Manual BOX Zj
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Preprint typeset in JHEP style - PAPER VERSION March 16, 2011
POWHEG BOX 1.0
The POWHEG BOX user manual:
Z+ 1 jet production
Simone Alioli
Deutsches Elektronen-Synchrotron DESY
Platanenallee 6, D-15738 Zeuthen, Germany
E-mail: simone.alioli@desy.de
Paolo Nason
INFN, Sezione di Milano-Bicocca, Piazza della Scienza 3, 20126 Milan, Italy
E-mail: Paolo.Nason@mib.infn.it
Carlo Oleari
Universit`a di Milano-Bicocca and INFN, Sezione di Milano-Bicocca
Piazza della Scienza 3, 20126 Milan, Italy
E-mail: Carlo.Oleari@mib.infn.it
Emanuele Re
Institute for Particle Physics Phenomenology, Department of Physics
University of Durham, Durham, DH1 3LE, UK
E-mail: emanuele.re@durham.ac.uk
Abstract: This note documents the use of the package POWHEG BOX for Z+1 jet production
processes. Results can be easily interfaced to shower Monte Carlo programs, in such a way
that both NLO and shower accuracy are maintained.
Keywords: POWHEG, Shower Monte Carlo, NLO.
Contents
1. Introduction 1
2. Generation of events 1
3. Process specific input parameters 2
1. Introduction
The POWHEG BOX program is a framework for implementing NLO calculations in Shower
Monte Carlo programs according to the POWHEG method. An explanation of the method
and a discussion of how the code is organized can be found in refs. [1, 2, 3]. The code is
distributed according to the “MCNET GUIDELINES for Event Generator Authors and
Users” and can be found at the web page
http://powhegbox.mib.infn.it.
In this manual, we describe the POWHEG NLO implementation of Z+1 jet hadroproduction,
with Z→`+`−fully taken into account at leading order, as described in ref. [4]
2. Generation of events
Build the executable
$ cd POWHEG-BOX/Zj
$ make pwhg main
Then do (for example)
$ cd testrun-lhc
$ ../pwhg main
At the end of the run, the file pwgevents.lhe will contain 50000 events for Z+ 1 jet
hadroproduction in the Les Houches format. By replacing the powheg.input file with
the alternative alt-powheg.input, the program is run in the weighted-event mode (see
ref. [4]).
In order to shower them with PYTHIA do
$ cd POWHEG-BOX/Zj
$ make main-PYTHIA-lhef
$ cd testrun-lhc
$ ../main-PYTHIA-lhef
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3. Process specific input parameters
The decay of the Zboson is controlled by the token vdecaymode, in this way:
- 1 for e+e−
- 2 for µ+µ−
- 3 for τ+τ−
whose masses (physpar ml), together with all other input physical parameters, are set in
the init couplings.f file.
References
[1] P. Nason, “A new method for combining NLO QCD with shower Monte Carlo algorithms,”
JHEP 0411 (2004) 040 [arXiv:hep-ph/0409146].
[2] S. Frixione, P. Nason and C. Oleari, “Matching NLO QCD computations with Parton Shower
simulations: the POWHEG method,” JHEP 0711 (2007) 070 [arXiv:0709.2092 [hep-ph]].
[3] S. Alioli, P. Nason, C. Oleari and E. Re, “A general framework for implementing NLO
calculations in shower Monte Carlo programs: the POWHEG BOX,” [arXiv:1002.2581
[hep-ph]].
[4] S. Alioli, P. Nason, C. Oleari and E. Re, “Vector boson plus one jet production in
POWHEG,” JHEP 1101, 005 (2011) [arXiv:1009.5594 [hep-ph]].
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