arXiv subjects

Claudio Nassif

Publications and source records attributed to Claudio Nassif.

13 recordsLinked to original sources

arXiv2017

Invariance of the fine structure constant with temperature of the expanding universe

Our goal is to interpret the energy equation from Doubly Special Relativity (DSR) of Magueijo-Smolin with an invariant Planck energy scale in order to obtain the speed of light with an explicit dependence on the background temperature of the expanding universe. We also investigate how other universal constants, including the fine structure constant, have varied since the early universe and, thus, how they have evoluted over the cosmological time related to the temperature of the expanding universe. For instance, we show that both the Planck constant and the electron charge were also too large in the early universe. However, we finally conclude that the fine structure constant has remained invariant with the age and temperature of the universe, which is in agreement with laboratory tests and some observational data.

physics.gen-ph↗

arXiv2017

Deformed Special Relativity with an energy barrier of a minimum speed

This research aims to introduce a new principle in the flat space-time geometry through the elimination of the classical idea of rest and by including a universal minimum limit of speed in the quantum world. This limit, unattainable by the particles, represents a preferred inertial reference frame associated with a universal background field that breaks Lorentz symmetry. There emerges a new relativistic dynamics where a minimum speed forms an inferior energy barrier. One of the interesting consequences of the existence of such a minimum speed is that it prevents the absolute zero temperature for an ultracold gas according to the third law of thermodynamics. So we will be able to provide a fundamental dynamical explanation for the third law through a connection between such a phenomenological law and the new relativistic dynamics with a minimum speed.

gr-qc↗

arXiv2016

Connection between Symmetrical Special Relativity and the Gravitational Bose Einstein Condensate of a Gravastar/Dark Energy Star: Are there singularities in spacetime like black holes?

We aim to search for a connection between an invariant minimum speed that breaks down the Lorentz symmetry and the Gravitational Bose Einstein Condensate (GBEC), which is the central core of a star of gravitating vacuum (Gravastar/Dark Energy Star) by introducing a cosmological constant into compact objects. This model was designed to circumvent the embarrassment generated by the paradoxes of a singularity as the final stage of a gravitational collapse, by introducing in place of the singularity of event horizon a spatial-temporal phase transition, a concept with which the causal structure of Symmetrical Special Relativity (SSR) helps us to elucidate by providing a quantum interpretation for GBEC and explaining the origin of anisotropy, which has been introduced in ad-hoc way before in the literature.

physics.gen-ph↗

arXiv2016

Deformed special relativity with an invariant minimum speed and its cosmological implications

The paper aims to introduce a new symmetry principle in the space-time geometry through the elimination of the classical idea of rest and by including a universal minimum limit of speed in the subatomic world. Such a limit, unattainable by particles, represents a preferred reference frame associated with a universal background field that breaks Lorentz symmetry. Thus the structure of space-time is extended due to the presence of a vacuum energy density, which leads to a negative pressure at cosmological scales. The tiny values of the cosmological constant and the vacuum energy density shall be successfully obtained, being in good agreement with current observational results.

gr-qc↗

arXiv2016

Unruh effect as foundation of universal gravitation within the cosmological scenario

We aim to build a simple model of a gas with temperature ($T$) in thermal equilibrium with a black-body that plays the role of the adiabatically expanding universe, so that each particle of such a gas mimics a kind of "particle" (quantum) of dark energy, which is inside a very small area of space so-called Planck area ($l_p^{2}$), that is the minimum area of the whole space-time represented by a huge spherical surface with area $4πr_u^2$, $r_u$ being the Hubble radius. So we should realize that such spherical surface is the surface of the black-body for representing the universe, whose temperature ($T$) is related to an acceleration ($a$) of a proof particle that experiences the own black-body radiation according to the Unruh effect. Thus, by using this model, we derive the law of universal gravitation, which leads us to understand the anti-gravity in the cosmological scenario and also estimate the tiny order of magnitude of the cosmological constant in agreement with the observational data.

