The Effective Field Theory "without pions" at next-to-leading order is used to analyze universal bound state and scattering properties of the 3-and 4-nucleon system. Results of a variety of phase shift equivalent nuclear potentials are presented for bound state properties of 3 H and 4 He, and for the singlet S-wave 3 He-neutron scattering length a0( 3 He-n). The calculations are performed with the Refined Resonating Group Method and include a full treatment of the Coulomb interaction and the leading-order 3-nucleon interaction. The results compare favorably with data and values from AV18(+UIX) model calculations. A new correlation between a0( 3 He-n) and the 3 H binding energy is found. Furthermore, we confirm at next-to-leading order the correlations, already found at leadingorder, between the 3 H binding energy and the 3 H charge radius, and the Tjon line. With the 3 H binding energy as input, we get predictions of the Effective Field Theory "without pions" at next-toleading order for the root mean square charge radius of 3 H of (1.6±0.2) fm, for the 4 He binding energy of (28 ± 2.5) MeV, and for Re{a0( 3 He-n)} of (7.5 ± 0.6) fm. Including the Coulomb interaction, the splitting in binding energy between 3 H and 3 He is found to be (0.66 ± 0.03) MeV. The discrepancy to data of (0.10 ∓ 0.03) MeV is model independently attributed to higher order charge independence breaking interactions. We also demonstrate that different results for the same observable stem from higher order effects, and carefully assess that numerical uncertainties are negligible. Our results demonstrate the convergence and usefulness of the pion-less theory at next-to-leading order in the 4 He channel. We conclude that no 4-nucleon interaction is needed to renormalize the theory at next-to-leading order in the 4-nucleon sector.

Motivated by the fact that a polarized 3 He nucleus behaves as an 'effective' neutron target, we examine manifestations of neutron electromagnetic polarizabilities in elastic Compton scattering from the Helium-3 nucleus. We calculate both unpolarized and double-polarization observables using chiral perturbation theory to next-to-leading order (O(e 2 Q)) at energies, ω < ∼ m π , where m π is the pion mass. Our results show that the unpolarized differential cross section can be used to measure neutron electric and magnetic polarizabilities, while two double-polarization observables are sensitive to different linear combinations of the four neutron spin polarizabilities.

We use nucleon–nucleon phase shifts obtained from experimental data, together with the chiral expansion for the long-distance part of the NN interaction, to obtain information about the short-distance piece of the NN potential that is at work in the 1S0 channel. We find that if the scale R that defines the separation between ‘long-’ and ‘short-’ distance is chosen to be ≲1.8 fm then the energy dependence produced by short-distance dynamics is well approximated by a two-term polynomial for Tlab ⩽ 200 MeV. We also find that a quantitative description of NN dynamics is possible, at least in this channel, if one treats the long-distance parts of the chiral NN potential in perturbation theory. However, in order to achieve this we have to choose a separation scale R that is larger than 1.0 fm.

With the aim of investigating the resonance system of NO, equivalent width calculations have been made for the 213.575 nm, O1(31.5) line of the 1-0 band of y-system of NO for the photospheric HSRA model, and for the line 214.012 nm, O1(25.5) line of the same band system for Zwaan's (1974) sunspot model.Calculations show that 3,-band system would not show up in the photospheric spectrum whereas a sunspot model yields an equivalent width of 72 m~, suggesting that sunspots may provide relatively more favourable conditions for the detections of the resonance systems of some abundant molecules in the inaccessible ultraviolet region.

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