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Topic: Path integral formulation


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In the News (Thu 17 Dec 09)

  
  Path integral - Wikipedia, the free encyclopedia
In mathematics, a path integral (also known as a line integral) is an integral where the function to be integrated is evaluated along a path or curve.
In qualitative terms, a path integral in vector calculus can be thought of as a measure of the effect of a given vector field along a given curve.
However, path integrals in the sense of this article are important in quantum mechanics; for example, complex contour integration is often used in evaluating probability amplitudes in quantum scattering theory.
en.wikipedia.org /wiki/Path_integral   (680 words)

  
 Path integral formulation - Wikipedia, the free encyclopedia
The path integral formulation of quantum mechanics was developed in 1948 by Richard Feynman.
This formulation has proved crucial to the subsequent development of theoretical physics, since it provided the basis for the grand synthesis of the 1970's called the renormalization group which unified quantum field theory with statistical mechanics.
However, the path-integral formulation is also extremely important in direct application to quantum field theory, in which the "paths" or histories being considered are not the motions of a single particle, but the possible time evolutions of a field over all space.
en.wikipedia.org /wiki/Path_integral_formulation   (3038 words)

  
 Path Integral And Natural Selection - an Astronomy Net General Forum Message
In the case of the relationship of path integrals with natural selection, I think it is helpful to pick-up the double slit screen and throw it in the dumpster (or putting it in the equipment room where you can use it another day).
All of these paths face the whole of life, they face individual species, individual orders of life, etc. What the path integral does is provide a mathematical means of showing which path is more probable, which happens to be the path where the route is the most direct.
Well, the path integral is well-defined not just in terms of the possible paths and 'distances' of each path, it is also defined by the source and destination of all the collective paths.
www.astronomy.net /forums/general/messages/4497.shtml   (1209 words)

  
 Physics - Wikipedia, the free encyclopedia
During the 1920s Erwin Schrödinger, Werner Heisenberg, and Max Born were able to formulate a consistent picture of the chemical behavior of matter, a complete theory of the electronic structure of the atom, as a byproduct of the quantum theory.
Quantum field theory was formulated in order to extend quantum mechanics to be consistent with special relativity.
They formulated the theory of quantum electrodynamics, which describes the electromagnetic interaction, and successfully explained the Lamb shift.
en.wikipedia.org /wiki/Physics   (3898 words)

  
 Oxford University Press
The Feynman path integrals are becoming increasingly important in the applications of quantum mechanics and field theory.
Explicit and elementary path integral calculations of most of the quantum anomalies covered are given.
The conceptual basis of the path integral bosonization in two-dimensional theory, which may have applications to condensed matter theory, for example, is clarified.
www.oup.com /ca/isbn/0-19-852913-9   (375 words)

  
 Path integral formulation: Facts and details from Encyclopedia Topic   (Site not responding. Last check: 2007-10-21)
In calculus, the integral of a function is a generalization of area_(geometry)area, mass, volume, sum, and total....
Feynman showed that his formulation of quantum mechanics is equivalent to the canonical[Click link for more facts about this topic] approach to quantum mechanics.
(the path integral is taken to be fundamental and reality is viewed as a single indistinguishable "class" of paths which all share the same events.
www.absoluteastronomy.com /encyclopedia/p/pa/path_integral_formulation.htm   (5066 words)

  
 Solution of Coulomb Path Integral in Momentum Space
Thus, when transforming the time-sliced measure in the original path integral (3) to the time-sliced measure on the sphere in (9) which contains the effective action, the exponent is modified accordingly.
The path integral for a particle on the surface of a sphere was solved in [1].
The path integral with the action (8) in the exponent may thus be rewritten as a path integral with the gauge-invariant action (17) and an additional path integral
www.physik.fu-berlin.de /~kleinert/kleiner_re273/hatom.html   (1115 words)

  
 Path integral formulation of dissipative quantum dynamics
In this thesis the path integral formalism is applied to the calculation of the dynamics of dissipative quantum systems.
The path integral formalism in a combined phase-space and coherent-state representation is applied to the problem of curve-crossing dynamics.
Using the Feynman-Vernon influence-functional method the bath is eliminated whereas the non-Gaussian part of the path integral is treated using the perturbation theory in the small coordinate shift between potential energy surfaces.
archiv.tu-chemnitz.de /pub/2005/0050/index_en.html   (330 words)

