arXiv subjects

G. Preparata

Publications and source records attributed to G. Preparata.

14 recordsLinked to original sources

arXiv2000

What hides at the center of the Sun ?

The Standard Solar Model (SSM) and its basic assumption of an equation of state of perfect gases for the plasmas of its interior is analyzed within the new theoretical framework of QED coherent states. We find that for $\frac{r}{r_{\odot}}\leq 0.3$ the SSM solution is unstable against collapse to a dense, {\it cold} coherent core and as a result a large suppression of $B^{8}$-neutrinos is obtained, apparently solving the long standing solar neutrino problem.

astro-ph↗

arXiv2000

Gas of wormholes: a possible ground state of Quantum Gravity

In order to gain insight into the possible Ground State of Quantized Einstein's Gravity, we have derived a variational calculation of the energy of the quantum gravitational field in an open space, as measured by an asymptotic observer living in an asymptotically flat space-time. We find that for Quantum Gravity (QG) it is energetically favourable to perform its quantum fluctuations not upon flat space-time but around a ``gas'' of wormholes of mass m_p, the Planck mass (m_p ~= 10^{19}GeV) and average distance l_p, the Planck length a_p(a_p ~= 10^{-33}cm). As a result, assuming such configuration to be a good approximation to the true Ground State of Quantum Gravity, space-time, the arena of physical reality, turns out to be well described by Wheeler's quantum foam and adequately modeled by a space-time lattice with lattice constant l_p, the Planck lattice.

gr-qc↗

arXiv1999

Glasses: a new view from QED coherence

Faced with the Kauzmann paradox, glasses have always been a puzzle for condensed matter theorists. We show that in a new picture of condensed matter, which takes into account the coherent interaction mechanisms of QED, glasses are nothing but liquids, whose non coherent fraction is highly depleted, very close to zero near T$_g$, the temperature of glass formation. Using the recently developed QED theory of liquid water, we are also able to give a successful account of the surprising finding of two low-temperature water amorphs and of their phase-transition.

cond-mat↗

arXiv1999

A Few Simple Observations on Pion-Condensation in Nuclei

We present a few simple observations on the occurrence of $π$-condensation in Nuclei, aimed at clarifying the nature of the $π$-condensation implied by the coherent nuclear $π$-N-$Δ$ interaction, proposed in 1990 to explain the puzzling emergence of the Shell-Model. We show that such condensation is totally unrelated to the one proposed by A. B. Migdal at the beginning of '70, which can easily be shown not to occur at the normal nucleon density $ρ_{N}\simeq$ 0.17 fm${}^{-3}$.

nucl-th↗

arXiv1998

A tale of two condensates: the odd "Bose - Einstein" condensation of atomic Hydrogen

The recent report of the observation of Bose-Einstein condensation in atomic Hydrogen, characterized by an "anomalous" density spectrum, is shown to be in agreement with the prediction of the existence of two condensates for temperatures lower than a well defined temperature (which for Hydrogen is $ 105~ μK $), based on the QED coherent interaction in a gas of ultracold atoms at a density $n > n_0 (n_0=(1/λ)^3, λ$ being the wave-length of the e.m. modes resonantly coupled to the Hydrogen atoms)

cond-mat.stat-mech↗

arXiv1998

Bose-Einstein vs. electrodynamic condensates: the question of order and coherence

The remarkable recent experiments on ensembles of magnetically trapped ultracold alkali atoms have demonstrated the transition to a highly ordered phase, that has been attributed to the process of quantum-mechanical condensation, predicted long ago (1924) by Bose and Einstein. After having presented our argument against the above attribution, we show that the known phenomenology, including a discrepancy of about one order of magnitude with the predictions of Bose- Einstein condensation, is in good agreement with the electromagnetic coherence induced on the alkali atoms by the long range electrodynamic interactions. We also predict that for temperatures lower than a well defined $T_{BEC}$, the state predicted by Bose and Einstein coexists with the new coherent electrodynamic state.

cond-mat.stat-mech↗

arXiv1998

Coherent QED, Giant Resonances and $(e^{+}e^{-})$ Pairs in High Energy Nucleus-Nucleus Collisions

