Abstract
This paper is a follow-up of Ref. Ferrario Ravasio et al. (Eur Phys J C 78:458, 2018. arXiv:1801.03944), where we studied the impact of next-to-leading order calculations merged with parton shower generators (NLO+PS) of increasing accuracy in the extraction of the top mass at hadron colliders. Here we examined results obtained with the older (fortran-based) shower generators Pythia6.4 and Herwig6.5. Our findings are in line with what we found in Ref. Ferrario Ravasio et al. (2018) with the new, c++-based, generators Pythia8.2 and Herwig7.1.
Highlights
In Ref. [1] we considered three NLO+PS generators for ttproduction, hvq [2], ttdec [3], and bb4 [4], implemented in the POWHEG BOX [5,6,7,8], interfaced with either Pythia8.2 (Py8.2) [9] or Herwig7.1 (Hw7.1) [10,11]
We focused on an observable that mimics those used in direct top mass measurements, and included in our study the proposed top mass measurements from the peak energy of the b jet [12] and from the class of leptonic observables suggested in Ref. [13]
3.3 Pythia versus Herwig and we plot the variation of m max Wbj and Ebmjax
Summary
In Ref. [1] we considered three NLO+PS generators for ttproduction, hvq [2], ttdec [3], and bb4 [4], implemented in the POWHEG BOX [5,6,7,8], interfaced with either Pythia8.2 (Py8.2) [9] or Herwig7.1 (Hw7.1) [10,11]. While results obtained with the three NLO+PS generators interfaced to Py8.2 are fairly consistent among each other, large differences are found if they are interfaced to Hw7.1 In this addendum we discuss the results obtained with the older, fortran-based versions of the Pythia and Herwig. It was found that switching the shower programs (to which the three NLO generators are interfaced to) yields large differences in the results, in spite of the fact. C (2019) 79:859 that the different shower programs have fairly similar formal accuracy These differences must be ascribed to the fact that different shower Monte Carlo programs may differ widely in their modeling of subleading effects, like the non-collinear radiation, the colour-reconnection schemes and the models for hadronization and multi-parton interactions. We only consider the hvq and bb generators in this addendum
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