Black Hole Tunneling Entropy and the Spectrum of Gravity

The tunneling approach for entropy generation in quantum gravity is applied to black holes. The area entropy is recovered and shown to count only a tiny fraction of the black hole degeneracy. The latter stems from the extension of the wave function outside the barrier. In fact the semi-classical analysis leads to infinite degeneracy. Evaporating black holes leave then infinitely degenerate "planckons" remnants which can neither decay into, nor be formed from, ordinary matter in a finite time. Quantum gravity opens up at the Planck scale into an infinite Hilbert space which is expected to provide the ultraviolet cutoff required to render the theory finite in the sector of large scale physics.Comment: 26 pages + 3 figures, phyzzx macropackage, figures available from Author

Comment on ``Can Disorder Induce a Finite Thermal Conductivity in 1D Lattices?''

In a recent paper [Phys. Rev. Lett. 86, 63 (2001)], Li et al have reported that the nonequilibrium heat conducting steady state of a disordered harmonic chain is not unique. In this comment we point out that for a large class of stochastic heat baths the uniqueness of the steady state can be proved, and therefore the findings of Li et al could be either due to their use of deterministic heat baths or insufficient equilibration times in the simulations. We give a simple example where the uniquness of the steady state can be explicitly demonstrated.Comment: 1 page, 1 figure, accepted for publication in Phys. Rev. Let

A Numerical Experiment in DLCQ: Microcausality, Continuum Limit and all that

Issues related with microcausality violation and continuum limit in the context of (1+1) dimensional scalar field theory in discretized light-cone quantization (DLCQ) are addressed in parallel with discretized equal time quantization (DETQ) and the fact that Lorentz invariance and microcausality are restored if one can take the continuum limit properly is emphasized. In the free case, it is shown with numerical evidence that the continuum results can be reproduced from DLCQ results for the Pauli-Jordan function and the real part of Feynman propagator. The contributions coming from $k^+$ near zero region in these cases are found to be very small in contrast to the common belief that $k^+=0$ is an accumulation point. In the interacting case, aspects related to the continuum limit of DLCQ results in perturbation theory are discussed.Comment: Minor changes in the text, accepted for publication in Phys. Letts.

Black Hole Horizon Fluctuations

It is generally admitted that gravitational interactions become large at an invariant distance of order $1$ from the black hole horizon. We show that due to the ``atmosphere'' of high angular particles near the horizon strong gravitational interactions already occur at an invariant distance of the order of $\sqrt[3]{M}$. The implications of these results for the origin of black hole radiation, the meaning of black hole entropy and the information puzzle are discussed.Comment: Latex, 22 pages (minor corrections and precisions added

A hadron model with breaking of spatial homogeneity of vacuum

A possible breaking of spatial homogeneity of vacuum due to the interaction between quark and Bose-field is analyzed. It is shown that in this case quark can be in a localized state (like wave packet). Energetic conditions for such a spontaneous symmetry breaking are found in suggested model. Possible consequences of such symmetry breaking, in particular, the origin of deep inelastic processes and quark confinement phenomenon are discussed.Comment: 4 page

Heat Conduction in One-Dimensional chain of Hard Discs with Substrate Potential

Heat conduction of one-dimensional chain of equivalent rigid particles in the field of external on-site potential is considered. Zero diameters of the particles correspond to exactly integrable case with divergent heat conduction coefficient. By means of simple analytical model it is demonstrated that for any nonzero particle size the integrability is violated and the heat conduction coefficient converges. The result of the analytical computation is verified by means of numerical simulation in a plausible diapason of parameters and good agreement is observedComment: 14 pages, 7 figure

Second Stage String Fragmentation Model

A string model, advocated by Bowler, provides a physical and intuitive picture of heavy quark fragmentation. When supplemented by an ad hoc factor of (1-z), to suppress fragmentation near z=1, it supplies an excellent fit to the data. We extend Bowler's model by accounting for the further decay of the massive mesonic states produced by the initial string breaking. We find that each subsequent string break and cascade decay beyond the first, introduces a factor of (1-z). Furthermore we find that including a finite mass for the quarks, which pop out of the vacuum and split the string, forces the first string breaking to produce massive states requiring further decay. This sequence terminates at the second stage of fragmentation where only relatively "light" heavy meson systems are formed. Thus we naturally account for the phenomenologically required factor of (1-z). We also predict that the ratio of (primary) fragments-vector/(vector plus scalar) should be .61. Our second stage string fragmentation model provides an appealing picture of heavy quark fragmentation.Comment: 15 page