  
 Edge: Stuart Kauffman & Lee Smolin Paper [page 2]   (Site not responding. Last check: 2007-10-21)
We propose an alternative formulation of quantum cosmological theories in which it is only necessary to predict the amplitudes for any given state to evolve to a finite number of possible successor states.
An example of such a theory is the recent path integral formulation of quantum gravity of Markopoulou and Smolin, but there are a wide class of theories of this type.
As an example we refer to recent work on the path integral for quantum gravity[causal], but the form of the theory we propose is more general, and may apply to a wide class of theories beyond quantum general relativity.
www.edge.org /3rd_culture/smolin/smolin_p2.html   (602 words)

  
 Action (physics): Encyclopedia topic   (Site not responding. Last check: 2007-10-21)
The path of an object is the one that yields a stationary value for a quantity called the action.
The action integral is a functional (functional: in mathematics, the term functional is applied to certain functions....
Path integral formulation (Path integral formulation: richard feynman developed the path integral formulation of quantum mechanics in 1948...
www.absoluteastronomy.com /reference/action_physics   (2152 words)

  
 OUP: Path Integrals in Quantum Mechanics: Zinn-Justin
Path integrals are mathematical objects that can be considered as generalizations to an infinite number of variables, represented by paths, of usual integrals.
Thus, path integrals lead to an intuitive understanding of physical quantities in the semi-classical limit, as well as simple calculations of such quantities.
Even though the formulation of quantum mechanics based on path integrals seems mathematically more complicated than the usual formulation based on partial differential equations, the path integral formulation is well adapted to systems with many degrees of freedom, where a formalism of Schrödinger type is much less useful.
www.oup.co.uk /isbn/0-19-856674-3   (406 words)

  
 Functional integration -   (Site not responding. Last check: 2007-10-21)
Physicists often refer informally to functional integrals over spaces of paths (or field configurations) as path integrals, which are different from path integrals in the usual sense.
Functional integration techniques in physics were pioneered by Richard Feynman, who successfully applied his "path integral formulation" to problems in quantum mechanics and quantum field theory, as well as classical and quantum statistical mechanics.
Functional integrals over manifolds are sometimes approximated by a lattice, but there is no guarantee this will give a good approximation or even converge.
psychcentral.com /psypsych/Functional_integral   (947 words)

  
 Amazon.com: Quantum Mechanics and Path Integrals: Books: Richard P. Feynman,A. R. Hibbs   (Site not responding. Last check: 2007-10-21)
The path integral formulation was also later used by other researchers to arrive at a semi-classical approximation to the three body problem, a nonintegrable and even chaotic classical system (nonintegrable classical systems cannot be solved by the standard method of finding a complete set of commuting constants of the motion).
The functional integral formulation of Brownian motion was formulated earlier by Norbert Wiener.
An analogous formulation of quantum theory was arrived at independently by Feynman, who took seriously a conjecture by Dirac about the meaning of the exponential of the classical action as a probability amplitude.
www.amazon.com /exec/obidos/tg/detail/-/0070206503?v=glance   (1383 words)

  
 Citebase - Spin-Statistics Theorem in Path Integral Formulation
The path integral for space-time noncommutative theory is formulated by means of Schwinger's action principle which is based on the equations of motion and a suitable ansatz of asymptotic conditions.
The path integral on the basis of Schwinger's action principle and the Bjorken-Johnson-Low prescription, which helps to recover the canonical structure from the results of the path integral, are used as the main...
We formulate a general convergence theorem for the noncommutative Feynman graphs in topological terms and prove it for some classes of diagrams in the scalar field theories.
citebase.eprints.org /cgi-bin/citations?id=oai:arXiv.org:hep-th/0107076   (1102 words)

  
 CMS/CAIMS Summer 2004 Meeting
A path integral formulation for pricing generally exotic derivative securities is presented.
We show how the known models fit into a classification scheme for diffusion processes for which generating functions for stochastic integrals and transition probability densities can be evaluated as integrals of hypergeometric functions against the spectral measure for certain self-adjoint operators.
By rearranging variables in path integral the increment of the process can be assigned to the first sampling coordinates.
www.cms.math.ca /Reunions/ete04/abs/fm.e   (909 words)

  
 The Quantum Pontiff » Wick Rotation
In the path integral formulation of quantum theory, we rewrite this as the path integral \int dq exp(i S(q)) where this integration is performed over all paths q and S(q) is the action (\int_0^t L(q,dot{q}) dt).
What has always astounded me is that often times we can calculate this path integral by performing a Wick rotation: we substitute -it for t in the path integral and thus we obtain a path integral with terms which don’t oscillate wildly.
So our hidden variables are not paths from minus infinity to plus infinity, but instead are now spacetime “loops” which go from minus infinity to plus infinity and then back to minus infinity.
dabacon.org /pontiff/index.php?p=714   (577 words)

