Forward doubly-virtual Compton scattering off an unpolarized deuteron in pionless effective field theory

We calculate the forward unpolarised doubly-virtual Compton scattering (VVCS) off deuteron in framework of pionless effective field theory, up to next-to-next-to-next-to-leading order (N3LO) for longitudinal and next-to-leading (NLO) transverse amplitude. The charge elastic form factor deuteron, obtained from residue VVCS amplitude, is used extract value single unknown two-nucleon one-photon contact coupling that enters amplitude at N3LO. also study lowest spin-independent generalised polarisabilities deuteron. calculated provides a high-precision model-independent input future calculation two-photon-exchange correction Lamb shift muonic deuterium.