Triple Frontier: Change and Continuity on the Riverfront

Book Review Jacob Blanc and Frederico Freitas, eds. Big Water: The Making of the Borderlands between Brazil, Argentina, and Paraguay. (Tucson: University of Arizona Press, 2018).    Book Review Jacob Blanc and Frederico Freitas, eds. Big Water: The Making of the Borderlands between Brazil, Argentina, and Paraguay. (Tucson: University of Arizona Press, 2018).    Book Review Jacob Blanc and Frederico Freitas, eds. Big Water: The Making of the Borderlands between Brazil, Argentina, and Paraguay. (Tucson: University of Arizona Press, 2018).   &nbsp

There, In the Shadows: The Grace of Art in a "River Runs Through It"

"Any man-any artist, as Nietzsche or Cezanne would say- climbs the stairway in the tower of his perfection at the cost of a struggle with a deunde-not with an angel, as some have maintained, or with his muse. This fundamental distinction must be kept in mind if the root of a work of art is to be grasped." -Frederico Garcia Lorc

Renormalized QCD-inspired model for the pion and mesons

We apply the subtraction method to an effective QCD-inspired model, which includes the Coulomb plus a zero-range hyperfine interactions, to define a renormalized Hamiltonian for mesons. The spectrum of the renormalized Hamiltonian agrees with the one obtained with a smeared hyperfine interaction. The masses of the low-lying pseudo scalar and vector mesons are reasonably described within the model.Comment: 5 pages, 3 figures, 5 references. To be published in Nucl. Phys. B (Proc. Suppl.) Talk presented at the Workshop "Light-cone Physics: Particles and Strings" at ECT* in Trento, Sep 3-11, 200

Frederico el Pez

Grade Level(s): K-12Una actividad divertida para envolver a los estudiantes en el estudio del impacto de los humanos en los sistemas de ambiente (específicamente los ríos), y una gran actividad para extender la exploración de los estudiantes de una variedad de temas o asuntos.Adaptado de Karen Lind por Kate Ferguso

Pion-photon Transition Distribution Amplitudes in the Spectral Quark Model

The vector and axial pion-photon transition distribution amplitudes are analyzed in the Spectral Quark Model. We proceed by the evaluation of double distributions through the use of a manifestly covariant calculation based on the alpha representation of propagators. As a result polynomiality is incorporated and calculations become rather simple. Explicit formulas, holding at the low-energy quark-model scale, are obtained. The corresponding form factors for the anomalous decay pi0 -> gamma gamma* and the radiative pion decays are also evaluated and confronted with the data.Comment: 13 pages, 3 figure

Recursive renormalization of the singlet one-pion-exchange plus point-like interactions

The subtracted kernel approach is shown to be a powerful method to be implemented recursively in scattering equations with regular plus point-like interactions. The advantages of the method allows one to recursively renormalize the potentials, with higher derivatives of the Dirac-delta, improving previous results. The applicability of the method is verified in the calculation of the $^1S_0$ nucleon-nucleon phase-shifts, when considering a potential with one-pion-exchange plus a contact interaction and its derivatives. The $^1S_0$ renormalization parameters are fitted to the data. The method can in principle be extended to any derivative order of the contact interaction, to higher partial waves and to coupled channels.Comment: 12 pages, 3 figure

Hard Constituent Quarks and Electroweak Properties of Pseudoscalar Mesons

The high momentum components generated in the wave function of pseudoscalar mes* by the one-gluon-exchange interaction are investigated within a relativistic constituent quark model. Adopting the light-cone formalism, the sensitivity of the weak decay constant and the charge form factor to hard constituent quarks is illustrated.Comment: 11 pages and 5 figs. (to be requested), LaTeX, INFN-ISS 94/3. To appear in Physics Lett.

The nucleon-nucleon potential beyond the static approximation

We point out that, due to the use of static nucleon propagators in Heavy Baryon Chiral Perturbation Theory, the current calculations of the nucleon-nucleon potential miss certain contributions starting at two loops. These contributions give rise to contact interactions, which are both parametrically and numerically more important than the so called NNLO potentials. They show a peculiar dependence on the light quark masses, which should be taken into account when performing chiral extrapolations of lattice data. However, they do not appear to have an impact on phenomenology since they can be absorbed into redefinitions of unknown parameters which are usually fitted to data.Comment: 20 pages. Misprints corrected, explanations and references added. Journal version. Corrected misprints in formulas 30,31 and 32 in Journal versio

Nucleon and pion electromagnetic form factors in a light-front constituent quark model

Nucleon and pion electromagnetic form factors are evaluated in the spacelike region within a light-front constituent quark model, where eigenfunctions of a mass operator, reproducing a large set of hadron energy levels, are adopted and quark form factors are considered in the one-body current. The hadron form factors are sharply affected by the high momentum tail generated in the wave function by the one-gluon-exchange interaction. Useful information on the electromagnetic structure of light constituent quarks can be obtained from the comparison with nucleon and pion experimental data.Comment: 9 pages, latex, 4 figures available as separate .uu fil