Time-reversal violation in light nuclei

Abstract

Time Reversal Violation (TRV) interactions between quarks which appear in Standard Model(SM) and beyond-SM theories can induce TRV components in the nucleon-nucleon potential. The effects of these components can be studied by measuring the electric dipole moment (EDM) of light nuclei. In this work we present a complete derivation of the TRV nucleon-nucleon and threenucleon potential up to next-to-next-to leading order (N2LO) in a chiral effective field theory (χEFT) framework. The TRV interaction is then used to evaluate the EDM of 2 H, 3 H and 3 He focusing in particular on the effects of the TRV three-body force and on the calculation of the theoretical errors. In case of a measurement of the EDM of these nuclei, the result of present work would permit to determine the values of the low energy constants and to identify the source of TRV.

Parity- and Time-Reversal-Violating Nuclear Forces

“…More precisely, the PVTV potential at NLO was used in combination with the N 2 LO PCTC potentials from Epelbaum et al [74]. Finally, in Gnech and Viviani [75], the EDMs of deuteron and trinucleons were studied using the χEFT PVTV potential up to N 2 LO along with the N 4 LO PCTC potential of Entem et al [18]. In this paper, it was also shown that the N 2 LO contribution to the PVTV 3N force generated by the three-pion interaction vanishes.…”

“…These can however always be absorbed into a shift ofḡ 0 and of the I = 0 NN operators discussed below. The NLO Lagrangian contains several two-pion two-nucleon PVTV interactions [65,68,69,75], but, for all CP-violating sources, they contribute to the two-and three-body PVTV potentials at N 3 LO and N 2 LO, respectively. We therefore ignore these couplings.…”

“…• N 2 LO two pion exchanges: triangle diagrams. The diagram depicted in panel (k) derives from subleading ππNN vertices in the PCTC Lagrangians [75,173], see Equation (13),…”

Trinucleon Electric Dipole Moments in Chiral EFT

“…Further terms of the Lagrangian involving derivatives would give rise to potential terms which can be reabsorbed in those generated by the Lagrangian given in Eq. (2.1) [17]. Moreover, the calculation of the EDM requires the inclusion of the electromagnetic currents,…”

“…Note the huge errors reported for the coefficients a ∆ which are due to the fact that the N2LO diagrams give a correction of ∼ 70%, quite far away from what predicted by chiral perturbation theory. This effect is mainly due to the large contribution of the diagrams in which the c 1 , c 2 , and c 3 LECs [17] of the PC potential appear. We found that the TRV 3-body forces enhanches of the order of ∼ 25% the pure two-body contribution at NLO.…”