25,959 research outputs found
Black Hole Solution of Quantum Gravity
We present a spherically symmetric and static exact solution of Quantum
Einstein Equations. This solution is asymptotically (for large ) identical
with the black hole solution on the anti--De Sitter background and, for some
range of values of the mass possesses two horizons. We investigate
thermodynamical properties of this solution.Comment: Plain Latex, 10 page
Solutions of Quantum Gravity Coupled to the Scalar Field
We consider the Wheeler-De Witt equation for canonical quantum gravity
coupled to massless scalar field. After regularizing and renormalizing this
equation, we find a one-parameter class of its solutions.Comment: 8 pages, LaTe
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Quantal Time Asymmetry: Mathematical Foundation And Physical Interpretation
Time in standard quantum mechanics extends from -infinity -infinity since according to causality, a quantum state phi(+) must be prepared first at a particular time t = t(0), before the probability vertical bar(psi(-)(t),phi+(t(0))vertical bar(2) for an observable psi(-) can be measured in it at t > t(0) (Feynman (1948)). In experiments on single Ba(+) ions, Dehmelt and others observed this finite preparation time as the ensemble of onset-times t(0)(1),t(0)(2), ..., t(0)(n) of dark periods. How the semigroup time evolution, t(0) equivalent to 0 < t < infinity with a beginning of time t(0), can suggest the parametrization of the resonance pole position of the Z-boson at S= s(R) as s(R) = (M(R) - i Gamma(R)/2)(2) in terms of a mass M(R) and a width Gamma(R) given by a lifetime tau = (h) over bar/Gamma(R), is the subject of this contribution dedicated to Augusto Garcia.Physic
Ballistic transport: A view from the quantum theory of motion
Ballistic transport of electrons through a quantum wire with a constriction
is studied in terms of Bohm's interpretation of quantum mechanics, in which the
concept of a particle orbit is permitted. The classical bouncing ball
trajectories, which justify the name ``ballistic transport'', are established
in the large wave number limit. The formation and the vital role of quantum
vortices is investigated.Comment: 14 pages, revtex, 4 postscript figure
Topological Aspects of the Non-adiabatic Berry Phase
The topology of the non-adiabatic parameter space bundle is discussed for
evolution of exact cyclic state vectors in Berry's original example of split
angular momentum eigenstates. It turns out that the change in topology occurs
at a critical frequency. The first Chern number that classifies these bundles
is proportional to angular momentum. The non-adiabatic principal bundle over
the parameter space is not well-defined at the critical frequency.Comment: 14 pages, Dep. of Physics, Uni. of Texas at Austin, Austin, Texas
78712, to appear in J. Physics
Topological Black Holes in Quantum Gravity
We derive the black hole solutions with horizons of non-trivial topology and
investigate their properties in the framework of an approach to quantum gravity
being an extension of Bohm's formulation of quantum mechanics. The solutions we
found tend asymptotically (for large ) to topological black holes. We also
analyze the thermodynamics of these space-times.Comment: 4pages, no figures, plain LaTe
Fast growing instabilities for non-parallel flows
Unstable modes growing when two plasma shells cross over a background plasma
at arbitrary angle , are investigated using a non-relativistic three
cold fluids model. Parallel flows with are slightly more unstable
than anti-parallel ones with . The case is as
unstable as the one, but the fastest growing modes are oblique.
While the most unstable wave vector varies with orientation, its growth rate
slightly evolves and there is no such thing as a stable configuration. A number
of exact results can be derived, especially for the case.Comment: 4 pages, 3 figures, to appear in Phys. Lett.
Quantum Adiabatic Approximation, Quantum Action, and Berry's Phase
An alternative interpretation of the quantum adiabatic approximation is
presented. This interpretation is based on the ideas originally advocated by
David Bohm in his quest for establishing a hidden variable alternative to
quantum mechanics. It indicates that the validity of the quantum adiabatic
approximation is a sufficient condition for the separability of the quantum
action function in the time variable. The implications of this interpretation
for Berry's adiabatic phase and its semi-classical limit are also discussed.Comment: uuencoded LaTeX file, 5 page
Statistics of weighted Poisson events and its applications
The statistics of the sum of random weights where the number of weights is
Poisson distributed has important applications in nuclear physics, particle
physics and astrophysics. Events are frequently weighted according to their
acceptance or relevance to a certain type of reaction. The sum is described by
the compound Poisson distribution (CPD) which is shortly reviewed. It is shown
that the CPD can be approximated by a scaled Poisson distribution (SPD). The
SPD is applied to parameter estimation in situations where the data are
distorted by resolution effects. It performs considerably better than the
normal approximation that is usually used. A special Poisson bootstrap
technique is presented which permits to derive confidence limits for
observations following the CPD.Comment: 14 pages, 2 figure
Improving Cost-effectiveness and Facilitating Participation of Developing Countries in International Emissions Trading
This paper discusses ways in which the next climate agreement a renegotiated Kyoto Protocol or a second-period agreement can be made more cost-effective. The discussion focuses on the design of international emissions trading to facilitate early participation by developing countries. Four aspects are highlighted: the design of compensation rules, the need to regulate the use of the CDM, the effect of allowing borrowing and the implications of a Commitment Period Reserve.Climate change policy; cost effectiveness; international emissions trading; Kyoto protocol; Clean Development Mechanism; Commitment Period Reserve; developing countries
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