Related papers: Nonperturbative Corrections in Resummed Cross Sect…
The resummed Drell-Yan cross section in the double-logarithmic approximation suffers from infrared renormalons. Their presence was interpreted as an indication for non-perturbative corrections of order $\lqcd/(Q(1-z))$. We find that, once…
We discuss the role of infrared renormalons in power corrections to hadronic cross sections, including their universality. We show how perturbative renormalon structure arises near kinematic boundaries in the thrust distribution, the…
Resummation of large infrared logarithms in perturbation theory can, in certain circumstances, enhance the sensitivity to small gluon momenta and introduce spurious nonperturbative contributions. In particular, different procedures --…
We present a new resummation formula for the Drell-Yan cross section. The formal resummation of threshold corrections in Drell-Yan hard-scattering functions produces an exponent with singularities from the infrared pole of the QCD running…
We present results for higher order perturbative corrections to Compton scattering in the generalized Bjorken kinematics. The approach we have used is based on the combination of two techniques: conformal operator product expansion on the…
We discuss corrections from the elastic limit (partonic threshold) in hadronic hard-scattering cross sections. We show why these corrections can be large at all orders in perturbation theory, and describe their resummation to arbitrary…
The `renormalon' or `dispersive' method for estimating non-perturbative corrections to QCD observables is reviewed. The corrections are power-suppressed, i.e. of the form $A/Q^p$ where $Q$ is the hard process momentum scale. The renormalon…
Precise theoretical predictions are a key ingredient for an accurate determination of the structure of the Langrangian of particle physics, including its free parameters, which summarizes our understanding of the fundamental interactions…
We consider $1/Q$ corrections to hard processes in QCD where Q is a large mass scale, concentrating on shape variables in $e^{+}e^{-}$ annihilation. While the evidence for such corrections can be and has been established by means of the…
We study the effect of infrared renormalons upon shape variables that are commonly used to determine the strong coupling constant in $e^+e^-$ annihilation into hadronic jets. We consider the model of QCD in the limit of large $n_f$. We find…
Even for short-distance dominated observables the QCD perturbation expansion is never complete. The divergence of the expansion through infrared renormalons provides formal evidence of this fact. In this article we review how this apparent…
The large-order behaviour of QCD is dominated by renormalons. On the other hand renormalons do not occur in conformal theories, such as the one describing the infrared fixed-point of QCD at small beta_0 (the Banks--Zaks limit). Since the…
Modifications of the QCD perturbative expansions by the subtraction of the dominant infrared renormalon have been proposed recently as attempts to solve the long-standing discrepancy between fixed-order and contour-improved perturbation…
This thesis arises in the context of precision measurements at hadron colliders. The Tevatron and the LHC provide very accurate measurements of many Standard Model processes, such as the production of a lepton pair (Drell-Yan) of high…
A certain pattern of divergence of perturbative expansions in quantum field theories, related to their small and large momentum behaviour, is known as renormalons. We review formal and phenomenological aspects of renormalon divergence. We…
I give a short review of the relation of infrared renormalons in QCD and higher twist effects, with the emphasis on possible applications. In particular, I present estimates of renormalon-induced uncertainties in deep inelastic sum rules…
Infrared renormalons and $1/Q^2$ power corrections in deep-inelastic sum rules are studied. The renormalization of operators with power divergence are discussed. The higher-twist terms in the operator product expansion are shown to account…
Ultraviolet renormalons, contrary to their infrared counterparts, lead to a universal contribution to the large-order behaviour of perturbative expansions in QCD. In this letter, we determine nature of the leading ultraviolet renormalon…
The main obstacle in describing inclusive decay spectra in QCD - which, in particular, limits the precision in extrapolating the measured \bar{B} \to X(s) gamma rate to the full phase space as well as in extracting |V_{ub}| from inclusive…
We study the asymptotic behaviour of the perturbative series in the heavy quark effective theory (HQET) using the $1/N_f$ expansion. We find that this theory suffers from an {\it ultraviolet} renormalon problem, corresponding to a…