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Top++: Computer program for the calculation of the total top-pair cross-section at hadron colliders
Top++: Computer program for the calculation of the total top-pair cross-section at hadron colliders
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Authors
:
(Aachen) and
Alexander Mitov
(CERN).
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Version
: 2.0 (it adds the exact NNLO result for g
g
→ tt + X from
M. Czakon, P. Fiedler and A. Mitov arXiv:1303.6254
to the previously available NNLO results for
qg
→ tt + X from
,
qq → tt + X ; qqbar' → tt + X ; qq' → tt + X from
and qqbar → tt + X from
).
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Programing language
: C++.
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Download
:
Go to downloads page
.
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Installation instructions and manual
: can be found inside the distributed software; see also below.
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Purpose
: The program calculates the total inclusive cross-section for top-pair production at hadron colliders like the Tevatron and LHC. The program is capable of calculating the cross-section in fixed order QCD with exact NNLO. The program can also perform full NNLL soft gluon resummation. The resummation is done in Mellin space and then inverted numerically to x-space via the so-called Minimal Prescription.
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Software expertise needed to operate the program
: None. Once the program has been installed (which itself is trivial; you can ask a colleague or your system administrator for help) the only point of interaction with the program is the text file
top++.cfg
. This file can be edited with a text editor, then saved, followed by typing the command
./top++
to execute the program.
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Functionality
: The program offers a large number of settings. The default setting corresponds to the best prediction of the paper by
M. Czakon, P. Fiedler and A. Mitov arXiv:1303.6254
and also by
M. Cacciari, M. Czakon, M. Mangano, A. Mitov and P. Nason
,
. The user can choose between fixed order calculation and a resummed one matched to a given perturbative order (up to NNLO+NNLL). For a discussion of the various options and a comparison between them (and how to interpret the differences) see the article mentioned above.
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Dependencies
: The program requires two standard external libraries:
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GSL (GNU scientific library)
It provides one dimensional integration routines and few special functions.
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LHAPDF
: the Les Houches parton densities library.
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Installation
: unarchive the program in a convenient directory. Then specify the C++ compiler and paths to libraries (if non-standard) inside the file
makefile
. Then type
make
. Finally type the command
./top++
The output will appear on the screen and inside the output file
top++.res
. The program has been tested with the
GCC (GNU compiler collection)
C++ compiler on a Linux and Mac OSX (10.6) platforms.
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Program settings
: The program comes with a default set of settings corresponding to the best prediction of
M. Czakon, P. Fiedler and A. Mitov arXiv:1303.6254
. To override any of the default options one has to type the desired option, and its value, in the file
top++.cfg
. After the file has been modified, it needs to be saved and then the program executed as usual. Please note that the file
top++.cfg
represents the only point of contact between the user and the program, i.e. unless the user wishes to modify the program itself, he/she will not need to ever open another file besides
top++.cfg
. If any other file has been edited/modified (to modify the default settings located in the file
top++.cpp
for example), one has to first type
make
and then execute the program again, as described above.
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Questions/Comments/Suggestions
: The authors would appreciate any comments, suggestions or questions you might have.
We can be contacted here
.
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Acknowledgements
: The authors would like to thank Matteo Cacciari, Michelangelo Mangano and Paolo Nason for numerous cross-checks and a very fruitful collaboration
that led to the creation of this software. We also thank Juan Rojo, Graeme Watt and Malgorzata Worek for useful suggestions.
Last Updated ( Tuesday, 26 March 2013 10:18 )