arXiv subjects

M. Yoshimura

Publications and source records attributed to M. Yoshimura.

94 records · Page 6Linked to original sources

arXiv1994

Time Evolution of Pure Quantum State and Emergence of A Nearly Thermal State

Dynamical evolution of the quantum ground state (vacuum) is analyzed for time variant harmonic oscillators characterized by asymptotically constant frequency. The oscillatory density matrix in the asymptotic future is uniquely determined by a constant number of produced particles, independent of other details of transient behavior at intermediate times. Time average over one oscillation period yields a classical, in some cases even an almost thermal behavior. In an analytically soluble model the created particle number obeys the Planck distribution in a parameter limit. This suggests a new way of understanding the Gibbons-Hawking temperature in the de Sitter spacetime.

hep-th↗

arXiv1994

Moving Mirror Model of Hawking Evaporation

The moving mirror model is designed to extract essential features of the black hole formation and the subsequent Hawking radiation by neglecting complication due to a finite curvature. We extend this approach to dynamically treat back reaction against the mirror motion due to Hawking radiation. It is found that a unique model in two spacetime dimensions exists in which Hawking radiation completely stops and the end point of evaporation contains a disconnected remnant. When viewed from asymptotic observers at one side of the spacetime, quantum mechanical correlation is recovered in the end. Although the thermal stage accompanying short range correlation may last for an arbitrarily long period, at a much longer time scale a long tail of non-thermal correlation is clearly detected.

hep-th↗

arXiv1993

End Point of Hawking Evaporation -- Case of Integrable Model

Quantum back reaction due to $N$ massless fields may be worked out to a considerable detail in a variant of integrable dilaton gravity model in two dimensions. It is shown that there exists a critical mass of collapsing object of order $\hbar N \times$ (cosmological constant)$^{1/2}$, above which the end point of Hawking evaporation is two disconnected remnants of infinite extent, each separated by a mouth from the outside region. Deep inside the mouth there is a universal flux of radiation in all directions, in a form different from Hawking radiation. Below the critical mass no remnant is left behind, implying complete Hawking evaporation or even showing no sign of Hawking radiation. Existence of infinitely many static states of quantum nature is also demonstrated in this model.

hep-th↗

arXiv1993

Wormhole and Hawking Radiation

It is shown in a variant of two dimensional dilaton gravity theories that an arbitrary, localized massive source put in an initially regular spacetime gives rise to formation of the wormhole classically, without accompanying the curvature singularity. The semiclassical quantum correction under this wormhole spacetime yields Hawking radiation. It is expected, with the quantum back reaction added to the classical equation, that the information loss paradox may be resolved in this model.

hep-th↗