Interplay between IR-improved DGLAP-CS theory and the precision of an NLO ME matched parton shower MC in relation to LHCb data

Abstract

We use comparison with recent LHCb data on single [Formula: see text] production and decay to lepton pairs as a vehicle to study the current status of the application of our approach of exact amplitude-based resummation in quantum field theory to precision quantum chromodynamics (QCD) calculations, by realistic MC event generator methods, as needed for precision large hadron collider (LHC) physics. This represents an extension of the phase space of our previous studies based on comparison with CMS and ATLAS data, as the pseudo-rapidity range measured by the LHCb for leptons in the data we study is 2.0 [Formula: see text] 4.5 to be compared with [Formula: see text] 4.6(2.4) in our previous CMS(ATLAS) data comparison for the same processes. To be precise, for [Formula: see text] decays, the CMS data had [Formula: see text] 2.1 while, for [Formula: see text] decays, the CMS data had [Formula: see text] 2.1 for both leptons for the [Formula: see text][Formula: see text] spectrum and had one lepton with [Formula: see text] 2.5 and one with [Formula: see text] 4.6 for the [Formula: see text] rapidity spectrum. The analyses we present here with the LHCb data thus represent an important addition to our previous results, as it is essential that theoretical predictions be able to control all of the measured phase space at LHC. The level of agreement between the new theory and the data continues to be a reason for optimism.