arXiv subjects

F. Raciti

Publications and source records attributed to F. Raciti.

3 recordsLinked to original sources

arXiv1995

Micro--universes and ``strong black holes'': a purely geometric approach to elementary particles

We present here a panoramic view of our unified, bi--scale theory of gravitational and strong interactions [which is mathematically analogous to the last version of N.Rosen's bi--metric theory; and yields physical results similar to strong gravity's]. This theory, developed during the last 15 years, is purely geometrical in nature, adopting the methods of General Relativity for the description of hadron structure and strong interactions. In particular, hadrons are associated with `` strong black--holes'', from the external point of view, and with ``micro--universes'', from the internal point of view. Among the results herein presented, let us mention the derivation: (i) of confinement and (ii) asymptotic freedom for the hadron constituents; (iii) of the Yukawa behaviour for the strong potential at the static limit; (iv) of the strong coupling ``constant'', and (v) of mesonic mass spectra.

gr-qc↗

arXiv1995

More About Tunnelling Times, the Dwell Time, and the ``Hartman Effect"

In a recent review paper [{\em Phys. Reports} {\bf 214} (1992) 339] we proposed, within conventional quantum mechanics, new definitions for the sub-barrier tunnelling and reflection times. \ Aims of the present paper are: \ (i) presenting and analysing the results of various numerical calculations (based on our equations) on the penetration and return times $<τ_{\, \rm Pen}>$, $<τ_{\, \rm Ret}>$, during tunnelling {\em inside} a rectangular potential barrier, for various penetration depths $x_{\rm f}$; \ (ii) putting forth and discussing suitable definitions, besides of the mean values, also of the {\em variances} (or dispersions) ${\rm D} \, {τ_{\rm T}}$ and ${\rm D} \, {τ_{\, \rm R}}$ for the time durations of transmission and reflection processes; \ (iii) mentioning, moreover, that our definition $<τ_{\rm T}>$ for the average transmission time results to constitute an {\em improvement} of the ordinary dwell--time ${\ove τ}^{\rm Dw}$ formula: \ (iv) commenting, at last, on the basis of our {\em new} numerical results, upon some recent criticism by C.R.Leavens. \ \ We stress that our numerical evaluations {\em confirm} that our approach implied, and implies, the existence of the {\em Hartman effect}: an effect that in these days (due to the theoretical connections between tunnelling and evanescent--wave propagation) is receiving ---at Cologne, Berkeley, Florence and Vienna--- indirect, but quite interesting, experimental verifications. \ Eventually, we briefly analyze some other definitions of tunnelling times.

quant-ph↗

arXiv1995

Building scars for integrable systems

It is shown, by means of a simple specific example, that for integrable systems it is possible to build up approximate eigenfunctions, called {\it asymptotic eigenfunctions}, which are concentrated as much as one wants to a classical trajectory and have a lifetime as long as one wants. These states are directly related to the presence of shell structures in the quantal spectrum of the system. It is argued that the result can be extended to classically chaotic system, at least in the asymptotic regime.

quant-ph↗