Abstract
We study the impact of different theoretical descriptions of top quark pair production on top quark mass measurements in the di-lepton channel. To this aim, the full NLO corrections to ppto {W}^{+}{W}^{-}boverline{b}to left({e}^{+}{nu}_eright)left({mu}^{-}{overline{nu}}_{mu}right)boverline{b} production are compared to calculations in the narrow width approximation, where the production of a top quark pair is calculated at NLO and combined with three different descriptions of the top quark decay: leading order, next-to-leading order and via a parton shower. The different theory predictions then enter the calibration of template fit functions, which are used for a fit to pseudo-data. The offsets in the top quark mass resulting from the fits based on the various theoretical descriptions are determined.
Highlights
Distributions are known [22,23,24] and have recently been combined with NLO electroweak corrections [25]
We study the impact of different theoretical descriptions of top quark pair production on top quark mass measurements in the di-lepton channel
We have studied the impact of various theoretical descriptions for top quark pair production on measurements of the top quark mass in the di-lepton channel
Summary
We study the following descriptions of top quark pair production in the di-lepton channel: NLOfull: full NLO corrections to pp → W +W −bb with leptonic W -decays, NLONNLWOAdec: NLO ttproduction ⊗ NLO decay, NLOLNOWdAec: NLO ttproduction ⊗ LO decay, NLOPS: NLO ttproduction+shower ⊗ decay via parton showering. Plus Sherpa [64], version 2.2.3, where the virtual corrections generated by GoSam are linked to Sherpa via the Binoth-Les-Houches-interface [67, 68] This applies to the calculations NLOfull and NLOLNOWdAec and to the NLOPS computation. For our studies relying on NLOLNOWdAec results, we remove all contributions in the second line of eq (2.4) and use ΓLt,OW instead of ΓNt,WLO This treatment guarantees that dPS |Dt→blν|2 = BR(t → blν) at LO and NLO, with BR(t → blν) denoting the branching ratio for the top quark decay. In the course of this work, it was found that this version treats radiation emerging from top quark decays in resonant top quark processes in the same manner as radiation arising from continuum production processes This resulted in an omission of the initial-state spectator mass term that suppresses the ordinary eikonal radiation of continuum initial-final dipoles. It will be made available on the corresponding software download pages, and included in the Sherpa program from version 2.2.5 onwards
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