302 research outputs found
How far does the analogy between causal horizon-induced thermalization with the standard heat bath situation go?
After a short presentation of KMS states and modular theory as the unifying
description of thermalizing systems we propose the absence of transverse vacuum
fluctuations in the holographic projections as the mechanism for an area
behavior (the transverse area) of localization entropy as opposed to the volume
dependence of ordinary heat bath entropy. Thermalization through causal
localization is not a property of QM, but results from the omnipresent vacuum
polarization in QFT and does not require a Gibbs type ensemble avaraging
(coupling to a heat bath).Comment: 10 pages, based on talk given at the 2002 Londrina Winter Schoo
Thermal behavior induced by vacuum polarization on causal horizons in comparison with the standard heat bath formalism
Modular theory of operator algebras and the associated KMS property are used
to obtain a unified description for the thermal aspects of the standard heat
bath situation and those caused by quantum vacuum fluctuations from
localization. An algebraic variant of lightfront holography reveals that the
vacuum polarization on wedge horizons is compressed into the lightray
direction. Their absence in the transverse direction is the prerequisite to an
area (generalized Bekenstein-) behavior of entropy-like measures which reveal
the loss of purity of the vacuum due to restrictions to wedges and their
horizons. Besides the well-known fact that localization-induced (generalized
Hawking-) temperature is fixed by the geometric aspects, this area behavior
(versus the standard volume dependence) constitutes the main difference between
localization-caused and standard thermal behavior.Comment: 15 page Latex, dedicated to A. A. Belavin on the occasion of his 60th
birthda
Confined Phase In The Real Time Formalism And The Fate Of The World Behind The Horizon
In the real time formulation of finite temperature field theories, one
introduces an additional set of fields (type-2 fields) associated to each field
in the original theory (type-1 field). In hep-th/0106112, in the context of the
AdS-CFT correspondence, Maldacena interpreted type-2 fields as living on a
boundary behind the black hole horizon. However, below the Hawking-Page
transition temperature, the thermodynamically preferred configuration is the
thermal AdS without a black hole, and hence there are no horizon and boundary
behind it. This means that when the dual gauge theory is in confined phase, the
type-2 fields cannot be associated with the degrees of freedom behind the black
hole horizon. I argue that in this case the role of the type-2 fields is to
make up bulk type-2 fields of classical closed string field theory on AdS at
finite temperature in the real time formalism.Comment: v2: cases divided into sections with more detailed explanations.
considerably enlarged with examples and a lot of figures. sec 4.1.2 for
general closed cut-out circuits and appendix A for a sample calculation newly
added. many minor corrections and clarifying comments. refs added. v3: refs
and related discussion added. 1+46 pages, 26 figures. published versio
Generalized constraints on quantum amplification
We derive quantum constraints on the minimal amount of noise added in linear
amplification involving input or output signals whose component operators do
not necessarily have c-number commutators, as is the case for fermion currents.
This is a generalization of constraints derived for the amplification of
bosonic fields whose components posses c-number commutators.Comment: 4 pages, 1 figure, submitted to Physical Review Letter
Quantum noise in ideal operational amplifiers
We consider a model of quantum measurement built on an ideal operational
amplifier operating in the limit of infinite gain, infinite input impedance and
null output impedance and with a feddback loop. We evaluate the intensity and
voltage noises which have to be added to the classical amplification equations
in order to fulfill the requirements of quantum mechanics. We give a
description of this measurement device as a quantum network scattering quantum
fluctuations from input to output ports.Comment: 4 pages, 2 figures, RevTe
First Order Semiclassical Thermal String in the AdS Spacetime
We formulate the finite temperature theory for the free thermal excitations
of the bosonic string in the anti-de Sitter (AdS) spacetime in the Thermo Field
Dynamics (TFD) approach. The spacetime metric is treated exactly while the
string and the thermal reservoir are semiclassically quantized at the first
order perturbation theory with respect to the dimensionless parameter \epsilon
= \a ' H^{-2}. In the conformal black-hole AdS background the
quantization is exact. The method can be extended to the arbitrary AdS
spacetime only in the first order perturbation. This approximation is taken in
the center of mass reference frame and it is justified by the fact that at the
first order the string dynamics is determined only by the interaction between
the {\em free} string oscillation modes and the {\em exact} background. The
first order thermal string is obtained by thermalization of the system
carried on by the TFD Bogoliubov operator. We determine the free thermal string
states and compute the local entropy and free energy in the center of mass
reference frame.Comment: Minor typos corrected. Two references added. LATeX file, 19 page
Space-time translational gauge identities in Abelian Yang-Mills gravity
We derive and calculate the space-time translational gauge identities in
quantum Yang-Mills gravity with a general class of gauge conditions involving
two arbitrary parameters. These identities of the Abelian group of translation
are a generalization of Ward-Takahasi-Fradkin identities and important for
general discussions of possible renormalization of Yang-Mills gravity with
translational gauge symmetry. The gauge identities in Yang-Mills gravity with a
general class of gauge conditions are substantiated by explicit calculations.Comment: 15 pages. To be published in The European Physical Journal - Plus
(2012
VERTICAL AND HORIZONTAL FORCES DURING CUTIING IN BASKETBALL UNDER DIFFERENT CONDITIONS
The purpose of this study is to evaluate ground reaction force responses in professional basketball athletes while executing this sport's typical cutting maneuver with and without ankle bracing: taping, aircast-type orthosis and basketball shoes. Eight athletes were dynamically analyzed during a basketball cutting maneuver with a force platform. We collected vertical and medial-lateral forces under these three conditions and analyzed force peaks of foot contact with the ground and propulsion and growth gradient for these forces. Results show that bracing did not significantly change Fymax1 and GCFymax1; significantly reduced Fymax2 and GG Fymax2. With respect to the medial-lateral component, there were no significant differences in relation to force magnitudes between the three study conditions. However, GG Fzmax1 was significantly greater for the sport shoe condition than for the taping condition. Bracing decreased ground reaction force at some instances, but increased in others
Gravitational Wave Spectrum in Inflation with Nonclassical States
The initial quantum state during inflation may evolve to a highly squeezed
quantum state due to the amplification of the time-dependent parameter,
, which may be the modified dispersion relation in
trans-Planckian physics. This squeezed quantum state is a nonclassical state
that has no counterpart in the classical theory. We have considered the
nonclassical states such as squeezed, squeezed coherent, and squeezed thermal
states, and calculated the power spectrum of the gravitational wave
perturbation when the mode leaves the horizon.Comment: 21 page
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