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Luis A. Trevisan

Publications and source records attributed to Luis A. Trevisan.

8 recordsLinked to original sources
arXiv2023

Evidence of fractal structures in hadrons

This study focuses on the presence of (multi)fractal structures in confined hadronic matter through the momentum distributions of mesons produced in proton-proton collisions between 23 GeV and 63 GeV. The analysis demonstrates that the $q$-exponential behaviour of the particle momentum distributions is consistent with fractal characteristics, exhibiting fractal structures in confined hadronic matter with features similar to those observed in the deconfined quark-gluon plasma (QGP) regime. Furthermore, the systematic analysis of meson production in hadronic collisions at energies below 1 TeV suggests that specific fractal parameters are universal, independently of confinement or deconfinement, while others may be influenced by the quark content of the produced meson. These results pave the way for further research exploring the implications of fractal structures on various physical distributions and offer insights into the nature of the phase transition between confined and deconfined regimes.

hep-th↗
arXiv2009

Inflationary Lambda-Universe with Time Varying Fundamental Constants

Barrow, and Barrow and collaborators, have put forward theoretical models with variable fundamental constants including JBD theories. The experimental evidence for an accelerating Universe points out to a deceleration parameter approximately equal to -- 1. On the other hand, there is evidence for a time varying fine structure constant alpha . We have included the above results in a JBD cosmological model modified by J.D. Barrow by including a time varying speed of light, thus, finding an exponential inflationary phase with variables G, alpha and c . This means that the primordial value of alpha was exponentially larger than its present value. Planck`s time may not be then approximately 10 to the power - 43 s ; the same may happen to other Planck`s quantities. We found an exponentially time-decaying Cosmological term.

gr-qc↗
arXiv2009

Inflationary phase in Generalized Brans-Dicke theory

We find a solution for exponential inflation in a Brans-Dicke generalized model, where the coupling "constant " is variable. While in General Relativity the equation of state is p is equal to minus rho, here we find p proportional to rho, where the proportionality constant is smaller than -2/3. The negativity of cosmic pressure implies acceleration of the expansion, even with lambda < 0 >.

gr-qc↗
arXiv2002

On a time varying fine structure constant

By employing Dirac LNH, and a further generalization by Berman (GLNH), we estimate how should vary the total number of nucleons, the energy density, Newton Gravitational constant, the cosmological constant, the magnetic permeability and electric permitivity, of the Universe,in order to account for the experimentally observed time variation of the fine structure constant. As a bonus,we find an acceptable value for the deceleration parameter of the present Universe, compatible with the Supernovae observations.

gr-qc↗
arXiv2001

Possible Cosmological Implications of Time Varying Fine Structure Constant

We make use of Dirac LNH and results for a time varying fine structure constant in order to derive possible laws of variation for speed of light, the number of nucleons in the Universe, energy density and gravitational constant. By comparing with experimental bounds on G variation, we find that the deceleration paramenter of the present Universe is negative. This is coherent with recent Supernovae observations.

gr-qc↗