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SUMMARY:Marco Bonvini\, "Uncertainties from missing higher orders in pertu
rbative computations"
DTSTART;VALUE=DATE-TIME:20190606T140000Z
DTEND;VALUE=DATE-TIME:20190606T150000Z
DTSTAMP;VALUE=DATE-TIME:20200217T004547Z
UID:indico-event-1717@cern.ch
DESCRIPTION:In many branches of physics\, and in particular in quantum fie
ld theory\, the perturbative approach offers a powerful tool for making th
eoretical predictions. When the expansion parameter is not small enough\,
as it happens in quantum chromodynamics\, and the number of computable ord
ers is limited\, it becomes very important to be able to estimate the unce
rtainty on a theoretical prediction due to the missing higher orders. This
is particularly important when comparing theory with data\, e.g. for the
precision physics programme of the LHC.\nI will review the standard method
\, which is based on unphysical scale variation. While scale variation is
certainly a good tool to guess the size of the next perturbative order\, i
t lacks of a probabilistic interpretation and it often underestimates the
actual uncertainty. A few years ago Cacciari and Houdeau proposed a Bayesi
an model to give a statistical meaning to theory uncertainties. I will rev
iew the Cacciari-Houdeau approach\, and present new models which overcomes
some of the limitations of the original one. I will further show how scal
e dependence can be removed from a finite-order result within the context
of these models. As a proof of concept\, I will apply the methods to inclu
sive Higgs production in gluon fusion\, for which four perturbative orders
are known\, and which is characterised by large perturbative corrections.
\n\nhttps://indico.nikhef.nl/event/1717/
LOCATION:Nikhef
URL:https://indico.nikhef.nl/event/1717/
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