have included the contribution of the $\Delta$(1232) only its effect on various contact terms or have been…
The charge-exchange break-up of polarised deuterons pol{d}p -> {pp}n, where the final {pp} diproton system has a very low excitation energy and hence is mainly in the 1S0 state, is a powerful tool to probe the spin-flip terms in the…
We study the effects of the $\Delta$(1232) resonance as an effective degree of freedom for charged and neutral pion photo-production on nucleons. Different observables have been calculated for these processes by using relativistic chiral…
The recently obtained experimental result for the quenching of the GT sum rule in the reaction ^90Zr(p,n)^90Nb is used to extract the value of the Landau-Migdal parameter g_{N\Delta}', taking into account also the effect of the finite range…