Electromagnetic structure of few-nucleon ground states

Abstract

Abstract. Experimental form factors of the hydrogen and helium isotopes, extracted from an up-to-date global analysis of cross sections and polarization observables measured in elastic electron scattering from these systems, are compared to predictions obtained in three different theoretical approaches: the first is based on realistic interactions and currents, including relativistic corrections (labeled as the conventional approach); the second relies on a chiral effective field theory description of the strong and electromagnetic interactions in nuclei (labeled χEFT); the third utilizes a fully relativistic treatment of nuclear dynamics as implemented in the covariant spectator theory (labeled CST). For momentum transfers below Q 5 fm −1 there is satisfactory agreement between experimental data and theoretical results in all three approaches. However, at Q 5 fm −1 , particularly in the case of the deuteron, a relativistic treatment of the dynamics, as is done in the CST, is necessary. The experimental data on the deuteron A structure function extend to Q ≃ 12 fm −1 , and the close agreement between these data and the CST results suggests that, even in this extreme kinematical regime, there is no evidence for new effects coming from quark and gluon degrees of freedom at short distances.

Inclusive neutrino scattering off the deuteron at low energies in chiral effective field theory

“…This operator plays an important role in yielding predictions for the A = 2-4 charge form factors that are in excellent agreement with the experimental data at low and moderate values of the momentum transfer (q 1 GeV/c) [17,24]. The calculations in Ref.…”

“…[3] and [7] provide an excellent description of low-energy observables in the two-and three-nucleon systems (see Refs. [17,24] and references therein). In particular, the axial current in both approaches (χEFT and mesonexchange) is constrained to reproduce the tritium Gamow-Teller matrix element.…”

Local Nucleon-Nucleon and Three-Nucleon Interactions Within Chiral Effective Field Theory

“…In future, local chiral interactions will continue to serve as input for precise QMC methods to systematically study, for example, electroweak reactions, along the lines of Refs. [118,119,120,121,122,123,124] and infinite matter also at finite proton fractions.…”

Chiral electroweak currents in nuclei

“…Moving on to the EM charge operator, we show in Figs. 8 and 9 very recent calculations of the deuteron monopole and quadrupole form factors [80] and 4 He (charge) form factor [102]. There are no unknown LECs beyond g A , f π and the nucleon magnetic moments-the latter enter a relativistic correction, suppressed by Q 2 relative to the LO charge operator, i.e., the well-known spin-orbit term.…”