A.M. Green

The effect of the Δ(1236) in the two-nucleon problem and in neutron matter

Abstract A two nucleon interaction for the1S0 state is constructed by replacing the σ-meson in an OBEP by an inelastic process involving the Δ(1236). The values of the two free parameters introduced to fit δ( 1 s 0 ) are justified by more fundamental approaches. The binding energy of neutron matter is calculated, and it is shown there is a considerable repulsive contribution not present for an equivalent σ-meson interaction.

Three-body forces in nuclear matter

Abstract An earlier claim about the smallness of three-body effects in nuclear matter is examined in the light of a criticism. Our conclusion is that, whereas the lowest-order three-body effect is small, second-order effects are larger, with the net result of ≈ 2.5 MeV per particle additional binding at the saturation density. Although these results depend on the way one extrapolates off the pion mass shell, different ways which seem to us to be reasonable give roughly the same result.

Are there eta helium bound states

Using multiple scattering theory the scattering lengths of {eta} mesons on helium nuclei are calculated and checked against final state {eta} interactions from the {ital pd}{r_arrow}{eta}{sup 3}He and {ital dd}{r_arrow}{eta}{sup 4}He reactions. The existence of an {eta}{sup 4}He quasibound state is indicated.

The effect of the Delta (1236) on the imaginary component of nucleon-nucleon phase-shifts

A study is made, within the Delta -configuration approach, of several processes which could contribute to the imaginary components of nucleon-nucleon phase-shifts. However, as in earlier estimates with this model, the final results for low partial waves are far from the values suggested by phase-shift analyses. The imaginary components in high partial waves are calculated in the Born approximation and could be utilised in removing some of the ambiguities in phase-shift analyses at energies less than than 1 GeV. In addition, a new transition potential for generating Delta configurations is derived in such a way as to be more consistent with the two-pion exchange contribution of recent semi-theoretical nucleon-nucleon potentials.

On the energy levels in antiprotonic deuterium

Abstract The widths and level shifts of the 1S, 2P and 3D levels in antiprotonic deuterium are calculated using a separable NN potential based on the Dover-Richard scattering parameters.

Excited B mesons from the lattice

We determine the energies of the excited states of a heavy-light meson

P-wave meson production in p + p → d + π+

Q\bar{q}

The saturating effect of the Δ(1236) in nuclear matter

, with a static heavy quark and light quark with mass approximately that of the strange quark from both quenched lattices and with dynamical fermions. We are able to explore the energies of orbital excitations up to L=3, the spin-orbit splitting up to L=2 and the first radial excitation. These

pp̄ annihilation in an S-wave quark rearrangement model

b \bar{s}

Muon-capture and the ground-state wave function of 16O

mesons will be very narrow if their mass is less than 5775 MeV -- the