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Horace Event Generator Home Page
Horace is a Monte Carlo event generator for Drell-Yan
pp --> l ν X, l+l- X
processes at hadron colliders (e.g. Tevatron and LHC).
It includes the exact 1-loop electroweak radiative corrections
matched with a QED Parton Shower to take into account also
higher-order QED leading effects;
it can run also including only final-state QED corrections in a Parton
Shower approach.
The current authors of the code are
C.M. Carloni Calame [a],
G. Montagna [a,b],
O. Nicrosini [a],
A. Vicini [d] (notice the anti-spam [#] in the e-mail addresses!).
[a] INFN, Sezione di Pavia
[b] Dipartimento di Fisica Nucleare e Teorica of the Università
degli Studi di Pavia (Italy)
[c] Dipartimento di Fisica dell'Università degli Studi di
Milano (Italy) and INFN, Sezione di Milano
The latest version of Horace is 3.2.
Please stay tuned at this page for updates of the generator.
We would be very grateful to you if you could send an e-mail to one of the
authors after downloading the generator, so that we can inform you about
updates of the code, publications, etc.
We would be also very grateful to you if you could cite the following papers
when referring to Horace:
[1] C.M. Carloni Calame, G. Montagna, O. Nicrosini and A. Vicini,
"Precision electroweak calculation of the production of a high
transverse-momentum lepton pair at hadron colliders", JHEP
0710:109,2007 (arXiv:0710.1722
[hep-ph])
[2] C.M. Carloni Calame, G. Montagna, O. Nicrosini and A. Vicini, in
the proceedings of Tevatron-for-LHC "Tevatron-for-LHC Report: Top and
Electroweak Physics"
(arXiv:0705.3251 [hep-ph])
[3] C.M. Carloni Calame, G. Montagna, O. Nicrosini and A. Vicini,
"Precision electroweak calculation of the charged current Drell-Yan process",
JHEP 0612 (2006) 016
(hep-ph/0609170)
[4] C.M. Carloni Calame, G. Montagna, O. Nicrosini and A. Vicini,
in the proceedings of
Les Houches 2005 "Physics at TeV colliders. The QCD, EW and Higgs
working group: Summary Report"
(hep-ph/0604120)
[5] C.M. Carloni Calame, G. Montagna, O. Nicrosini and M. Treccani, JHEP 0505 019, 2005
(hep-ph/0502218)
[6] C.M. Carloni Calame, G. Montagna, O. Nicrosini and M. Treccani,
Phys. Rev. D 69 037301, 2004
(hep-ph/0303102)
In paper [1], the effects
of order α and higher order QED corrections to the neutral
current process are discussed in detail.
In paper [3],
a detailed description of the matching procedure between
O(α) and higher order leading QED effects is presented, together
with the recipe to subtract to all orders initial state collinear
singularities. The phenomenology of several electroweak observables
for the W production is discussed in detail.
In paper [2] and
[4],
several tuned comparisons against other O(α) electroweak event
generators have been performed, checking the reliability of the code.
In paper
[5],
a detailed study of the neutral current process is presented.
Finally, in paper
[6],
a study of the impact of higher-order multiple-photon effects in the
extraction of the W mass from data is discussed.
Horace 3.2
Version used for the Drell-Yan comparison described in
Precisions
Studies of Observables in Drell-Yan processes at LHC. The
results are published
here and the code
is available here.
With respect to version 3.1, version 3.2 improves the generation
efficiency, fixes some minor bugs and upgrades the external
libraries Cuba and
LoopTools to version 4.2 and 2.13 respectively
(properly patched to work within Horace). Horace is now interfaced by
default to LHAPDF parton distribution functions.
Please refer to
the README-horace-3.2 file for a
list of changes, a description of the input variables and
instructions to reproduce the report results.
Horace 3.1 bug fix
We found a bug in Horace 3.1, introduced in the change from version
3.0. A quick solution of the problem is to replace in the directory
LoopTools2-withD0cm/fortran/ the files Dget.F and Cget.F with the
corrected ones which can be downloaded here
(Dget.F and Cget.F). In
order to compile and link the correct libraries, go to the directory
LoopTools2-withD0cm/, issue the commands "rm *_objs*" and "make
libooptools.a", go to the parent directory, remove the Horace
executable and rebuild it.
Horace 3.1
This version (Download it here)
is mainly a bug fixing release of the generator.
Please refer to the README-horace-3.1
file in the package for its usage and a short description of the
changes.
Horace 3.0 bug fix
We found a bug in Horace 3.0 when it runs in "new" mode at order
"alpha", only when W production is selected. Please replace your
matching.f file with this one. Soon
a bug fix release of Horace 3.0 will be available, where some issues
pointed out by some of the users are fixed.
Horace 3.0
In this version (Download it here),
the exact O(α) electroweak virtual and real
corrections to the neutral current process are also included.
They are matched with a QED Parton Shower to take into account
the leading QED effects to all orders.
The generator can also be run by including only final-state QED
radiation in the Parton Shower approximation.
The code can be used to generate both weighted and unweighted events.
Please refer to the README-horace-3
file in the package for its usage.
Horace 2.0 (superseded by Horace 3.0)
In the charged-current channel,
this version
(Download it here)
is a complete rewriting of the generator.
It includes the exact O(α) electroweak virtual and real
corrections, which are matched with the leading QED effects to all
orders.
It can still be run including only final-state QED radiation, as in
the previous version.
In the neutral-current channel at the moment only the final-state
leading QED corrections to all orders are included, but the upgrade to
exact O(α) electroweak matched with higher orders QED is foreseen.
The code can be used to generate both weighted and unweighted events.
Please refer to the README-HORACE file in the package for its usage.
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