4 research outputs found
Two-Loop Helicity Amplitudes for Quark-Quark Scattering in QCD and Gluino-Gluino Scattering in Supersymmetric Yang-Mills Theory
We present the two-loop QCD helicity amplitudes for quark-quark and
quark-antiquark scattering. These amplitudes are relevant for
next-to-next-to-leading order corrections to (polarized) jet production at
hadron colliders. We give the results in the `t Hooft-Veltman and
four-dimensional helicity (FDH) variants of dimensional regularization and
present the scheme dependence of the results. We verify that the finite
remainder, after subtracting the divergences using Catani's formula, are in
agreement with previous results. We also provide the amplitudes for
gluino-gluino scattering in pure N=1 supersymmetric Yang-Mills theory. We
describe ambiguities in continuing the Dirac algebra to D dimensions, including
ones which violate fermion helicity conservation. The finite remainders after
subtracting the divergences using Catani's formula, which enter into physical
quantities, are free of these ambiguities. We show that in the FDH scheme, for
gluino-gluino scattering, the finite remainders satisfy the expected
supersymmetry Ward identities.Comment: arXiv admin note: substantial text overlap with arXiv:hep-ph/030416
corrections to the polar angle dependence of the longitudinal spin-spin correlation asymmetry in
We provide analytical results for the corrections to the polar
angle dependence of the longitudinal spin-spin correlation asymmetry in
. For top quark pair production the
corrections to the longitudinal spin-spin asymmetry are strongly polar angle
dependent and can amount up to in the -range from above
threshold up to GeV. The radiative corrections
to the correlation asymmetry are below in the forward direction where the
cross section is largest. In the case the
corrections reduce the asymmetry value from its value of to
approximately for -values around the peak and are practically
independent of the value of the polar angle theta. This reduction can be traced
to finite anomalous contributions from residual mass effects which survive the
limit. We discuss the role of the anomalous contributions and the
pattern of how they contribute to spin-flip and non-flip terms.Comment: 32 pages written in LaTeX, including 8 encapsulated postscript
figures and 2 tables; v2: corrections according to the erratu