245 research outputs found
The vacuum state functional of interacting string field theory
We show that the vacuum state functional for both open and closed string
field theories can be constructed from the vacuum expectation values it must
generate. The method also applies to quantum field theory and as an application
we give a diagrammatic description of the equivalance between Schrodinger and
covariant repreresentations of field theory.Comment: 15 pages, 35 .eps figure
Radiation reaction in strong field QED
We derive radiation reaction from QED in a strong background field. We
identify, in general, the diagrams and processes contributing to recoil effects
in the average momentum of a scattered electron, using perturbation theory in
the Furry picture: we work to lowest nontrivial order in the electromagnetic
coupling alpha. For the explicit example of scattering in a plane wave
background, we compare QED with classical electrodynamics in the limit h-bar
goes to zero, finding agreement with the Lorentz-Abraham-Dirac and
Landau-Lifshitz equations, and with Larmor's formula. The first quantum
corrections are also presented.Comment: Version2: 7 pages, 2 figures. Discussion of related results and
applications extended, references added. Matches version to appear in
Phys.Lett.
Radiation reaction from QED: lightfront perturbation theory in a plane wave background
We derive dynamical, real time radiation reaction effects from lightfront
QED. Combining the Hamiltonian formalism with a plane wave background field,
the calculation is performed in the Furry picture for which the background is
treated exactly while interactions between quantum fields are treated in
perturbation theory as normal. We work to a fixed order in perturbation theory,
but no other approximation is made. The literature contains many proposals for
the correct classical equation describing a radiating particle; we take the
classical limit of our results and identify which equations are consistent with
QED.Comment: 33 pages, 5 pdf figures. Version 3: corrected typographical mistakes
and presentation issues in equations 4.10--4.14 and accompanying discussion.
Results and conclusions unaffected and unchange
Corrections to Laser Electron Thomson Scattering
We discuss classical and quantum corrections to Thomson scattering between an
electron and a laser. For radiation reaction, nonlinear, and quantum effects we
identify characteristic dimensionless parameters in terms of which we determine
the leading order correction terms.Comment: 5 pages, 1 figure; updated version of contribution to 2012 Annual
Report, Central Laser Facility (CLF), Rutherford-Appleton Laboratory, U
Stability, creation and annihilation of charges in gauge theories
We show how to construct physical, minimal energy states for systems of
static and moving charges. These states are manifestly gauge invariant. For
charge-anticharge systems we also construct states in which the gauge fields
are restricted to a finite volume around the location of the matter fields.
Although this is an excited state, it is not singular, unlike all previous
finite volume descriptions. We use our states to model the processes of pair
creation and annihilation.Comment: Six EPS figures. Version 2: minor typos correcte
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