2,713 research outputs found
Using {\sc top-c} for Commodity Parallel Computing in Cosmic Ray Physics Simulations
{\sc top-c} (Task Oriented Parallel C) is a freely available package for
parallel computing. It is designed to be easy to learn and to have good
tolerance for the high latencies that are common in commodity networks of
computers. It has been successfully used in a wide range of examples, providing
linear speedup with the number of computers. A brief overview of {\sc top-c} is
provided, along with recent experience with cosmic ray physics simulations.Comment: Talk to be presented at the XI International Symposium on Very High
Energy Cosmic Ray Interaction
GEOS - An optical memory and control unit
GEOS optical memory and control unit for controlling operation of optical beacon - digital delayed command system with high accuracy real time cloc
Renormalization of Entanglement Entropy and the Gravitational Effective Action
The entanglement entropy associated with a spatial boundary in quantum field
theory is UV divergent, with the leading term proportional to the area of the
boundary. For a class of quantum states defined by a path integral, the
Callan-Wilczek formula gives a geometrical definition of the entanglement
entropy. We show that, for this class of quantum states, the entanglement
entropy is rendered UV-finite by precisely the counterterms required to cancel
the UV divergences in the gravitational effective action. In particular, the
leading contribution to the entanglement entropy is given by the renormalized
Bekenstein-Hawking formula, in accordance with a proposal of Susskind and
Uglum. We show that the subleading UV-divergent terms in the entanglement
entropy depend nontrivially on the quantum state. We compute new subleading
terms in the entanglement entropy and find agreement with the Wald entropy
formula for black hole spacetimes with bifurcate Killing horizons. We speculate
that the entanglement entropy of an arbitrary spatial boundary may be a
well-defined observable in quantum gravity.Comment: 26 pages, 2 figures. v2: minor corrections and clarification
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