The Experts below are selected from a list of 37743 Experts worldwide ranked by ideXlab platform
E. Spallucci - One of the best experts on this subject based on the ideXlab platform.
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Bosonization in a two-dimensional Riemann-Cartan geometry
Il Nuovo Cimento B (1971-1996), 2007Co-Authors: G. Denardo, E. SpallucciAbstract:Si studia il funzionale del vuoto per un campo di Dirac in una geometria bidimensionale di Riemann-Cartan. La torsione è trattata come una variabile quantistica mentre la metrica è considerata come un campo classico. Il disaccoppiamento degli spinori dalla parte non-riemanniana della geometria introduce uno jacobiano chirale nel funzionale generante del vuoto. Si calcola questo determinante jacobiano funzionale mediante il metodo di Alvarez. Infine, si mostra che l'azione effettiva per la geometria di background è del tipo di Liouville e non conserva alcun ricordo del campo iniziale di torsione. Мы исследуем вакуумный функционал для поля Дирака в двумерной геометрии Римана-Картана. Кручение рассматривается как квантовая переменная, тогда как метрика рассматривается как классическое фоновое поле. Нарушение связи для спиноров, обусловленное неримановой частью геометрии, вводит киральный Якобиан в вакуумный производящий функционал. Мы вычисляем детерминант функционального Якобиана с помощью метода Альваренца. В заключение, мы показываем, что эффективное действие для геометрии фона представляет действие типа Лиувилля и не сохраняет какую-либо память о начальном поле кручения. We study the vacuum functional for a Dirac field in a two-dimensional Riemann-Cartan geometry. Torsion is treated as a Quantum Variable, while the metric is considered as a classical background field. Decoupling spinors from the non-Riemannian part of the geometry introduces a chiral Jacobian into the vacuum-generating functional. We compute this functional Jacobian determinant by means of the Alvarez method. Finally, we show that the effective action for the background geometry is of the Liouville type and does not preserve any memory of the initial torsion field.
Serge Reynaud - One of the best experts on this subject based on the ideXlab platform.
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Quantum Fluctuations of Mass for a Mirror in Vacuum
Physics Letters A, 1993Co-Authors: Marc-thierry Jaekel, Serge ReynaudAbstract:A mirror in vacuum is coupled to fluctuating Quantum fields. As a result, its energy-momentum and mass fluctuate. We compute the correlation spectra of force and mass fluctuations for a mirror at rest in vacuum (of a scalar field in a two-dimensional space-time). The obtained expressions agree with a mass correction equal to a vacuum energy stored by the mirror. We introduce a Lagrangian model which consistently describes a scalar field coupled to a scatterer, with inertial mass being a Quantum Variable.
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Quantum fluctuations of mass for a mirror in vacuum
Physics Letters A, 1993Co-Authors: Marc-thierry Jaekel, Serge ReynaudAbstract:Abstract A mirror in vacuum is coupled to fluctuating Quantum fields. As a result, its energy-momentum and mass fluctuate. We compute that correlation spectra of force and mass fluctuations for a mirror at rest in vacuum (of a scalar field in a two-dimensional space-time). The obtained expressions agree with a mass correction equal to a vacuum energy stored by the mirror. We introduce a Lagrangian model which consistently describes a scalar field coupled to a scatterer, with inertial mass being a Quantum Variable.
Alex H. Blin - One of the best experts on this subject based on the ideXlab platform.
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Cosmological Constant from Conformal Fluctuations of the Metric
arXiv: Astrophysics, 2001Co-Authors: Alex H. BlinAbstract:At the level of the Planck scale, the spacetime metric has to be considered a Quantum Variable. Conformal Quantum fluctuations of the metric tensor are studied here. They lead to an extra term in the Einstein equations which can be identified with a cosmological constant. Quantum fluctuations may therefore contribute to an accelerated expansion of the universe, in accordance with newer observational data.
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Cosmological Constant from
2001Co-Authors: Alex H. BlinAbstract:At the level of the Planck scale, the spacetime metric has to be considered a Quantum Variable. Conformal Quantum fluctuations of the metric tensor are studied here. They lead to an extra term in the Einstein equations which can be identified with a cosmological constant. Quantum fluctuations may therefore contribute to an accelerated expansion of the universe, in accordance with newer observational data.
