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SUMMARY:Probabilistic definition of the perturbative theoretical uncertain
 ty from missing higher orders - Marco Bonvini (INFN Rome)
DTSTART:20210518T150000Z
DTEND:20210518T160000Z
UID:TALK159169@talks.cam.ac.uk
CONTACT:Heribertus Bayu Hartanto
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 improve s
 ignificantly the accuracy of the original approach. I will further show ho
 w scale dependence can be "removed" from a perturbative result within the 
 context of these models.
LOCATION:https://cern.zoom.us/j/61144924828?pwd=WDB6QmFCMEZiSEN5Q0k2aklWSj
 k5Zz09
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