QCD resummation techniques applied to beyond the standard model physics

Who: Benjamin Fuks (University of Strasbourg)
When: Monday, November 5, 2012 at 14:15
Where: U49

When studying the transverse-momentum (pT) distribution of a produced colorless final state, it is convenient to separate the large- and small-pT regions. For the large values of pT, the use of the fixed-order perturbation theory is fully justified, but in the small-pT region, the coefficients of the perturbative expansion are enhanced by powers of large logarithmic terms. Furthermore, at the production threshold, the mismatch between virtual corrections and phase-space suppressed real-gluon emission leads also to the appearance of large logarithmic terms. Accurate theoretical calculations must then include soft-gluon resummation in order to obtain reliable perturbative predictions and properly take these logarithms into account.

We present precision calculations for slepton-pair, gaugino-pair and Z’ production at hadron colliders, matching transverse-momentum spectra, invariant-mass distributions and total cross sections obtained with the use of resummation with those obtained through pure perturbative calculations. We compare then the resummed results with those provided by Monte Carlo generators such as MC@NLO, PYTHIA or MadGraph (including a matching a la MLM), and study the impact of scale variations, parton densities, and non-perturbative effects.

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