22 research outputs found
Photon Splitting in a Strong Magnetic Field: Recalculation and Comparison With Previous Calculations
We recalculate the amplitude for photon splitting in a strong magnetic field
below the pair production threshold, using the worldline path integral variant
of the Bern--Kosower formalism. Numerical comparison (using programs that we
have made available for public access on the Internet) shows that the results
of the recalculation are identical to the earlier calculations of Adler and
later of Stoneham, and to the recent recalculation by Baier, Milstein, and
Shaisultanov.Comment: Revtex, 9 pages, no figure
Zero modes, beta functions and IR/UV interplay in higher-loop QED
We analyze the relation between the short-distance behavior of quantum field
theory and the strong-field limit of the background field formalism, for QED
effective Lagrangians in self-dual backgrounds, at both one and two loop. The
self-duality of the background leads to zero modes in the case of spinor QED,
and these zero modes must be taken into account before comparing the
perturbative beta function coefficients and the coefficients of the
strong-field limit of the effective Lagrangian. At one-loop this is familiar
from instanton physics, but we find that at two-loop the role of the zero
modes, and the interplay between IR and UV effects in the renormalization, is
quite different. Our analysis is motivated in part by the remarkable simplicity
of the two-loop QED effective Lagrangians for a self-dual constant background,
and we also present here a new independent derivation of these two-loop
results.Comment: 15 pages, revtex
Next-to-leading order QCD predictions for W+2j and Z+2j production at the CERN LHC
We present cross sections and differential distributions for QCD radiative
corrections to the QCD processes pp -> W+2j and pp -> Z+2j at the CERN LHC.
Calculations are performed with the Monte Carlo program MCFM. Cross section
dependence on the renormalization and factorization scales is greatly reduced,
except for the heavy-flavor case of Wbb~, which has new features at
next-to-leading order at the LHC. We also present cross sections for Wbb~ and
Z+2j in kinematic configurations relevant for Higgs boson searches.Comment: 24p, PRD version, ref's corrected, add. paragraph to explain pTmiss
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