227 research outputs found
Interplay between perturbative and non-perturbative effects in the stealthy Higgs model
We study corrections to electroweak precision variables in a model with
strongly interacting singlet Higgs particles.Comment: 31 pages, Latex, 11 figure
Power Corrections and KLN Cancellations
We consider perturbative expansions in theories with an infrared cutoff
. The infrared sensitive pieces are defined as terms nonanalytic in
the infinitesimal and powers of this cutoff characterize the
strength of these infrared contributions. It is argued that the sum over the
initial and final degenerate ( as ) states which is required by
the Kinoshita - Lee - Nauenberg theorem eliminates terms of order
and . However, the quadratic and higher order terms in general do
not cancel. This is investigated in simple examples of KLN cancellations, of
relevance to the inclusive decay rate of a heavy particle, at the one loop
level.Comment: 20 pages, LaTe
Renormalons and 1/Q^2 Corrections
We argue that the appearance of the Landau pole in the running coupling of
QCD introduces 1/Q^2 power corrections in current correlation functions. These
terms are not accounted for by the standard operator product expansion and is
the price to be paid for the lack of a unique definition of the running
coupling at the 1/Q^2 level. We review also possible phenomenological
implications of the 1/Q^2 terms in an alternative language of the ultraviolet
renormalon.Comment: 7 pages, LaTe
On Non Perturbative Corrections to the Potential for Heavy Quarks
We discuss non perturbative corrections to the Coulomb-like potential of
heavy quarks at short distances. We consider both the standard framework
provided by infrared renormalons and the assumption that confinement does not
allow weak fields to penetrate the vacuum. In the former case the leading
correction at short distances turns out to be quadratic in r for static quarks.
In the latter case we find a potential which is proportional to r as r
rightarrow 0. We point out that similar effects arise due to a new kind of non
perturbative correction proportional to 1/Q^2, which is unaccounted for by the
operator product expansion and which was recently discussed within a different
framework.
Phenomenological implications of the linear correction to the potential are
briefly reviewed.Comment: 13 pages, latex, 2 figures, uses eps
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