Spin Observables in the Two-Nucleon Capture and Dissociation Processes at Low Energies

Abstract

Spin observables in radiative neutron capture on a proton and its inverse process, photodisintegration of the deuteron are calculated using a pionless effective field theory with di-baryon fields. Good agreement with the results of existing standard nuclear physics approach is obtained at very low energies. As energy increases, however, the discrepancy between the effective field theory and the standard nuclear physics approach becomes substantial. We discuss the origin of the difference.

Spin-polarization observables of deuteron photodisintegration at low energies in pionless effective-field theory

“…Dibaryon fields which have the quantum numbers of two-nucleon systems in either scattering or bound states are introduced to faciliate the resummation of effective range effects to infinite order. The details of formalism up to next-to-leading order (NLO) for the photodisintegration of deuteron have been reported in [4,8,13]. The result of pionless EFT up to NLO in [4] shows discrepancy with the experimental data of P y [14], similar to the phenomenological nuclear force model calculations of [1,2], but the result is different from the potential model calculation with increasing photon energy.…”

Complete analysis of beam analyzing powers in d+γ⃗⃗n+p at near threshold energies

“…Over a period of more than six decades, a number of theoretical calculations based on potential models have been reported on n + p ⇌ d + γ. Several theoretical groups are working on this reaction using chiral effective field theory and several others using pionless effective field theory [51][52][53][54][55][56]. Induced polarization P y ¢ of the neutron in the deuteron photodisintegration using various potentials was calculated [57] and was found that the predictions are systematically larger than the measured P y ¢ values.…”

Neutrino-Deuteron Reactions at Solar Neutrino Energies in Pionless Effective Field Theory with Dibaryon Fields

“…These high-precision theories provide a unique opportunity in which we can probe the interactions of neutrino and deuteron with uncertainties due to strong interactions under control. In the publications during the last decade, we have been applying the pionless effective field theory with dibaryon fields (dEFT in short) [16,17] to the low-energy two-nucleon systems and phenomena such as electromagnetic (EM) form factors of the deuteron [18], synthesis of the deuteron at big bang energies [19], proton-proton scattering [20], their fusion [21], neutron-proton scattering [22], spin-dependent polarization [23][24][25], and hadronic parity violation in the radiative neutron-proton fusion or the dissociation of the deuteron [26][27][28][29][30]. We could verify that i) calculational complexity and difficulty are significantly reduced in dEFT compared to the calculations in phenomenological potential models or other EFTs, ii) convergence of the 1 EeV is an initialism of exa-electron volt, 10 18 eV.…”