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Giovanni Amelino-Camelia

Publications and source records attributed to Giovanni Amelino-Camelia.

156 records · Page 9Linked to original sources
arXiv1999

Neutral Kaon System in Dense Matter and Heavy-Ion Collisions

Above a critical matter density the propagating modes of the neutral kaon system are essentially eigenstates of strangeness, but below it they are almost complete eigenstates of CP. We estimate the real and imaginary parts of the energies of these modes and their mixing at all densities up to nuclear matter density $2\times 10^{14}$ g/cm$^3$. In a heavy ion collision the strong interactions create eigenstates of strangeness, and these propagate adiabatically until the density has fallen to the critical value, whereupon the system undergoes a sudden transition to (near) eigenstates of CP. We estimate the critical density to be 20 g/cm$^3$, and that this density will be reached about $2\times 10^5$ fm/c after the end of the collision.

hep-ph↗
arXiv1999

Waves on Noncommutative Spacetime and Gamma-Ray Bursts

Quantum group Fourier transform methods are applied to the study of processes on noncommutative Minkowski spacetime $[x^i,t]=\imathλx^i$. A natural wave equation is derived and the associated phenomena of {\it in vacuo} dispersion are discussed. Assuming the deformation scale $λ$ is of the order of the Planck length one finds that the dispersion effects are large enough to be tested in experimental investigations of astrophysical phenomena such as gamma-ray bursts. We also outline a new approach to the construction of field theories on the noncommutative spacetime, with the noncommutativity equivalent under Fourier transform to non-Abelianness of the `addition law' for momentum in Feynman diagrams. We argue that CPT violation effects of the type testable using the sensitive neutral-kaon system are to be expected in such a theory.

hep-th↗
arXiv1999

Gravity-wave interferometers as probes of a low-energy effective quantum gravity

The interferometry-based experimental tests of quantum properties of space-time which the author sketched out in a recent short Letter [Nature 398 (1999) 216] are here discussed in self-contained fashion. Besides providing detailed derivations of the results already announced in the previous Letter, some new results are also derived; in particular, the analysis is extended to a larger class of scenarios for space-time fuzziness and an absolute bound on the measurability of the amplitude of a gravity wave is obtained. It is argued that these studies could be helpful for the search of a theory describing a first stage of partial unification of Gravity and Quantum Mechanics.

gr-qc↗
arXiv1999

Distance Measurement and $κ$-Deformed Propagation of Light and Heavy Probes

We investigate the implications for the measurability of distances of a covariant dimensionful ``$κ$'' deformation of D=4 relativistic symmetries, with quantum time coordinate and modified Heisenberg algebra. We show that the structure of the deformed mass-shell condition has significant implications for measurement procedures relying on light probes, whereas in the case of heavy probes the most sizeable effect is due to the nontrivial commutation relation between three-momenta and quantum time coordinate. We argue that these findings might indicate that $κ$-Poincaré symmetries capture some aspects of the physics of the Quantum-Gravity vacuum.

gr-qc↗
arXiv1998

An interferometric gravitational wave detector as a quantum-gravity apparatus

As a consequence of the extreme precision of the measurements it performs, an interferometric gravitational wave detector is a macroscopic apparatus for which quantum effects are not negligible. I observe that this property can be exploited to probe some aspects of the interplay between Quantum Mechanics and Gravity.

gr-qc↗
arXiv1998

T-duality for boundary-non-critical point-particle and string quantum mechanics

It is observed that some structures recently uncovered in the study of Calogero-Sutherland models and anyons are close analogs of well-known structures of boundary conformal field theory. These examples of ``boundary conformal quantum mechanics'', in spite of their apparent simplicity, have a rather reach structure, including some sort of T-duality, and could provide useful frameworks for testing general properties of boundary conformal theories. Of particular interest are the duality properties of anyons and Calogero-Sutherland particles in presence of boundary-violations of conformal invariance; these are here briefly analyzed leading to the conjecture of a general interconnection between (deformed) boundary conformal quantum mechanics, T-type duality, and (``exchange'' or ``exclusion'') exotic statistics. These results on the point-particle quantum-mechanics side are compared with recent results on the action of T-duality on open strings that satisfy conformal-invariance-violating boundary conditions. Moreover, it is observed that some of the special properties of anyon and Calogero-Sutherland quantum mechanics are also enjoyed by the M(atrix) quantum mechanics which has recently attracted considerable attention.

hep-th↗
arXiv1998

Could we observe the discreteness of Quantum-Gravity length and area operators ?

Several proposals for Quantum Gravity involve length and area operators with discrete eigenvalues. I show that the analyses of some simple procedures for the measurement of areas and lengths suggest that this discreteness characterizing the formalism might not be observable. I also discuss a possible relation with the so-called $κ$ deformations of Poincare' symmetries.

gr-qc↗
arXiv1998

Dimensionful deformations of Poincare' symmetries for a Quantum Gravity without ideal observers

Quantum Mechanics is revisited as the appropriate theoretical framework for the description of the outcome of experiments that rely on the use of classical devices. In particular, it is emphasized that the limitations on the measurability of (pairs of conjugate) observables encoded in the formalism of Quantum Mechanics reproduce faithfully the ``classical-device limit'' of the corresponding limitations encountered in (real or gedanken) experimental setups. It is then argued that devices cannot behave classically in Quantum Gravity, and that this might raise serious problems for the search of a class of experiments described by theories obtained by ``applying Quantum Mechanics to Gravity.'' It is also observed that using heuristic/intuitive arguments based on the absence of classical devices one is led to consider some candidate Quantum-Gravity phenomena involving dimensionful deformations of the Poincare' symmetries.

gr-qc↗
arXiv1998

On the area operators of the Husain-Kuchar-Rovelli model and Canonical/Loop Quantum Gravity

I investigate the relation between an operative definition of the area of a surface specified by matter fields and the area operators recently introduced in the canonical/loop approach to Quantum Gravity and in Rovelli's variant of the Husain-Kuchar Quantum-Gravity toy model. The results suggest that the discreteness of the spectra of the area operators might not be observable.

gr-qc↗
arXiv1997

kappa-Deformed Covariant Phase Space and Quantum-Gravity Uncertainty Relations

We describe the deformed covariant phase space corresponding to the so-called kappa-deformation of D=4 relativistic symmetries, with quantum ``time'' coordinate and Heisenberg algebra obtained according to the Heisenberg double construction. The associated modified uncertainty relations are analyzed, and in particular it is shown that these relations are consistent with independent estimates of quantum-gravity limitations on the measurability of space-time distances.

hep-th↗
arXiv1996

On the Three-Anyon Harmonics

The 3-anyon problem is studied using a set of variables recently proposed in an anyon gauge analysis by Mashkevich, Myrheim, Olaussen, and Rietman (MMOR). Boundary conditions to be satisfied by the wave functions in order to render the Hamiltonian self-adjoint are derived, and it is found that the boundary conditions adopted by MMOR are one of the ways to satisfy these general self-adjointness requirements. The possibility of scale-dependent boundary conditions is also investigated, in analogy with the corresponding analyses of the 2-anyon case. The structure of the known solutions of the 3-anyon in harmonic potential problem is discussed in terms of the MMOR variables. Within a series expansion in a boson gauge framework the problem of finding any anyon wavefunction is reduced to a (possibly infinite) set of algebraic equations, whose numerical analysis is proposed as an efficient way to study anyon physics.

hep-th↗