* Astronomy

Title: Effective Field Theory
Authors: A. Pich

These lectures provide an introduction to the basic ideas and methods of Effective Field Theory, and a description of a few interesting phenomenological applications in particle physics. The main conceptual foundations are discussed in sections 2 and 3, which cover the momentum expansion and the most important issues associated with the renormalisation process. Section 4 presents an overview of Chiral Perturbation Theory, the low-energy realisation of Quantum Chromodynamics in the light quark sector. The Chiral Perturbation Theory framework is applied to weak transitions in section 5, where the physics of non-leptonic kaon decays is analysed. The so-called Heavy Quark Effective Theory is briefly discussed in section 6. The electroweak chiral Effective Field Theory is described in section 7, which contains a brief overview of the effective Lagrangian associated with the spontaneous electroweak symmetry breaking. Some summarising comments are finally given in section 8.

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In physics, an effective field theory is an approximate theory (usually a quantum field theory) that includes appropriate degrees of freedom to describe physical phenomena occurring at a chosen length scale, while ignoring substructure and degrees of freedom at shorter distances (or, equivalently, at higher energies).

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Light at quantum limit
A team of University of Toronto physicists has demonstrated a new technique to squeeze light to the fundamental quantum limit, a finding that has potential applications for high-precision measurement, next generation atomic clocks, novel quantum computing and our most fundamental understanding of the universe.
Krister Shalm, Rob Adamson and Professor Aephraim Steinberg of physics and Centre for Quantum Information and Quantum Control published their findings in the Jan. 1 issue of the prestigious international journal Nature.

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-- Edited by Blobrana at 22:46, 2009-01-06

A scientist has put forward the bizarre suggestion that there are two dimensions of time, not the one that we are all familiar with, and even proposed a way to test his heretical idea next year.
Time is no longer a simple line from the past to the future, in a four dimensional world consisting of three dimensions of space and one of time. Instead, the physicist envisages the passage of history as curves embedded in a six dimensions, with four of space and two of time.

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Title: Spacetime foam
Authors: A.A. Kirillov, E.P. Savelova
(Version v2)

Spacetime foam is analysed within the simplistic model of a set of scalar fields on a flat background. We suggest the formula for the path integral which allows to account for the all possible topologies of spacetime. We show that the proper path integral defines a cutoff for the field theory. The form of the cutoff is fixed by the field theory itself and has no free additional parameters. New features of the Feynman diagram technique are outlined and possible applications in quantum gravity are discussed.

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