Related papers: Radiative pion capture by a nucleon
As a guideline for future experiments to extract the four (leading) spin polarizabilities of the nucleon, we have constructed the forward amplitude for polarized Compton scattering by dispersion integrals. These integrals have been…
We consider two methods to find the effective parameters of the pion traversing a nuclear medium. One is the first order chiral perturbation theoretic evaluation of the pion pole contribution to the two-point function of the axial-vector…
We calculate the Gaussian radius parameters of the pion-emitting source in high energy heavy ion collisions, assuming a first order phase transition from a thermalized Quark-Gluon-Plasma (QGP) to a gas of hadrons. Such a model leads to a…
A measurement is presented of the exclusive and semi-exclusive production of charged pion pairs in proton-proton collisions, pp to p(p*) + $\pi^+\pi^-$ + p(p*) here the $\pi^+\pi^-$ pair is emitted at central rapidities, and the scattered…
The $^{1}$H($e,e^\prime \pi^+$)n cross section was measured for a range of four-momentum transfer up to $Q^2$=3.91 GeV$^2$ at values of the invariant mass, $W$, above the resonance region. The $Q^2$-dependence of the longitudinal component…
We perform a precision study of radii in Boron isotopes for multiple realistic interactions from chiral effective field theory. We obtain predictions of radii with combined many-body and interaction uncertainty quantification from ab initio…
We present the results of a third order calculation of the pion-nucleon scattering amplitude in a chiral effective field theory with pions, nucleons and delta resonances as explicit degrees of freedom. We work in a manifestly Lorentz…
Total and partial cross sections for breakup of ground rovibronic state of H$_2^+$by photon impact are calculated using the exact nonadiabatic nonrelativistic Hamiltonian without approximation. The converged results span six orders of…
The relativistic field theory model of the deuteron is applied to the calculation of the cross sections of the low-energy radiative neutron-proton capture n + p -> D + gamma and the low-energy two-proton fusion p + p -> D + e^+ + nu_e. For…
We study the low energy pion-hyperon interaction considering effective non-linear chiral invariant Lagrangians including pions, rho mesons, hyperons and corresponding resonances. Then we calculate the S- and P-wave phase-shifts, total cross…
A reliable calculation of radiative corrections to $\tau\to\pi\pi\nu_\tau$ decays is an important prerequisite for using hadronic $\tau$ decays for a data-driven evaluation of the hadronic-vacuum-polarization contribution to the anomalous…
We present results on spectra of pions, kaons and (anti)protons from a study of heavy ion collisions using the perturbative QCD + saturation model to calculate the production of initial (transverse) energy and baryon number followed by a…
Understanding pion production in nucleon-nucleon collisions near threshold has been a challenge for the last decades. In particular, the reaction pp -> pppi0 is highly sensitive to short-range mechanisms, because isospin conservation…
The leading twist parametrization of dipion mass distribution in hard exclusive reactions is proposed. Its parameters are related to quark distributions (usual and skewed) in the pion and to distributions amplitudes of mesons ($\pi$,…
Preliminary results of the strong interaction shift and width in pionic hydrogen ($\pi H$) using an X-ray spectrometer with spherically bent crystals and CCDs as X-ray detector are presented. In the experiment at the Paul Scherrer Institute…
Formal expressions are developed for the general five-fold differential cross section of incoherent $\pi$-photoproduction on the deuteron including beam and target polarization. The polarization observables of the cross section are…
Using dispersion theory the low-energy electromagnetic form factors for the transition of a Sigma to a Lambda hyperon are related to the pion vector form factor. The additionally required input, i.e. the two-pion--Sigma--Lambda amplitudes…
A forward dispersion calculation is implemented for the spin polarizabilities $\gamma_1, ... ,\gamma_4$ of the proton and the neutron. These polarizabilities are related to the spin structure of the nucleon at low energies and are…
Effective field theory techniques are used to describe the interaction of heavy hadrons in a model independent way. Predictability is obtained by exploiting the symmetries of QCD. Heavy hadron chiral perturbation theory is reviewed and used…
The differential cross sections for the process $\gamma \gamma \to \pi^0 \pi^0$ have been measured in the kinematic range 0.6 GeV $< W < 4.1$ GeV, $|\cos \theta^*|<0.8$ in energy and pion scattering angle, respectively, in the…