2,288 research outputs found
Reaching NNLOPS accuracy with POWHEG and MiNLO
We describe how a simulation of Higgs boson production accurate at
next-to-next-to-leading order and matched to a parton shower can be built by
combining the POWHEG and MiNLO methods and using HNNLO results as input.Comment: 6 pages, 2 figures. Submitted to the proceedings of the LC13
Workshop, September 16-20, 2013, ECT*, Trento, Ital
Single-top production with the POWHEG method
We describe briefly the POWHEG method and present results for single-top s-
and t-channel production at hadron colliders.Comment: 5 pages, 2 figures. Submitted to the proceedings of the XVIII
International Workshop on Deep-Inelastic Scattering and Related Subjects, DIS
2010, April 19-23, 2010, Firenze, Ital
Simplified dark matter top-quark interactions at the LHC
Stringent limits on the interactions between dark matter (DM) and the
standard model can be set by studying how initial-state or final-state
particles recoil against missing transverse energy (MET). In this work, we
improve, extend and correct LHC constraints on the interactions between DM and
top quarks that are mediated by the exchange of spin-0 s-channel resonances. A
comparison of the LHC run-1 sensitivity of the two main search channels is
presented, which shows that mono-jet searches are typically more restrictive
than the MET + tbar t searches. We furthermore explore the reach of the 14 TeV
LHC. The collider constraints are compared to the restrictions arising from
direct and indirect detection as well as the DM relic abundance, and we also
reflect on effective field theory interpretations of the LHC exclusions.Comment: 29 pages, 11 figures; v4: conflict with CERN-PH-TH number fixe
Determining the structure of dark-matter couplings at the LHC
The latest LHC mono-jet searches place stringent bounds on the pp -> chibar
chi cross section of dark matter. Further properties such as the dark matter
mass or the precise structure of the interactions between dark matter and the
standard model can however not be determined in this manner. We point out that
measurements of the azimuthal angle correlations between the two jets in 2 j +
chibar chi events may be used to disentangle whether dark matter pair
production proceeds dominantly through tree or loop diagrams. Our general
observation is illustrated by considering theories in which dark matter
interacts predominantly with the top quark. We show explicitly that in this
case the jet-jet azimuthal angle difference is a gold-plated observable to
probe the Lorentz structure of the couplings of dark matter to top quarks, thus
testing the CP nature of the particle mediating these interactions.Comment: 8 pages, 5 figures; v2: discussion of signal and background cross
sections added, labelling of plots improved, typos fixed and references
updated; matches version published in PR
QCD effects in mono-jet searches for dark matter
LHC searches for missing transverse energy in association with a jet allow to
place strong bounds on the interactions between dark matter and quarks. In this
article, we present an extension of the POWHEG BOX capable of calculating the
underlying cross sections at the next-to-leading order level. This approach
enables us to consistently include the effects of parton showering and to apply
realistic experimental cuts. We find significant differences from a fixed-order
analysis that neglects parton showering effects. In particular, next-to-leading
order corrections do not lead to a significant enhancement of the mono-jet
cross section once a veto on additional jets is imposed. Nevertheless, these
corrections reduce the theoretical uncertainties of the signal prediction and
therefore improve the reliability of the derived bounds. We present our results
in terms of simple rescaling factors, which can be directly applied to existing
experimental analyses and discuss the impact of changing experimental cuts.Comment: Added KITP affiliations, fixed 2 very minor typos, matches version
published in JHE
NNLOPS accurate Drell-Yan production
We present a next-to-next-to-leading order accurate description of Drell-Yan
lepton pair production processes through or exchange that
includes consistently parton shower effects. Results are obtained by upgrading
the vector-boson plus one jet NLO calculation in POWHEG with the MiNLO
procedure and by applying an appropriate reweighting procedure making use of
the DYNNLO program. We compare to existing data and to accurate resummed
calculations.Comment: 31 pages, 17 figures, 1 tabl
NNLOPS simulation of Higgs boson production
We detail a simulation of Higgs boson production via gluon fusion, accurate
at next-to-next-to-leading order in the strong coupling, including matching to
a parton shower, yielding a fully exclusive, hadron-level description of the
final-state. The approach relies on the POWHEG method for merging the NLO Higgs
plus jet cross-section with the parton shower, and on the MINLO method to
simultaneously achieve NLO accuracy for inclusive Higgs boson production. The
NNLO accuracy is reached by a reweighting procedure making use of the HNNLO
program.Comment: 25 pages, 10 figures. Very minor clarifications in the text for v
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