We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
New NLOPS predictions for tt¯+b-jet production at the LHC.
- Authors
Ježo, Tomáš; Lindert, Jonas M.; Moretti, Niccolo; Pozzorini, Stefano
- Abstract
Measurements of tt¯H<inline-graphic></inline-graphic> production in the H→bb¯<inline-graphic></inline-graphic> channel depend in a critical way on the theoretical uncertainty associated with the irreducible tt¯+b<inline-graphic></inline-graphic>-jet background. In this paper, analysing the various topologies that account for b-jet production in association with a tt¯<inline-graphic></inline-graphic> pair, we demonstrate that the process at hand is largely driven by final-state g→bb¯<inline-graphic></inline-graphic> splittings. We also show that in five-flavour simulations based on tt¯+<inline-graphic></inline-graphic>multi-jet merging, b-jet production is mostly driven by the parton shower, while matrix elements play only a marginal role in the description of g→bb¯<inline-graphic></inline-graphic> splittings. Based on these observations we advocate the use of NLOPS simulations of pp→tt¯bb¯<inline-graphic></inline-graphic> in the four-flavour scheme, and we present a new POWHEG generator of this kind. Predictions and uncertainties for tt¯+b<inline-graphic></inline-graphic>-jet observables at the 13 TeV LHC are presented both for the case of stable top quarks and with spin-correlated top decays. Besides QCD scale variations we consider also theoretical uncertainties related to the POWHEG matching method and to the parton shower modelling, with emphasis on g→bb¯<inline-graphic></inline-graphic> splittings. In general, matching and shower uncertainties turn out to be remarkably small. This is confirmed also by a consistent comparison against SHERPA+OPENLOOPS.
- Subjects
PARTONS; QUANTUM chromodynamics; LARGE Hadron Collider; QUARKS; MONTE Carlo method
- Publication
European Physical Journal C -- Particles & Fields, 2018, Vol 78, Issue 6, p1
- ISSN
1434-6044
- Publication type
Article
- DOI
10.1140/epjc/s10052-018-5956-0