J.j. Halliwell - One of the best experts on this subject based on the ideXlab platform.
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Coupling classical and Quantum Variables using continuous Quantum measurement theory
Physical Review Letters, 1998Co-Authors: Lajos Diósi, J.j. HalliwellAbstract:We propose a system of equations to describe the interaction of a quasiclassical Variable $X$ with a set of Quantum Variables $x$ that goes beyond the usual mean field approximation. The idea is to regard the Quantum system as continuously and imprecisely measured by the classical system. The effective equations of motion for the classical system therefore consist of treating the Quantum Variable $x$ as a stochastic c-number $\x (t) $ the probability distibution for which is given by the theory of continuous Quantum measurements. The resulting theory is similar to the usual mean field equations (in which $x$ is replaced by its Quantum expectation value) but with two differences: a noise term, and more importantly, the state of the Quantum subsystem evolves according to the stochastic non-linear Schrodinger equation of a continuously measured system. In the case in which the Quantum system starts out in a superposition of well-separated localized states, the classical system goes into a statistical mixture of trajectories, one trajectory for each individual localized state.
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Effective theories of coupled classical and Quantum Variables
Open Systems and Measurement in Relativistic Quantum Theory, 1Co-Authors: J.j. HalliwellAbstract:We address the issue of coupling Variables which are essentially classical to Variables that are Quantum. Two approaches are discussed. In the first, continuous Quantum measurement theory is used to construct a phenomenological description of the interaction of a quasiclassical Variable X with a Quantum Variable x, where the quasiclassical nature of X is assumed to have come about as a result of decoherence. The state of the Quantum subsystem evolves according to the stochastic non-linear Schrodinger equation of a continuously measured system, and the classical system couples to a stochastic c-number x(t) representing the imprecisely measured value of x. The theory gives intuitively sensible results even when the Quantum system starts out in a superposition of well-separated localized states. The second approach involves a derivation of an effective theory from the underlying Quantum theory of the combined quasiclassical-Quantum system, and uses the decoherent histories approach to Quantum theory.
G. Denardo - One of the best experts on this subject based on the ideXlab platform.
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Bosonization in a two-dimensional Riemann-Cartan geometry
Il Nuovo Cimento B (1971-1996), 2007Co-Authors: G. Denardo, E. SpallucciAbstract:Si studia il funzionale del vuoto per un campo di Dirac in una geometria bidimensionale di Riemann-Cartan. La torsione è trattata come una variabile quantistica mentre la metrica è considerata come un campo classico. Il disaccoppiamento degli spinori dalla parte non-riemanniana della geometria introduce uno jacobiano chirale nel funzionale generante del vuoto. Si calcola questo determinante jacobiano funzionale mediante il metodo di Alvarez. Infine, si mostra che l'azione effettiva per la geometria di background è del tipo di Liouville e non conserva alcun ricordo del campo iniziale di torsione. Мы исследуем вакуумный функционал для поля Дирака в двумерной геометрии Римана-Картана. Кручение рассматривается как квантовая переменная, тогда как метрика рассматривается как классическое фоновое поле. Нарушение связи для спиноров, обусловленное неримановой частью геометрии, вводит киральный Якобиан в вакуумный производящий функционал. Мы вычисляем детерминант функционального Якобиана с помощью метода Альваренца. В заключение, мы показываем, что эффективное действие для геометрии фона представляет действие типа Лиувилля и не сохраняет какую-либо память о начальном поле кручения. We study the vacuum functional for a Dirac field in a two-dimensional Riemann-Cartan geometry. Torsion is treated as a Quantum Variable, while the metric is considered as a classical background field. Decoupling spinors from the non-Riemannian part of the geometry introduces a chiral Jacobian into the vacuum-generating functional. We compute this functional Jacobian determinant by means of the Alvarez method. Finally, we show that the effective action for the background geometry is of the Liouville type and does not preserve any memory of the initial torsion field.