Abstract
We use HERWIRI1.031, a new Monte Carlo event generator for hadron-hadron scattering at high energies, to study the phenomenological effects of our approach of exact amplitude-based resummation in precision QCD calculations. W + jet(s) events with exact NLO QCD corrections are generated in the MG5_aMC@NLO framework and showered by both HERWIRI1.031 and HERWIG6.5 with PTRMS = 0 and PTRMS = 2.2 GeV/c, respectively. Here, PTRMS is the rms value of the intrinsic Gaussian transverse momentum distribution for the partons inside the proton. The differential cross sections for many observables are presented such as the jet rapidities and the jet transverse momenta as well as other event observables such as the scalar sums of transverse momenta of the jets, the missing transverse energy of the jets and the dijets' observables. Finally, we compare our results with the ATLAS and CMS measurements of the W production cross sections in association with jets.
Highlights
In the precision theory of the Standard Model (SM), since we are dealing with the computation of the higher order Feynman diagrams in which the virtual and real radiative corrections are involved, the treatment of the ultraviolet (UV), infrared (IR), and collinear singularities plays a crucial role
Can show that the exact, amplitude-based resummation leads to the IR improvement of the usual DGLAP-CS theory [10,11,12,13], which results in a new set of kernels, parton distributions, and attendant reduced cross sections, so that the QCD perturbative results for the respective hadronhadron or lepton-hadron cross section are unchanged order by order in αs at large squared-momentum transfers
We extend the studies in Refs. [14,15,16,17,18,19,20], which were focused on the single Z=γà production at FNAL and LHC, to the single W production at the LHC, with the additional change that we look into the properties of jets, produced in association with the W, in relation to the physics of IR-improved DGLAP-CS kernels
Summary
In the precision theory of the Standard Model (SM), since we are dealing with the computation of the higher order Feynman diagrams in which the virtual and real radiative corrections are involved, the treatment of the ultraviolet (UV), infrared (IR), and collinear singularities plays a crucial role. One. can show that the exact, amplitude-based resummation leads to the IR improvement of the usual DGLAP-CS theory [10,11,12,13], which results in a new set of kernels, parton distributions, and attendant reduced cross sections, so that the QCD perturbative results for the respective hadronhadron or lepton-hadron cross section are unchanged order by order in αs at large squared-momentum transfers. Can show that the exact, amplitude-based resummation leads to the IR improvement of the usual DGLAP-CS theory [10,11,12,13], which results in a new set of kernels, parton distributions, and attendant reduced cross sections, so that the QCD perturbative results for the respective hadronhadron or lepton-hadron cross section are unchanged order by order in αs at large squared-momentum transfers This IR-improved behavior, for example, results in kernels that are integrable in the IR limit and are more amenable to realization by the Monte Carlo (MC) method [14,15,16,17,18,19,20] to arbitrary precision. (ii) herwig ≡ MADGRAPH5_aMC@NLO/HERWIG6.521 (PTRMS 1⁄4 2.2 GeV)
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