Papers by Luiz Antonio Barreiro
Journal of High Energy Physics, 2005
Proceedings of Fifth International Conference on Mathematical Methods in Physics — PoS(IC2006), 2007
The scalar and vector self-energies obtained through QCD sum rules are introduced in Quantum Hadr... more The scalar and vector self-energies obtained through QCD sum rules are introduced in Quantum Hadrodynamics (QHD) equations. The results indicate that the ratios of coupling constants to respective meson mass have a very small dependence on density. Then, an extended Brown-Rho scaling law is conjectured.
The scalar and vectorial self energies obtained through QCD sum rules are introduced in the Quant... more The scalar and vectorial self energies obtained through QCD sum rules are introduced in the Quantum Hadrodynamics (QHD) equations. This mixing between QHD and QCD can reproduce the nuclear matter properties and shows us that the ratio of coupling constant by the respective meson mass is approximately independent of the density. This last result permits to extend the Brown-Rho scaling law to include the coupling constants. Then a test is made with spherical nuclei.
We investigate the impact of new physics beyond the Standard Model to the s → dγ process, which i... more We investigate the impact of new physics beyond the Standard Model to the s → dγ process, which is responsible for the short-distance contribution to the radiative decay Ω − → Ξ − γ. We study three representative extensions of the Standard Model, namely a one-family technicolor model, a two Higgs doublet model and a model containing scalar leptoquarks. When constraints arising from the observed b → sγ transition and the upper limit on D 0 −D 0 mixing are taken into account, we find no significant contributions of new physics to the s → dγ process.
Physics Letters B, 1996
Binding energy differences of mirror nuclei for A=15, 17, 27, 29, 31, 33, 39 and 41 are calculate... more Binding energy differences of mirror nuclei for A=15, 17, 27, 29, 31, 33, 39 and 41 are calculated in the framework of relativistic deformed mean-field theory. The spatial components of the vector meson fields and the photon are fully taken into account in a self-consistent manner. The calculated binding energy differences are systematically smaller than the experimental values and lend support to the existency of the Okamoto-Nolen-Schiffer anomaly found decades ago in nonrelativistic calculations. For the majority of the nuclei studied, however, the results are such that the anomaly is significantly smaller than the one obtained within state-of-the-art nonrelativistic calculations.
Physics Letters B, 1995
We calculate within the framework of relativistic nuclear models the contribution of the ϱ0 - ω m... more We calculate within the framework of relativistic nuclear models the contribution of the ϱ0 - ω mixing interaction to the binding energy differences of the mirror nuclei in the neighborhood of A = 16 and A = 40. We use two relativistic models for the nuclear structure, one with scalar and vector Woods-Saxon potentials, and the Walecka model. The ϱ0
athena.biblioteca.unesp.br
QCD sum rules are used to calculate the contribution of short-distance singlequark transition s →... more QCD sum rules are used to calculate the contribution of short-distance singlequark transition s → dγ, to the amplitudes of the hyperon radiative decay, Ω − → Ξ − γ. We re-evaluate the Wilson coefficient of the effective operator responsible for this transition. We obtain a branching ratio which is comparable to the unitarity limit.
Journal of Physics Communications
This paper demonstrates the relationship between superstrings, Yang-Mills fields, and dual models... more This paper demonstrates the relationship between superstrings, Yang-Mills fields, and dual models. We discovered a novel and profound connection between these theories and their respective prescriptions for the calculation of scattering amplitudes, which directly demonstrates the duality between Field Theory and String Theory in a novel manner.
Journal of Applied Crystallography
The growth kinetics and the structure of organic/silica hybrids prepared from acid hydrolysis of ... more The growth kinetics and the structure of organic/silica hybrids prepared from acid hydrolysis of 1:1 molar mixtures of 3-glycidoxypropyltrimethoxysilane and tetraethoxysilane were studied by small-angle X-ray scattering (SAXS) at 315, 325 and 335 K. The evolution of the SAXS intensity is compatible with the growth of silica-rich domains by aggregation from a fixed number of primary particles. Two distinct growth regimes could be identified by analyzing the relation I(0) ∝ R g D between the intensity extrapolated to zero I(0), the radius of gyration R g of the aggregates and the exponent D, which gives information on the geometry and the mechanism of growth of the aggregates. An initial period was attributed to the growth of rod-like particles with approximately the same radius and variable length. At more advanced degrees of aggregation the process was controlled by the growth of larger aggregates with higher-order dimensionality. A narrow distribution of cylinder lengths given by t...
Physical review. E, 2016
We study some statistical properties for the behavior of the average squared velocity-hence the t... more We study some statistical properties for the behavior of the average squared velocity-hence the temperature-for an ensemble of classical particles moving in a billiard whose boundary is time dependent. We assume the collisions of the particles with the boundary of the billiard are inelastic, leading the average squared velocity to reach a steady-state dynamics for large enough time. The description of the stationary state is made by using two different approaches: (i) heat transfer motivated by the Fourier law and (ii) billiard dynamics using either numerical simulations and theoretical description.
Eprint Arxiv Nucl Th 0103053, Mar 21, 2001
The scalar and vector self-energies obtained through QCD sum rules are introduced in Quantum Hadr... more The scalar and vector self-energies obtained through QCD sum rules are introduced in Quantum Hadrodynamics (QHD) equations. The results indicate that the ratios of coupling constants to respective meson mass have a very small dependence on density. Then, an extended Brown-Rho scaling law is conjectured.
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Papers by Luiz Antonio Barreiro