67,841 research outputs found
Changes of Variables and the Renormalization Group
A class of exact infinitesimal renormalization group transformations is
proposed and studied. These transformations are pure changes of variables
(i.e., no integration or elimination of some degrees of freedom is required)
such that a saddle point approximation is more accurate, becoming, in some
cases asymptotically exact as the transformations are iterated. The formalism
provides a simplified and unified approach to several known renormalization
groups. It also suggests some new ways in which renormalization group methods
might successfully be applied. In particular, an exact gauge covariant
renormalization group transformation is constructed. Solutions for a scalar
field theory are obtained both as an expansion in {\epsilon}=4-d and as an
expansion in a single coupling constant.Comment: In v2 several typos have been correcte
Higgs Boson Production at Hadron Colliders at N3LO in QCD
We present the Higgs boson production cross section at Hadron colliders in
the gluon fusion production mode through N3LO in perturbative QCD.
Specifically, we work in an effective theory where the top quark is assumed to
be infinitely heavy and all other quarks are considered to be massless. Our
result is the first exact formula for a partonic hadron collider cross section
at N3LO in perturbative QCD. Furthermore, this result represents the first
analytic computation of a hadron collider cross section involving elliptic
integrals. We derive numerical predictions for the Higgs boson cross section at
the LHC. Previously this result was approximated by an expansion of the cross
section around the production threshold of the Higgs boson and we compare our
findings. Finally, we study the impact of our new result on the state of the
art prediction for the Higgs boson cross section at the LHC.Comment: several nice figure
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