gr-qc↗

arXiv2016

Asymptotic freedom and quarks confinement treated through Thompson's approach

In this work, we first use Thompson's renormalization group method to treat QCD-vacuum behavior close to the regime of asymptotic freedom. QCD-vacuum behaves effectively like a "paramagnetic system" of a classical theory in the sense that virtual color charges (gluons) emerge in it as spin effect of a paramagnetic material when a magnetic field aligns their microscopic magnetic dipoles. Making a classical analogy with the paramagnetism of Landau's theory,we are able to introduce a kind of Landau effective action without temperature and phase transition for simply representing QCD-vacuum behavior at higher energies as magnetization of a paramagnetic material in the presence of a magnetic field H. This reasoning allows us to use Thompson's heuristic approach in order to extract an "effective susceptibility" ($χ>0$) of QCD-vacuum. It depends on logarithmic of energy scale u to investigate hadronic matter. Consequently,we are able to get an "effective magnetic permeability" ($μ>1$) of such a "paramagnetic vacuum". As QCD-vacuum must obey Lorentz invariance,the attainment of $μ>1$ must simply require that the "effective electrical permissivity" is $ε<1$,in such a way that $με=1$ (c^2=1).This leads to the antiscreening effect, where the asymptotic freedom takes place. On the other hand, quarks cofinement, a subject which is not treatable by perturbative calculations, is worked by the present approach. We apply the method to study this subject in order to obtain the string constant, which is in agreement with the experiments.

hep-ph↗

arXiv2009

On the Electrodynamics of Moving Particles in Gravitational Fields

The present work aims to search for an implementation of new symmetries in the space-time in order to enable us to find a connection between electrodynamics and gravitation, from where quantum principles naturally emerge. To do that, first of all we build a heuristic model of the electromagnetic nature of the electron so that the influence of the gravitational field on the electrodynamics of such moving particle leads us essentially to an elimination of the classical idea of rest by introducing the idea of a universal minimum limit of speed ($V$). Such a lowest limit $V$, being unattainable by the particles, represents a fundamental and preferred reference frame connected to a universal background field (a vacuum energy) that breaks Lorentz symmetry. So there emerges a new principle of symmetry in the space-time at the subatomic level for very low energies close to the background frame ($v\approx V$), providing a fundamental understanding for the uncertainty principle.

physics.gen-ph↗

arXiv2007

A fundamental explanation for the tiny value of the cosmological constant

We will look for an implementation of new symmetries in the space-time structure and their cosmological implications. This search will allow us to find a unified vision for electrodynamics and gravitation. We will attempt to develop a heuristic model of the electromagnetic nature of the electron, so that the influence of the gravitational field on the electrodynamics at very large distances leads to a reformulation of our comprehension of the space- time structure at quantum level through the elimination of the classical idea of rest. This will lead us to a modification of the relativistic theory by introducing the idea about a universal minimum limit of speed in the space- time. Such a limit, unattainable by the particles, represents a preferred frame associated with a universal background field (a vacuum energy), enabling a fundamental understanding of the quantum uncertainties. The structure of space-time becomes extended due to such a vacuum energy density, which leads to a negative pressure at the cosmological scales as an anti-gravity, playing the role of the cosmological constant. The tiny values of the vacuum energy density and the cosmological constant will be successfully obtained, being in agreement with current observational results.

physics.gen-ph↗

arXiv2007

Foundations of a quantum gravity at large scales of length and its consequences for the dynamics of cosmological expansion

We attempt to find new symmetries in the space-time structure, leading to a modified gravitation at large length scales, which provides the foundations of a quantum gravity at very low energies. This search begins by considering a unified model for electrodynamics and gravitation, so that the influence of the gravitational field on the electrodynamics at very large distances leads to a reformulation of our understanding about space-time through the elimination of the classical idea of rest at quantum level. This leads us to a modification of the relativistic theory by introducing the idea of a universal minimum speed related to Planck minimum length. Such a speed, unattainable by the particles, represents a privileged inertial reference frame associated with a universal background field. The structure of space-time becomes extended due to such a vacuum energy density, which leads to a cosmological anti-gravity, playing the role of the cosmological constant. The tiny values of the vacuum energy density and the cosmological constant are successfully obtained, being in agreement with current observational results. We estimate the very high value of vacuum energy density at Planck length scale. After we find the critical radius of the universe, beyond which the accelerated expansion takes place. We show that such a critical radius is $R_{uc}=r_g/2$, where $r_g=2GM/c^2$, being $r_g$ the Shwarzschild radius of a sphere with a mass $M$ representing the total attractive mass contained in our universe. And finally we obtain the radius $R_{u0}=3r_g/4(>R_{uc})$ where we find the maximum rate of accelerated expansion. For $R_u>R_{u0}$, the rate of acceleration decreases to zero at the infinite, avoiding Big Rip.