We show that the coherent oscillations of the e.m. field induced by the collective quantum fluctuations of the nuclear matter field associated with the giant resonances, with frequencies $ω_{A}\simeq 78A^{-{1/3}}$ MeV, give rise to a significant $(e^+e^-)$ pair production in high energy Heavy Ion collisions. The approximate parameterless calculation of such yield is in good agreement with recent experimental observations.

nucl-th↗

arXiv1998

On the Ground State of Quantum Gravity

In order to gain insight into the possible Ground State of Quantized Einstein's Gravity, we have devised a variational calculation of the energy of the quantum gravitational field in an open space, as measured by an asymptotic observer living in an asymptotically flat space-time. We find that for Quantum Gravity (QG) it is energetically favourable to perform its quantum fluctuations not upon flat space-time but around a ``gas'' of wormholes, whose size is the Planck length $a_p$ ($a_p\simeq 10^{-33}$cm). As a result, assuming such configuration to be a good approximation to the true Ground State of Quantum Gravity, space-time, the arena of physical reality, turns out to be well described by Wheeler's Quantum Foam and adequately modeled by a space-time lattice with lattice constant $a_p$, the Planck lattice.

hep-th↗

arXiv1998

Sonoluminescence Unveiled ?

The widening phenomenology of Single Bubble Sonoluminescence (SBSL) is shown to be in good agreement with a new approach to condensed matter, based on the QED coherent interactions. Some remarkable properties of SBSL are shown to emerge from the electromagnetic release of part of the latent heat of the water's vapour-liquid phase transition occurring at the bubble surface after it becomes supersonic.

quant-ph↗

arXiv1998

Anomalies in H2O-D2O mixtures: Evidence for the Two-Fluid Structure of Water

Recent probing of H2O-D2O mixtures by various means (neutron deep-inelastic scattering, Raman absorption, electrical H+/D+ conductivity) revealed an unexpected dependence of the relevant physical quantities on the isotopic composition of the mixture. We show that these observation can find their physical rationale in the context of an approach to the physics of liquid water which takes into account the non-negligible interaction of the molecules with the electromagnetic field, from which a two-fluid micro- scopical picture of water naturally emerges.

cond-mat.stat-mech↗

arXiv1998

Coherent Electrodynamic Processes in Solid Molecular Hydrogen

The many experimental puzzles of solid hydrogen, that seem to defy the generally accepted view of condensed matter, are shown to be a rather straightforward consequence of a new approach to condensed matter physics, that takes into account the coherent electrodynamic processes, predicted by Quantum ElectroDynamics (QED) that have been so far overlooked. As a consequence, a revision of the present view, based on electrostatic forces only, is called for.

cond-mat.mtrl-sci↗

arXiv1997

On the Dielectric Instability of High-Pressure Hydrogen

We present a comment on a recent letter by B. Edwards, N.W. Ashcroft, Nature 388 (1997) 652, in which the dielectric instabilty of the phase III of the solid molecular hydrogen system is suggested on the basis of electrostatics.

cond-mat.stat-mech↗

arXiv1996

Diffractive Deep Inelastic Scattering: the hadronic nature of Quarks

In the framework of Anisotropic Chromo Dynamics, a non-perturbative model of QCD based on magnetic condensation in the vacuum, we develope a picture of the Pomeron. Within this model we are able to calculate the diffractive contribution to deep inelastic scattering in the small Bjorken x region, actually probed at Hera. We calculate the diffractive structure function of the proton and make the comparison with the experimental data of Zeus and H1 collaborations. Good agreement with the experimental data, both for the diffractive structure function $F_2^D$ and for the ''structure function'' of the Pomeron, is achieved.

hep-ph↗

arXiv1994

External magnetic fields in gauge theories

A general discussion is presented of the response of a gauge-field system to external magnetic fields, in the light of a theorem due to S. Elitzur. As a result a natural understanding emerges of some recent puzzling results from lattice MC simulations, as well as of the phenomenon of ``perfect diamagnetism'' of non-abelian gauge theories, discovered almost ten years ago.

hep-lat↗