M. Neubert

Renormalization-group improved predictions for top-quark pair production at hadron colliders

Precision predictions for phenomenologically interesting observables such as the

Drell–Yan production at small qT, transverse parton distributions and the collinear anomaly

tbar{t}

Model-independent extraction of Vcb from semi-leptonic decays

invariant mass distribution and forward-backward asymmetry in top-quark pair production at hadron colliders require control over the differential cross section in perturbative QCD. In this paper we improve existing calculations of the doubly differential cross section in the invariant mass and scattering angle by using techniques from soft-collinear effective theory to perform an NNLL resummation of threshold logarithms, which become large when the invariant mass M of the top-quark pair approaches the partonic center-of-mass energy

The custodial Randall-Sundrum model: from precision tests to Higgs physics

sqrt {{hat{s}}}

New approach to the universal form factors in decays of heavy quarks

. We also derive an approximate formula for the differential cross section at NNLO in fixed-order perturbation theory, which completely determines the coefficients multiplying the singular plus distributions in the variable

Factorization at subleading power and irreducible uncertainties in \( \bar{B} \to {X_s}\gamma \) decay

left( {1 - {{{{M^2}}} left/ {{hat{s}}} right.}} right)

Renormalization of heavy-quark currents

. We then match our results in the threshold region with the exact results at NLO in fixed-order perturbation theory, and perform a numerical analysis of the invariant mass distribution, the total cross section, and the forward-backward asymmetry. We argue that these are the most accurate predictions available for these observables at present. Using MSTW2008NNLO parton distribution functions (PDFs) along with αs(MZ) = 0.117 and mt = 173.1 GeV, we obtain for the inclusive production cross sections at the Tevatron and LHC the values

Quark-quark correlations and the λI=12 rule

{{{sigma }}_{text{Tevatron}}} = left( {6.30pm 0.19_{ - 0.23}^{ + 0.31}} right){text{pb}}

EFFECTIVE FIELD THEORY AND HEAVY QUARK PHYSICS

and σLHC = (149 ± 7 ± 8) pb, where the first error results from scale variations while the second reflects PDF uncertainties.

Photon production in ultrarelativistic heavy-ion collisions at 200 GeV/u

Using methods from effective field theory, an exact all-order expression for the Drell–Yan cross section at small transverse momentum is derived directly in qT space, in which all large logarithms are resummed. The anomalous dimensions and matching coefficients necessary for resummation at NNLL order are given explicitly. The precise relation between our result and the Collins–Soper–Sterman formula is discussed, and as a by-product the previously unknown three-loop coefficient A(3) is obtained. The naive factorization of the cross section at small transverse momentum is broken by a collinear anomaly, which prevents a process-independent definition of xT-dependent parton distribution functions. Axa0factorization theorem is derived for the product of two such functions, in which the dependence on the hard momentum transfer is separated out. The remainder factors into a product of two functions of longitudinal momentum variables and