gr-qc↗

arXiv2007

Thompson's renormalization group method applied to QCD at high energy scale

We use a renormalization group method to treat QCD-vacuum behavior specially closer to the regime of asymptotic freedom. QCD-vacuum behaves effectively like a "paramagnetic system" of a classical theory in the sense that virtual color charges (gluons) emerges in it as a spin effect of a paramagnetic material when a magnetic field aligns their microscopic magnetic dipoles. Due to that strong classical analogy with the paramagnetism of Landau's theory,we will be able to use a certain Landau effective action without temperature and phase transition for just representing QCD-vacuum behavior at higher energies as being magnetization of a paramagnetic material in the presence of a magnetic field $H$. This reasoning will allow us to apply Thompson's approach to such an action in order to extract an "effective susceptibility" ($χ>0$) of QCD-vacuum. It depends on logarithmic of energy scale $u$ to investigate hadronic matter. Consequently we are able to get an ``effective magnetic permeability" ($μ>1$) of such a "paramagnetic vacuum". Actually,as QCD-vacuum must obey Lorentz invariance,the attainment of $μ>1$ must simply require that the "effective electrical permissivity" is $ε<1$ in such a way that $με=1$ ($c^2=1$). This leads to the anti-screening effect where the asymptotic freedom takes place. We will also be able to extend our investigation to include both the diamagnetic fermionic properties of QED-vacuum (screening) and the paramagnetic bosonic properties of QCD-vacuum (anti-screening) into the same formalism by obtaining a $β$-function at 1 loop,where both the bosonic and fermionic contributions are considered.

hep-ph↗

arXiv2005

Quantum Electro and Chromodynamics treated by Thompson's heuristic approach

In this work we apply Thompson's method (of the dimensions and scales) to study some features of the Quantum Electro and Chromodynamics. This heuristic method can be considered as a simple and alternative way to the Renormalisation Group (R.G.) approach and when applied to QED-lagrangian is able to obtain in a first approximation both the running coupling constant behavior of alpha(mu) and the mass m(mu).The calculations are evaluated just at d_c=4, where d_c is the upper critical dimension of the problem, so that we obtain the logarithmic behavior both for the coupling alpha and the excess of mass Delta m on the energy scale mu. Although our results are well-known in the vast literature of field theories,it seems that one of the advantages of Thompson's method, beyond its simplicity is that it is able to extract directly from QED-lagrangian the physical (finite) behavior of alpha(mu) and m(mu), bypassing hard problems of divergences which normally appear in the conventional renormalisation schemes applied to field theories like QED. Quantum Chromodynamics (QCD) is also treated by the present method in order to obtain the quark condensate value. Besides this, the method is also able to evaluate the vacuum pressure at the boundary of the nucleon. This is done by assumming a step function behavior for the running coupling constant of the QCD, which fits nicely to some quantities related to the strong interaction evaluated through the MIT-bag model.

hep-ph↗

arXiv2000

Unified treatment of $A+B\to 0 $ and $A+A\to 0$ chemical reactions through Thompson's approach

In this work we propose an action to describe diffusion limited chemical reactions belonging to various classes of universality. This action is treated through Thompson's approach and can encompass both cases where we have segregation as in the $A+B\to 0$ reaction, as well the simplest one, namely the $A+A\to 0$ reaction .Our results for long time and long wavelength behaviors of the species concentrations and reaction rates agree with exact results of Peliti for $A+A\to 0$ reaction and rigorous results of Bramson and Lebowitz for $A+B\to 0$ reaction, with equal initial concentrations.The different classes of universality are reflected by the obtained upper critical dimensions varying continuously from $d_{c}=2$ in the first case to $d_{c}=4$ in the last one. Just at the upper critical dimensions we find universal logarithmic corrections to the mean field behavior.

hep-ph↗

arXiv2000

Thompson's Method applied to Quantum Electrodynamics (QED)

In this work we apply Thompson's method (of the dimensions) to study the quantum electrodynamics (QED). This method can be considered as a simple and alternative way to the renormalisation group (R.G) approach and when applied to QED lagrangian is able to obtain the running coupling constant behavior $α(μ)$, namely the dependence of $α$ on the energy scale. We also obtain the dependence of the mass on the energy scale. The calculations are evaluated just at $d_c=4$, where $d_c$ is the upper critical dimension of the problem, so that we obtain logarithmic behavior both for the coupling $α$ and the mass $m$ on the energy scale $μ$.

hep-th↗