| 1. |
- Butterworth, J., et al.
(författare)
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Les Houches 2013: Physics at TeV Colliders: Standard Model Working Group Report
- 2014
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Konferensbidrag (refereegranskat)abstract
- This Report summarizes the proceedings of the 2013 Les Houches workshop on Physics at TeV Colliders. Session 1 dealt primarily with (1) the techniques for calculating standard model multi-leg NLO and NNLO QCD and NLO EW cross sections and (2) the comparison of those cross sections with LHC data from Run 1, and projections for future measurements in Run 2.
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| 2. |
- Lönnblad, Leif, et al.
(författare)
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Matching tree-level matrix elements with interleaved showers
- 2012
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :3
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Tidskriftsartikel (refereegranskat)abstract
- We present an implementation of the so-called CKKW-L merging scheme for combining multi-jet tree-level matrix elements with parton showers. The implementation uses the transverse-momentum-ordered shower with interleaved multiple interactions as implemented in PYTHIA8. We validate our procedure using e(+)e(-)-annihilation into jets and vector boson production in hadronic collisions, with special attention to details in the algorithm which are formally sub-leading in character, but may have visible effects in some observables. We find substantial merging scale dependencies induced by the enforced rapidity ordering in the default PYTHIA8 shower. If this rapidity ordering is removed the merging scale dependence is almost negligible. We then also find that the shower does a surprisingly good job of describing the hardness of multi-jet events, as long as the hardest couple of jets are given by the matrix elements. The effects of using interleaved multiple interactions as compared to more simplistic ways of adding underlying-event effects in vector boson production are shown to be negligible except in a few sensitive observables. To illustrate the generality of our implementation, we also give some example results from di-boson production and pure QCD jet production in hadronic collisions.
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| 5. |
- Prestel, Stefan
(författare)
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Improving Parton Showers with Fixed Order Matrix Elements
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis considers numerical simulations of high energy particle collisions, and improvements in the description of multiple collimated jets of hadrons in collision events in particular. In the event simulation software called event generators, the structure of multi-jet events is determined through an interplay of the input calculation, parton showers and phenomenological hadronisation models. Prescriptions to imbue existing event generator simulations with more complex input calculations are presented, and public implementations of the proposed methods provided. Paper I describes the implementation of an earlier algorithm to include regularised tree-level multi-jet configurations into event generators. The implementation is applied to collisions at LEP, Tevatron and LHC. Paper II proposes a method to amend cross section changes in traditional multi-jet merging schemes. The implementation of the new scheme is tested for W-boson + jets and QCD Dijet production at the LHC. Paper III presents extensions of the algorithms of Papers I and II to allow the inclusion of virtual orrections to the scattering processes. The resulting NLO merging methods are applied to W-boson + jets and Higgs-boson + jets at the LHC.
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