Reactionp¯p→Λ¯Λ in the meson-exchange picture

Abstract

A study of the strangeness production process pp~AA at threshold and intermediate energies has been performed doing a full coupled-channel (pp, AA) calculation. The elastic part of the pp and AA interactions has been derived from a one-boson-exchange version of the Bonn NN potential and a corresponding extension to the hyperon-nucleon case whereas the annihilation part is taken into account by introducing suitable optical potentials. The transition interaction between pp and AA is based on Kand K*-meson exchange. A reasonably good description of empirical cross sections as well as polarization data is achieved. It is demonstrated that the results are quite sensitive even to short-range modifications of the channel interactions. We also compare our model with other approaches and suggest a new experiment which would be able to check the very different predictions of the meson-exchange and constituent quark model, respectively.PACS number(s): 25.43.+t, 13.75.Cs, 21.30. +j

Strong couplings and form factors of charmed mesons in holographic QCD

“…Using (25)- (26) in (57), (58) and (60) as well as the KK expansions (29), (33) and (34) we find that…”

“…If in addition to SU (4) flavor symmetry, heavy-quark spin symmetry is invoked, one has g ρDD = g ρD * D = g ρD * D * = g πD * D to leading order in the charm quark mass [27,28]. The coupling g ρππ is constrained by experimental data; the studies of the DN interaction in Refs [22][23][24] utilized such a SU (4) relation, taking g ρππ = 6.0, which is the value used in a large body of work conducted within the Jülich model [29,30] for light-flavor hadrons. This value of g ρππ implies through SU (4) symmetry g ρDD = 3, which is not very much different from predictions based on the vector meson dominance (VMD) model: g DDρ = 2.52−2.8 [31,32].…”

Charmed matter

“…Our strategy for studying the reactionpp →Λ − c Λ + c is similar to our recent work on the DN system [6,7], which was based on a hybrid model for the KN system that uses meson-baryon dynamics at long distances and quark-gluon dynamics at short distances [14,15]. Specifically, we build on the Jülich coupled channel approach [16,17] for the hyperon production reactionpp →ΛΛ, which takes into account rigorously the effects of the initial (pp) and final (ΛΛ) state interactions. In this model, the microscopic strangeness production process and the elastic parts of the interactions in the initial (pp) and final (ΛΛ) states are described by meson exchanges, while annihilation processes are accounted for by phenomenological optical potentials.…”

“…The basic ingredients of the original Jülich coupled channel approach [16,17] are as follows. The transition amplitude is obtained from the solution of a coupled-channel Lippmann-Schwinger equation, with a driving potential V which is a 2 × 2 matrix in channel space.…”

“…The interaction in the finalΛ − c Λ + c state is assumed to be the same as the one inΛΛ, i.e. the elastic part of the interaction is given by the isospin-zero σ and ω exchanges and the annihilation part is again parameterized by an optical potential which contains central, spin-orbit and tensor components [16]. Finally, the transition potential frompp toΛ − c Λ + c is given by t-channel D and D * exchanges and their explicit expressions are the same as for K and K * ; they are of the generic form…”