Related papers: Pion Polarizabilities at CERN COMPASS
Recent experimental pion polarizability data are reviewed and analyzed. Data on the radiative \pi^+ meson photoproduction on the proton at MAMI has been used to determine the difference of the electric and magnetic dipole polarizabilities…
The values of charged pion polarizabilities obtained in the framework of chiral perturbation theory at the level of two-loop accuracy are compared with the experimental result recently reported by COMPASS Collaboration. It is found that the…
The electromagnetic polarizabilities of the nucleon are fundamental nucleon-structure observables that characterize its response to external electromagnetic fields. The neutron polarizabilities can be accessed from Compton-scattering data…
We present results for the charged and neutral pion polarizabilities, obtained through a dispersive analysis of photon-fusion reactions with two pions in the final state. This analysis is motivated by current and future measurements at…
We update the predictions of the SU(2) baryon chiral perturbation theory for the dipole polarisabilities of the proton, $\{\alpha_{E1},\,\beta_{M1}\}_p=\{11.2(0.7),\,3.9(0.7)\}\times10^{-4}$fm$^3$, and obtain the corresponding predictions…
The scalar dipole polarizabilities, $\alpha_{E1}$ and $\beta_{M1}$, are fundamental properties related to the internal dynamics of the nucleon. The currently accepted values of the proton polarizabilities were determined by fitting to…
A status report on the topic Compton scattering and polarizabilities is presented with emphasis on the scalar t-channel as entering into dispersion theory. Precise values for the polarizabilities are obtained leading to $\alpha_p = 12.0\pm…
Starting from hyperbolic dispersion relations, we derive a system of Roy--Steiner equations for pion Compton scattering that respects analyticity, unitarity, gauge invariance, and crossing symmetry. It thus maintains all symmetries of the…
The Compton scattering cross section on the proton has been measured at laboratory angles of 90$^\circ$ and 135$^\circ$ using tagged photons in the energy range 70--100 MeV and simultaneously using untagged photons in the range…
Measuring Compton scattered photons and recoil neutrons in coincidence, quasi-free Compton scattering by the neutron has been investigated at MAMI (Mainz) at $theta^{lab}_\gamma=136^o$ in an energy range from 200 to 400 MeV. From the data a…
The spin polarizabilities of the nucleon describe how the spin of the nucleon responds to an incident polarized photon. The most model-independent way to measure the nucleon spin polarizabilities is through polarized Compton scattering.…
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…
Electromagnetic polarizabilities are important parameters for understanding the interaction between photons and hadrons. For pions these quantities are poorly constrained experimentally since they can only be measured indirectly. New…
As guideline for forthcoming experiments, we present predictions from Chiral Effective Field Theory for polarized cross sections in low energy Compton scattering for photon energies below 170 MeV, both on the proton and on the neutron.…
Compton scattering by the proton has been measured over a wide range covering photon energies 250 MeV < E_\gamma < 800 MeV and photon scattering angles 30^0 < \theta^{lab}_\gamma < 150^0, using the tagged-photon facility at MAMI (Mainz) and…
Motivated by developments at HIGS at TUNL that include increased photon flux and the ability to circularly polarize photons, we calculate several beam-polarization/target-spin dependent observables for elastic Compton scattering on the…
We review the cross sections for low-energy $\pi^- \gamma$ reactions in the framework of chiral perturbation theory. Charged pion Compton scattering, $\pi^- \gamma\to \pi^-\gamma$, is considered up to one-loop order where the pion's…
Based on Compton scattering and meson photoproduction data the polarizabilities of the nucleon are precisely studied and well understood due to recent experimental and theoretical work based on nonsubtracted dispersion relations. The {\it…
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…
An analysis of all experimental data of 50's - 90's on elastic gamma-p scattering at photon energies below 150 MeV (10 experimental works) is performed in order to determine the electric (alpha_p) and magnetic (beta_p) polarizabilities of…