Related papers: Hyperon forward spin polarizabilty gamma0
The generalized forward spin polarizabilities $\gamma_0$ and $\delta_{LT}$ of the neutron have been extracted for the first time in a $Q^2$ range from 0.1 to 0.9 GeV$^2$. Since $\gamma_0$ is sensitive to nucleon resonances and $\delta_{LT}$…
We formulate a new power-counting scheme for a chiral effective field theory of nucleons, pions, and Deltas. This extends chiral perturbation theory into the Delta-resonance region. We calculate nucleon Compton scattering up to…
A brief review of Compton scattering off the deuteron in Chiral Effective Field Theory, including gauge invariance and the correct Thomson limit. We model-independently determine the iso-scalar, spin-independent dipole polarisabilities of…
We discuss a recent computation of Compton scattering on the deuteron at photon energies of order the pion mass. An interaction kernel is computed in baryon chiral perturbation theory and sewn to phenomenological deuteron wave functions. As…
A measurement of parity-violating spin-dependent gamma proton Compton scattering will provide a theoretically clean determination of the parity-violating pion-nucleon coupling constant $h_{\pi NN}^{(1)}$. We calculate the leading…
Proton Compton scattering is analyzed with the chiral Lagrangian. Partial-wave amplitudes are obtained by an analytic extrapolation of subthreshold reaction amplitudes computed in chiral perturbation theory, where the constraints set by…
An effective field theory is used to give a model-independent description of Compton scattering at energies comparable to the pion mass. The amplitudes for scattering on the proton and the deuteron, calculated to fourth order in small…
The leading order contributions of processes involving anomalous pion-photon vertices to forward spin-dependent Compton scattering from nucleons are considered in heavy-baryon chiral perturbation theory. These all involve the exchange of…
Compton scattering results are used to probe proton structure via measurement of higher order polarizabilities. Values for $\alpha_{E2}^p,\beta_{E2}^p,\alpha_{E\nu}^p,$ $\beta_{E\nu}^p$ determined via dispersion relations are compared to…
Compton scattering on the deuteron is studied in the framework of baryon chiral perturbation theory to third order in small momenta, for photon energies of order the pion mass. The scattering amplitude is a sum of one- and two-nucleon…
The status of Compton scattering by the nucleon at energies of the first and second resonance is summarized. In addition to a general test of dispersion theories and a precise determination of polarizabilities, the validities of four…
We calculate the complete $T$ matrices with decuplet contributions for pion-nucleon scattering to order $\mathcal{O}(\epsilon^3)$ in heavy baryon SU(3) chiral perturbation theory. The baryon mass in the chiral limit $M_0$ and the low-energy…
We calculate the forward spin-dependent photon-nucleon Compton amplitude as a function of photon energy at the next-to-leading (${\cal O}(p^4)$) order in chiral perturbation theory, from which we extract the contribution to nucleon spin…
The proton polarizability effect in the muonic-hydrogen Lamb shift comes out as a prediction of baryon chiral perturbation theory at leading order and our calculation yields for it: $\Delta E^{(\mathrm{pol})} (2P-2S) = 8^{+3}_{-1}\, \mu$eV.…
We analyse the angular distributions of the Sigma^0 --> Lambda^0 + gamma decay rate in the laboratory and in the rest frame of the Sigma^0 - hyperon in the dependence on baryon polarizations. We calculate the dynamical polarization vector…
We study baryon-baryon scattering by applying time-ordered perturbation theory to the manifestly Lorentz-invariant formulation of SU(3) baryon chiral perturbation theory. We derive the corresponding diagrammatic rules paying special…
We present the leading-order prediction of baryon chiral perturbation theory for the proton polarizability contribution to the 2S hyperfine splitting in muonic hydrogen, and compare with the results of dispersive calculations.
We calculate the nucleons' electromagnetic polarizabilities in heavy baryon chiral perturbation theory including all terms to order ${\cal O} (q^4)$. The chiral prediction of the electric polarizabilities for the neutron and the proton are…
We propose to access the gluon polarization $\Delta G$ by measuring the cross section spin-asymmetry in semi-inclusive polarized lepton -- nucleon scattering. The photon-gluon fusion sub-process will be tagged by detecting high-$p_T$…
We present recent results on elastic deuteron Compton scattering calculations for polarised beans and targets up to next-to-leading order within Chiral Effective Field Theory in the Small Scale Expansion variant to implement a dynamical…