Electric dipole moment of light nuclei in chiral effective field theory

CP-violating interactions at quark level generate CP-violating nuclear interactions and currents, which could be revealed by looking at the presence of a permanent nuclear electric dipole moment. Within the framework of chiral effective field theory, we discuss the derivation of the CP-violating nuclear potential up to next-to-next-to leading order (N2LO) and the preliminary results for the charge operator up to next-to leading order (NLO). Moreover, we introduce some renormalization argument which indicates that we need to promote the short-distance operator to the leading order (LO) in order to reabsorb the divergences generated by the one pion exchange. Finally, we present some selected numerical results for the electric dipole moments of 2H, 3He and 3H discussing the systematic errors introduced by the truncation of the chiral expansion.

NN interaction from chiral effective field theory and its application to neutron-antineutron oscillations

An N¯N potential is introduced which is derived within chiral effective field theory and fitted to up-to-date N¯N phase shifts and inelasticities, provided by a proper phase-shift analysis of available p¯p scattering data. As an application of this interaction neutron-antineutron oscillations in the deuteron are considered. In particular, results for the deuteron lifetime are presented, evaluated in terms of the free-space n−n¯ oscillation time, utilizing that N¯N potential together with an NN interaction likewise derived within chiral effective field theory.

$$A=4-7$$ $$\varXi $$ hypernuclei based on interactions from chiral effective field theory

We investigate the existence of bound $$\varXi $$ Ξ states in systems with $$A=4-7$$ A = 4 - 7 baryons using the Jacobi NCSM approach in combination with chiral NN and $$\varXi $$ Ξ N interactions. We find three shallow bound states for the NNN$$\varXi $$ Ξ system (with $$(J^\pi ,T)=(1^+,0)$$ ( J π , T ) = ( 1 + , 0 ) , $$(0^+,1)$$ ( 0 + , 1 ) and $$(1^+,1)$$ ( 1 + , 1 ) ) with quite similar binding energies. The $$^5_{\varXi }\mathrm {H}(\frac{1}{2}^+,\frac{1}{2})$$ Ξ 5 H ( 1 2 + , 1 2 ) and $$^7_{\varXi }\mathrm {H}(\frac{1}{2}^+,\frac{3}{2})$$ Ξ 7 H ( 1 2 + , 3 2 ) hypernuclei are also clearly bound with respect to the thresholds $$^4\mathrm {He} + \varXi $$ 4 He + Ξ and $$^6\mathrm {He} +\varXi $$ 6 He + Ξ , respectively. The binding of all these $$\varXi $$ Ξ systems is predominantly due to the attraction of the chiral $$\varXi $$ Ξ N potential in the $$^{33}S_1$$ 33 S 1 channel. A perturbative estimation suggests that the decay widths of all the observed states could be rather small.

Constraints on the $$\varLambda $$-Neutron Interaction from Charge Symmetry Breaking in the $$\mathbf {^4_\Lambda \mathrm{He}}$$ - $$\mathbf {^4_\Lambda \mathrm{H}}$$ Hypernuclei

We utilize the experimentally known difference of the $$\varLambda $$ Λ separation energies of the mirror hypernuclei $${^4_\varLambda \mathrm{He}}$$ Λ 4 He and $${^4_\varLambda \mathrm{H}}$$ Λ 4 H to constrain the $$\varLambda $$ Λ -neutron interaction. We include the leading charge-symmetry breaking (CSB) interaction into our hyperon-nucleon interaction derived within chiral effective field theory at next-to-leading order. In particular, we determine the strength of the two arising CSB contact terms by a fit to the differences of the separation energies of these hypernuclei in the $$0^+$$ 0 + and $$1^+$$ 1 + states, respectively. By construction, the resulting interaction describes all low energy hyperon-nucleon scattering data, the hypertriton and the CSB in $${^4_\varLambda \mathrm{He}}$$ Λ 4 He -$${^4_\varLambda \mathrm{H}}$$ Λ 4 H accurately. This allows us to provide first predictions for the $$\varLambda $$ Λ n scattering lengths, based solely on available hypernuclear data.