Johann Haidenbauer

Leading three-baryon forces from SU(3) chiral effective field theory

Leading three-baryon forces are derived within SU(3) chiral effective field theory. Three classes of irreducible diagrams contribute: three-baryon contact terms, one-meson exchange and two-meson exchange diagrams. We provide the minimal non-relativistic terms of the chiral Lagrangian, that contribute to these diagrams. SU(3) relations are given for the strangeness S=0 and -1 sectors. In the strangeness-zero sector we recover the well-known three-nucleon forces from chiral effective field theory. Explicit expressions for the lambda-nucleon-nucleon chiral potential in isospin space are presented.

Antinucleon-nucleon interaction in chiral effective field theory

A bstractResults of an exploratory study of the antinucleon-nucleon interaction within chiral effective field theory are reported. The antinucleon-nucleon potential is derived up to next-to-next-to-leading order, based on a modified Weinberg power counting, in close analogy to pertinent studies of the nucleon-nucleon interaction. The low-energy constants associated with the arising contact interactions are fixed by a fit to phase shifts and inelasticities provided by a recently published phase-shift analysis of antiproton-proton scattering data. The overall quality of the achieved description of the antinucleon-nucleon amplitudes is comparable to the one found in case of the nucleon-nucleon interaction at the same order. For most S-waves and several P-waves good agreement with the antinucleon-nucleon phase shifts and inelasticities is obtained up to laboratory energies of around 200 MeV.

Near-threshold

A systematic analysis of the near-threshold enhancement in the

\bar pp

bar pp

invariant mass spectrum measured in

invariant mass spectrum seen in the decay reactions

J/\psi

J/psi to x bar pp

and

and

\psi'

psi (3686) to x bar pp

Can one discriminate between meson-exchange and quark-gluon transition mechanisms in the pp→ΛΛ process?

(x = gamma,, omega,, rho,, pi,, eta)