We show that the masses of the lowest-lying heavy baryons can be very well described in a pion mean-field approach. We consider a heavy baryon as a system consisting of the Nc − 1 light quarks that induce the pion mean field, and a heavy quark as a static color source under the influence of this mean field. In this approach we derive a number of model-independent relations and calculate the heavy baryon masses using those of the lowest-lying light baryons as input. The results are in remarkable agreement with the experimental data. In addition, the mass of the Ω * b baryon is predicted.PACS numbers: 12.39. Hg, 14.20.Lq, 14.20.Mr, 11.30.Qc Keywords: Masses of heavy baryons, Mean field with hedgehog symmetry, Flavor SU(3) symmetry breaking Heavy baryons and pion mean-field.-In a naive quark model a heavy baryon consists of a heavy quark and two light quarks. When the mass of the heavy quark m Q → ∞, the spin of the heavy quark S Q is conserved, which indicates that the spin of the light-quark degrees of freedom is also conserved:Because of this heavy-quark spin symmetry, the total spin of the light quarks can be considered as a good quantum number. This suggests that in the first approximation a heavy baryon can be viewed as a bound state of a heavy quark and a diquark. Thus, the flavor SU (3) f representations of the lowest-lying heavy baryons are: 3⊗3 = 3⊕6, of which the anti-triplet has S L = 0 and total S = 1/2 and the sextet has S L = 1 with S = 1/2 and S = 3/2. Since in the limit m Q → ∞ the heavy quark inside a heavy baryon can be regarded as a static color source, the dynamics of heavy baryons is governed by the light quarks.It is clear that the complete description of heavy baryons requires more involved treatment of light quarks. In the present Letter we propose to describe the dynamics of the light subsystem in a heavy baryon within a meanfield approach with a hedgehog [4] symmetry, motivated by Ref. [5]. Mean field approximations provide often a simple physical picture, so that they have been widely applied in a variety of fields in physics: Thomas-Fermi approximation in atomic physics, Ginzburg-Landau theory for superconductivity, Bethe method in statistical physics, shell models in nuclear physics, to name a few. In the seminal papers [6] Witten has argued that, to the leading order in 1/N c expansion, the lowest-lying light baryons can be also viewed as bound states of N c valence quarks in a mean field. In the limit of the large number of colors (N c ), the lowest-lying light baryons consist of N c valence quarks that produce an effective pion mean field, which arises from the vacuum polarization.The N c valence quarks are influenced by this pion mean field. The chiral-quark soliton model (χQSM) is constructed, based on this picture [7][8][9]. This mean field and a hedgehog symmetry allow one to derive the effective collective Hamiltonian that includes an explicit breaking of SU(3) f symmetry. The Hamiltonian involves the dynamical coefficients, which can be computed explicitly within the χQSM [10]...

We calculate magnetic transition moments in the chiral quark-soliton model, with explicit SU(3)symmetry breaking taken into account. The dynamical model parameters are fixed by experimental data for the magnetic moments of the baryon octet and from the recent measurements of Θ + mass. Known magnetic transition moments µ ΛΣ , µ N ∆ are reproduced and predictions for other octetdecuplet and octet-antidecuplet transitions are given. In particular µ ΣΣ * recently constrained by SELEX is shown to be below 0.82 µ N . The recent GRAAL data on η photoproduction off the nucleon are explained in terms of a new narrow antidecuplet neutron-like resonance.

The roles of light $\rho$ and $\omega$ vector mesons in the Skyrmion are investigated in a chiral Lagrangian derived from the hidden local symmetry (HLS) up to $O(p^4)$ including the homogeneous Wess-Zumino (hWZ) terms. We write a general "master formula" that allows us to determine the parameters of the HLS Lagrangian from a class of holographic QCD models valid at large $N_c$ and $\lambda$ ('t Hooft constant) limit by integrating out the infinite towers of vector and axial-vector mesons other than the lowest $\rho$ and $\omega$ mesons. Within this approach we find that the physical properties of the Skyrmion as the solitonic description of baryons are \textit{independent} of the HLS parameter $a$. Therefore the only parameters of the model are the pion decay constant and the vector meson mass. Once determined in the meson sector, we have a totally parameter-free theory that allows us to study unequivocally the role of light vector mesons in the Skyrmion structure. We find, as suggested by Sutcliffe, that inclusion of the $\rho$ meson reduces the soliton mass, which makes the Skyrmion come closer to the Bogomol'nyi-Prasad-Sommerfield (BPS) soliton, but the role of the $\omega$ meson is found to increase the soliton mass. In a stark contrast, the $\Delta$-$N$ mass difference, which is determined by the moment of inertia in adiabatic collective quantization of the Skyrmion, is increased by the $\rho$ vector meson, while it is reduced by the inclusion of the $\omega$ meson. All these observations show the importance of the $\omega$ meson in the properties of the nucleon and nuclear matter in the Skyrme model.Comment: REVTeX, 17 pages, 10 figures, to be published in Phys. Rev.

Abstract:We investigate the hyperon semileptonic decay constants, f 2 /f 1 , and g 1 /f 1 , within a general framework of a chiral soliton model. All relevant parameters for the SU(3) baryon wave functions were unambiguously determined by using the experimental data for the masses of the baryon octet and the decuplet. Using then the existing experimental data for the magnetic moments of the baryon octet and the decay constants of hyperon semileptonic decays, we are able to determine all the hyperon semileptonic decay constants f 2 /f 1 and g 1 /f 1 of the baryon octet unequivocally. In addition, we also present the results of the axial-vector transition constants from the baryon decuplet to the octet.

We investigate the mass spectra of the lowest-lying singly heavy baryons, based on the selfconsistent chiral quark-soliton model. We take into account the rotational 1/Nc and strange current quark mass (ms) corrections. Regarding ms as a small perturbation, we expand the effective chiral action to the second order with respect to ms. The mass spectra of heavy baryons are computed and compared with the experimental data. Fitting the classical masses of the heavy baryon to the center mass of each representation, we determine the masses of all the lowest-lying singly heavy baryons. We predict the mass of the Ω * b baryon to be 6081.9 MeV, when the second-order ms corrections are included.