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We give predictions for the partial wave amplitudes of pion photoproduction near threshold by means of dispersion relations at fixed t. The free parameters of this approach are determined by a fit to experimental data in the energy range…

Nuclear Theory · Physics 2016-09-08 O. Hanstein , D. Drechsel , L. Tiator

Photoproduction of two pions on nucleon and deuteron is studied for photon energies from threshold up to $E_\gamma = 1.5$ GeV. For the elementary operator an effective Lagrangean approach is used with resonance and Born contributions. The…

Nuclear Theory · Physics 2020-05-20 A. Fix , H. Arenhoevel

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…

High Energy Physics - Phenomenology · Physics 2019-11-27 Gustavo H. Guerrero Navarro , Astrid N. Hiller Blin , M. J. Vicente Vacas , De-Liang Yao

The double pion photoproduction off nucleons near threshold is analyzed in a covariant baryon chiral perturbation theory up to next to leading order, where the $\Delta(1232)$, $N^*(1400)$ and $\rho(770)$ resonances are included as explicit…

High Energy Physics - Phenomenology · Physics 2025-01-07 Kai-Ge Kang , Xiong-Hui Cao , De-Liang Yao , Han-Qing Zheng

We present a calculation of $\pi^0$ photoproduction on the proton in manifestly Lorentz-invariant baryon chiral perturbation theory up to and including chiral order $q^4$. With the results we analyze the latest $\pi^0$ photoproduction data…

Nuclear Theory · Physics 2015-06-12 Marius Hilt , Stefan Scherer , Lothar Tiator

We analyze the new threshold data for neutral pion photoproduction off protons in the framework of heavy baryon chiral perturbation theory. We show that large loop corrections are needed to understand the S--wave multipole $E_{0+}$ and that…

High Energy Physics - Phenomenology · Physics 2009-10-28 V. Bernard , N. Kaiser , Ulf-G. Meißner

Some open topics in the field of low energy photon-nucleon interactions are discussed--which in my opinion are of interest both for obtaining new information on nucleon structure as well as for precision tests of our theoretical…

Nuclear Theory · Physics 2007-05-23 Thomas R. Hemmert

We summarize the pertinent experimental and theoretical developments in the field of pion photo- and electroproduction in the threshold region. We discuss which experiments and which calculations should be done/performed in the future.

Nuclear Theory · Physics 2009-10-28 Ulf-G. Meißner , B. Schoch

I summarize three recent calculations of electromagnetic reactions on deuterium in chiral perturbation theory. All of these calculations were carried out to O(Q^4), i.e. next-to-next-to-leading order. The reactions discussed here are:…

Nuclear Theory · Physics 2009-11-07 Daniel Phillips

Neutral current single pion production induced by neutrinos and antineutrinos on nucleon targets has been investigated in manifestly relativistic baryon chiral perturbation theory with explicit $\Delta(1232)$ degrees of freedom up to…

High Energy Physics - Phenomenology · Physics 2019-06-04 De-Liang Yao , Luis Alvarez-Ruso , M. J. Vicente Vacas

There is evidence that the photoproduction of single and double pions off bound nucleons inside a nucleus are not only affected by Fermi motion but also by other nuclear effects, such as final state interactions or meson rescattering. We…

Nuclear Experiment · Physics 2011-09-01 Manuel Dieterle

An effective field theory with hadrons and photons is constructed, where the hadronic parameters are determined by fitting elastic $\pi$N scattering data. The predicted pion-induced $\eta$-production on the nucleon agrees well with the…

Nuclear Theory · Physics 2011-04-15 C. Sauermann , B. L. Friman , W. Nörenberg

I review recent progress made in the description of pion-nucleon scattering, the $\sigma$--term, the scalar form factor and the strangeness content of the nucleon in the framework of heavy baryon chiral perturbation theory. Other topics are…

High Energy Physics - Phenomenology · Physics 2011-04-15 Ulf-G. Meißner

The pion and nucleon mass differences generate a very pronounced cusp in the photoproduction reaction of a single neutral pion on the proton. A nonrelativistic effective field theory to describe this reaction is constructed. The approach is…

High Energy Physics - Phenomenology · Physics 2014-11-20 Andreas Fuhrer

The photoproduction of a neutral pion on the deuteron is considered in the energy region around the eta threshold, where a bump-like structure was observed at very backward pion angles. Different dynamical aspects which may be responsible…

Nuclear Theory · Physics 2009-11-11 A. Fix

I review aspects of chiral dynamics pertinent to the structure of baryons and few-nucleon systems, such as chiral extrapolations for the nucleon and the delta mass, double pion photoproduction off protons, single neutral pion…

High Energy Physics - Phenomenology · Physics 2007-05-23 Ulf-G. Meißner

We explore the photoproduction mechanisms for charged and neutral pion pairs off a heavy nucleus at threshold. We calculate the production of charged pairs in the Coulomb field of the nucleus in the Born approximation using explicit…

Nuclear Theory · Physics 2022-06-22 S. Gevorkyan , I. Larin , R. Miskimen , E. Smith

Photoproduction of neutral pions from nuclei (carbon, calcium, niobium, lead) has been studied for incident photon energies from 200 MeV to 800 MeV with the TAPS detector using the Glasgow photon tagging spectrometer at the Mainz MAMI…

I review the interesting tale of the electric dipole amplitude in neutral pion photoproduction and the resulting consequences. I also discuss why there is new life related to P--wave multipoles. Electroproduction is briefly touched upon.

High Energy Physics - Phenomenology · Physics 2007-05-23 Ulf-G. Meißner

In this paper we study coherent neutrinoproduction of photons [neutral current (NC)] and pions [charged current (CC) and NC] with $E_{\nu} \leqslant 0.5 $ GeV. The production from nucleons and incoherent production with $E_{\nu} \leqslant…

Nuclear Theory · Physics 2012-10-01 Xilin Zhang , Brian D. Serot