  
 Quantum Mechanics and Path Integrals
The path integral formulation of quantum mechanics developed by Richard Feynman uses the so-called time-slicing technique.
K(b,a) is the sum of all amplitude φ[x(t)] for each path x(t).
Calculate the action of the path of a free particle in one dimension.
quantummechanics.blogspot.com   (438 words)

  
 [No title]   (Site not responding. Last check: 2007-10-21)
Title : Loop and Path Space Analysis Abstract : 9971036 Driver This research is primarily devoted to the study of the geometric analysis associated to heat kernel and Wiener measures on path and loop spaces of Riemannian manifolds.
It is hoped that these approximations will lead to: 1) a rigorous interpretation of the heuristic path integral proofs of the Atiyah--Singer index theorem, 2) construction of Brownian motions on path and loop spaces, 3) construction of non-trivial harmonic differential forms on loop groups, and 4) construction of Dirac operators on loop spaces.
This index theorem is arguably one of the most striking mathematical developments of this century and it has had far reaching implications in both mathematics and in physics.
www.cs.utexas.edu /users/yguan/NSFAbstracts/Abstracts/MPS/DMS.MPS.a9971036.txt   (236 words)

  
 Functional integration: Encyclopedia topic   (Site not responding. Last check: 2007-10-21)
Functional integration techniques in physics were pioneered by Richard Feynman (Richard Feynman: United States physicist who contributed to the theory of the interaction of photons and electrons (1918-1988)), who successfully applied his "path integral formulation (path integral formulation: richard feynman developed the path integral formulation of quantum mechanics in 1948...
Functional integrals over manifolds are sometimes approximated by a lattice (lattice: Framework consisting of an ornamental design made of strips of wood or metal), but there is no guarantee this will give a good approximation or even converge (converge: more facts about this subject).
For the use of functional integrals in quantum field theory, see path integral formulation (path integral formulation: richard feynman developed the path integral formulation of quantum mechanics in 1948...
www.absoluteastronomy.com /reference/functional_integration   (1123 words)

  
 Pharsea : Cause and Effort
In brief, this integral formulation of mechanics states that: if it is known that a particle (or more generally a system: a set of particles) starts at a place x
An infinite sum of path integrals is not an attractive proposition.
The path taken is such that small variations in that path have no effect on the phase factor.
pharsea.freewebsitehosting.com /CauseAndEffort.html   (6704 words)

  
 UofO Physics Graduate Student Seminar Schedule   (Site not responding. Last check: 2007-10-21)
The Feynman Path Integral formulation of quantum mechanics is much more elegant and intuitive than the usual operator formulation, and the Young double slit interference experiment provides a neat starting point.
Armed with little more than intuition and the classical principle of least action, we will construct the path integral formulation of quantum mechanics essentially from scratch.
Then, by deriving Schrodinger's equation, we will connect path integrals to the ordinary formulation of quantum mechanics which everyone is more accustomed to.
darkwing.uoregon.edu /~rrahkola/physics/gradsem/sem-schedule.html   (829 words)

  
 Finite Temperature Path Integral Method   (Site not responding. Last check: 2007-10-21)
It was shown that in a Path Integral Formulation fermionic density matrix can be expressed via an integration over a novel representation of the universal temperature dependent functional.
While several representations for the universal functional have already been developed, they are usually presented in a form inconvenient for computer calculations.
In this brief report we discuss a new representation for the universal functional in terms of the Hankel functions which is advantageous for computational applications.
ab-initio.mit.edu /atoms/path-integral.html   (114 words)

  
 CEF 1997: Option Pricing in a Path Integral Framework Using Fourier-Hermite Series Expansions   (Site not responding. Last check: 2007-10-21)
In this paper we review the path integral techniques (Dash 1988, Eydeland 1994, Chiarella and El-Hassan 1996), traditionally applied in statistical physics, and the applicability of such techniques to problems in mathematical finance.
In particular, we evaluate equity options, both European and American, in a path integral framework by employing expansions in Fourier-Hermite series, We also apply the path integral technique to evaluating bond options under various term structure models.
The computational efficiency, convergence rate and errors of the Fourier-Hermite series expansions on the path integral formulation are analyzed.
bucky.stanford.edu /cef97/abstracts/chiarella3.html   (150 words)

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