The permutation group S_N and large Nc excited baryons

We study the excited baryon states for an arbitrary number of colors Nc from the perspective of the permutation group S_N of N objects. Classifying the transformation properties of states and quark-quark interaction operators under S_N allows a general analysis of the spin-flavor structure of the mass operator of these states, in terms of a few unknown constants parameterizing the unknown spatial structure. We explain how to perform the matching calculation of a general two-body quark-quark interaction onto the operators of the 1/Nc expansion. The inclusion of core and excited quark operators is shown to be necessary. Considering the case of the negative parity L=1 states transforming in the MS of S_N, we discuss the matching of the one-gluon and the Goldstone-boson exchange interactions.Comment: 38 pages. Final version to be published in Physical Review

Analytic solutions for nonlinear waves in coupled reacting systems

We analyze a system of reacting elements harmonically coupled to nearest neighbors in the continuum limit. An analytic solution is found for traveling waves. The procedure is used to find oscillatory as well as solitary waves. A comparison is made between exact solutions and solutions of the piecewise linearized system, showing how the linearization affects the amplitude and frequency of the solutions.Comment: 5 pages, 5 figures, RevTeX 4 styl

Poder y escritura : el Príncipe, la biblioteca y la dedicatoria (siglos XV-XVII)

Se muestra cómo la lectura y la escritura son actos sociales perfectamente normativizados en la cultura de la Edad Moderna. Se exponen los ejemplos de la biblioteca, una institución en la que tan importante como el material que conserva son las relaciones sociales que se establecen entorno a ella (así en las "bibliotecas reales" como en las particulares), y de la dedicatoria de libros, en la que los autores desarrollan un lenguage muy sutil que les permitía relacionarse de forma especial con el destinatario.Roger Chartier shows how reading and writing were perfectly normativized social acts in the culture of Modern Age. As a demonstration of his assertions, he sets two examples: the first concerning libraries, institutions where materials preserved there were as important as social relationship established round it (both in regal libraries and in private ones), the second about the dedications written in books, through which their authors developed a very subtle language that allowed them to set up a kind of especial relation with their final addressees

Positive parity pentaquark towers in large Nc QCD

We construct the complete set of positive parity pentaquarks, which correspond in the quark model to {\bar s} q^{Nc+1} states with one unit of orbital angular momentum L=1. In the large Nc limit they fall into the K=1/2 and K=3/2 irreps (towers) of the contracted SU(4)c symmetry. We derive predictions for the mass spectrum and the axial couplings of these states at leading order in 1/Nc. The strong decay width of the lowest-lying positive parity exotic state is of order O(1/Nc), such that this state is narrow in the large Nc limit. Replacing the antiquark with a heavy antiquark {\bar Q} q^{Nc+1}, the two towers become degenerate, split only by O(1/mQ) hyperfine interactions. We obtain predictions for the strong decay widths of heavy pentaquarks to ordinary baryons and heavy H(*)_{\bar Q} mesons at leading order in 1/Nc and 1/mQ.Comment: 21 pages, 2 figures, 5 table

Van Kampen's expansion approach in an opinion formation model

We analyze a simple opinion formation model consisting of two parties, A and B, and a group I, of undecided agents. We assume that the supporters of parties A and B do not interact among them, but only interact through the group I, and that there is a nonzero probability of a spontaneous change of opinion (A->I, B->I). From the master equation, and via van Kampen's Omega-expansion approach, we have obtained the "macroscopic" evolution equation, as well as the Fokker-Planck equation governing the fluctuations around the deterministic behavior. Within the same approach, we have also obtained information about the typical relaxation behavior of small perturbations.Comment: 17 pages, 6 figures, submited to Europ.Phys.J.

Multibaryons in the collective coordinate approach to the SU(3) Skyrme model

We obtain the rotational spectrum of strange multibaryon states by performing the SU(3) collective coordinate quantization of the static multi-Skyrmions. These background configurations are given in terms of rational maps, which are very good approximations and share the same symmetries as the exact solutions. Thus, the allowed quantum numbers in the spectra and the structure of the collective Hamiltonians we obtain are also valid in the exact case. We find that the predicted spectra are in overall agreement with those corresponding to the alternative bound state soliton model.Comment: 16 pages, 1 figur

Effects of Transport Memory and Nonlinear Damping in a Generalized Fisher's Equation

Memory effects in transport require, for their incorporation into reaction diffusion investigations, a generalization of traditional equations. The well-known Fisher's equation, which combines diffusion with a logistic nonlinearity, is generalized to include memory effects and traveling wave solutions of the equation are found. Comparison is made with alternate generalization procedures.Comment: 6 pages, 4 figures, RevTeX

Multibaryons with heavy flavors in the Skyrme model

We investigate the possible existence of multibaryons with heavy flavor quantum numbers using the bound state approach to the topological soliton model and the recently proposed approximation for multiskyrmion fields based on rational maps. We use an effective interaction lagrangian which consistently incorporates both chiral symmetry and the heavy quark symmetry including the corrections up to order 1/m_Q. The model predicts some narrow heavy flavored multibaryon states with baryon number four and seven.Comment: 8 pages, no figures, RevTe

A search for deeply bound kaonic nuclear states

We have measured proton and neutron energy spectra by stopping negative kaons on liquid helium4. Two distinct peak structures were found on both spectra, which were assigned to the formation of new kinds of strange stribaryons. In this paper, we summarize both results.Comment: 7 pages, 3 figures, HYP2003 conference proceeding

Negative Parity 70-plet Baryon Masses in the 1/Nc Expansion

The masses of the negative parity SU(6) 70-plet baryons are analyzed in the 1/Nc expansion to order 1/Nc and to first order in SU(3) breaking. At this level of precision there are twenty predictions. Among them there are the well known Gell-Mann Okubo and equal spacing relations, and four new relations involving SU(3) breaking splittings in different SU(3) multiplets. Although the breaking of SU(6) symmetry occurs at zeroth order in 1/Nc, it turns out to be small. The dominant source of the breaking is the hyperfine interaction which is of order 1/Nc. The spin-orbit interaction, of zeroth order in 1/Nc, is entirely fixed by the splitting between the singlet states Lambda(1405) and Lambda(1520), and the spin-orbit puzzle is solved by the presence of other zeroth order operators involving flavor exchange.Comment: 31 pages, 3 figure