We investigate theDN interaction at low energies using a meson-exchange model supplemented with a short-distance contribution from one-gluon-exchange. The model is developed in close analogy to the meson-exchange KN interaction of the Jülich group utilizing SU(4) symmetry constraints. The main ingredients of the interaction are provided by vector meson (ρ, ω) exchange and higher-order box diagrams involvingD * N ,D∆, andD * ∆ intermediate states. The short range part is assumed to receive additional contributions from genuine quark-gluon processes. The predicted cross sections forDN for excess energies up to 150 MeV are of the same order of magnitude as those for KN but with average values of around 20 mb, roughly a factor two larger than for the latter system. It is found that the ω-exchange plays a very important role. Its interference pattern with the ρ-exchange, which is basically fixed by the assumed SU(4) symmetry, clearly determines the qualitative features of theDN interaction -very similiar to what happens also for the KN system. PACS. 14.40.Lb Charmed mesons -12.39.Pn Potential models -12.40.-y Other models for strong interactions -13.75.Jz Kaon-baryon interactions

Although asymptotic freedom is an essential feature of QCD, it is absent in effective chiral quark models like the Nambu-Jona-Lasinio and linear sigma models. In this work we advocate that asymptotic freedom plays a key role in the recently observed discrepancies between results of lattice QCD simulations and quark models regarding the behavior of the pseudocritical temperature T pc for chiral-symmetry restoration in the presence of a magnetic field B. We show that the lattice predictions that T pc decreases with B can be reproduced within the Nambu-Jona-Lasinio model if the coupling constant G of the model decreases with B and the temperature. Without aiming at numerical precision, we support our claim by considering a simple ansatz for G that mimics the asymptotic-freedom behavior of the QCD coupling constant 1/α s ∼ ln(eB/ 2 QCD ) for large values of B.

Chiral effective field theory is utilized for extrapolating results on the ΛcN interaction, obtained in lattice QCD at unphysical (large) quark masses, to the physical point. The pion-mass dependence of the components that constitute the ΛcN potential up to next-to-leading order (pion-exchange diagrams and four-baryon contact terms) is fixed by information from lattice QCD simulations. No recourse to SU(3) or SU(4) flavor symmetry is made. It is found that the results of the HAL QCD Collaboration for quark masses corresponding to mπ = 410-570 MeV imply a moderately attractive ΛcN interaction at mπ = 138 MeV with scattering lengths of a ≈ −1 fm for the 1 S0 as well as the 3 S1 partial waves. For such an interaction the existence of a charmed counterpart of the hypertriton seems unlikely but four-and/or five-baryons systems with a Λc baryon could be indeed bound.PACS. 14.20.Lq Charmed baryons (|C| > 0, B=0) -12.39.Fe Chiral Lagrangians -13.75.Ev Hyperonnucleon interactions -21.30.Fe Forces in hadronic systems and effective interactions

The q 2 dependence of the ρ − ω mixing amplitude is analyzed with the use of the QCD sum rules and the dispersion relation. Going off shell the mixing decreases, changes sign at q 2 ≃ 0.4m 2 ρ > 0 and is negative in the space like region. Implications of this result to the isospin breaking part of the nuclear force are discussed.