arXiv subjects

M. Gorchtein

Publications and source records attributed to M. Gorchtein.

21 records · Page 2Linked to original sources

arXiv2000

Dispersion relation formalism for virtual Compton scattering and the generalized polarizabilities of the nucleon

A dispersion relation formalism for the virtual Compton scattering (VCS) reaction on the proton is presented, which for the first time allows a dispersive evaluation of 4 generalized polarizabilities at a four-momentum transfer $Q^2 \leq$ 0.5 GeV$^2$. The dispersive integrals are calculated using a state-of-the-art pion photo- and electroproduction analysis. The dispersion formalism provides a new tool to analyze VCS experiments above pion threshold, thus increasing the sensitivity to the generalized polarizabilities of the nucleon.

hep-ph↗

arXiv1999

Compton scattering and polarizabilities of the nucleon

Fixed-$t$ subtracted dispersion relations are presented for Compton scattering off the nucleon at energies $E_γ\leq 500$ MeV, as a formalism to extract the nucleon polarizabilities from the data with a minimum of model dependence. The scalar polarizabilities difference $α- β$ and the backward spin polarizability $γ_π$ enter directly as fit parameters in this formalism.

hep-ph↗

arXiv1999

Fixed-t subtracted dispersion relations for Compton scattering off the nucleon

We present fixed-$t$ subtracted dispersion relations for Compton scattering off the nucleon at energies $E_γ\leq$ 500 MeV, as a formalism to extract the nucleon polarizabilities with a minimum of model dependence. The subtracted dispersion integrals are mainly saturated by $πN$ intermediate states in the $s$-channel $γN \to πN \to γN$ and $ππ$ intermediate states in the $t$-channel $γγ\to ππ\to N \bar N$. For the subprocess $γγ\to ππ$, we construct a unitarized amplitude and find a good description of the available data. We show results for Compton scattering using the subtracted dispersion relations and display the sensitivity on the scalar polarizability difference $α- β$ and the backward spin polarizability $γ_π$, which enter directly as fit parameters in the present formalism.

hep-ph↗