NLOJET++ is a C++ library for calculating next-to-leading order jet cross sections in e⁺e^- annihilation and in deep inelastic scattering. In the e⁺e^- case the program can calculate three- and four-jet cross section at NLO level and five-jet cross section at LO level. In the DIS case it can calculate (2+1)- and (3+1)-jet cross sections at NLO level and (4+1)-jet cross section at LO level.
 

Download and compile

The current version (1.0.0) of the program can be downloaded from here. This version is stable on linux system only. I hope in the near future I can write a platform independent version. In my program I use only standard features (standard C++, C99, POSIX,..), but most of the operating systems (e.g. alphaev6-dec-osf4.0f) don't know these standards. To compile it you should do the following steps:

% cat nlojet++-1.0.0.tar.gz | gunzip | tar xvf -
% mkdir bld-nlojet
% cd bld-nlojet
% ../nlojet++-1.0.0/configure
% make install CFLAGS="-O3 -Wall" CXXFLAGS="-O3 -Wall"

These commands will install the executable, library and include files to your home directory into the ${HOME}/bin, ${HOME}/lib and ${HOME}/include directories respectively. If you want to change the install directory then at the configuration step run the configure script with the --prefix=PATH.

Compile the demos and start a calculation

There are some demos in the demo directory. To compile and to obtain the executable file use the following commands:

% cd demo/demo-dis/demo-c++
% make all

or if you prefer the FORTRAN

% cd demo/demo-dis/demo-f
% make all

The command create-nlojet-user create the executable file demo.exe which can be started to calculate what you want. Now you can start for example two-jet calculations in DIS by

% demo1.exe -j2 -pdis -cfull -ndemo2a -m
% demo1.exe -j2 -pdis -cfull -ndemo2b -m

or three-jet calculations by

% demo1.exe -j3 -pdis -cfull -ndemo3a -m
% demo1.exe -j3 -pdis -cfull -ndemo3b -m

See all the available options of the program by demo.exe --help. The program will save the results to a file after every 10000 Monte Carlo points. In the other shell (but in this directory) you can see the results by

% nlojet-add -j2 -pdis test2a test2b

and in the three-jet case

% nlojet-add -j2 -pdis test3a test3b

One of these commands will save the results to the directory result. The results file (an example) contains nine coloumn. The first, second, third coloumns are the lower edge, middle and upper edge of the bin. The fourth and the fifth coloumns are the contribution of the gluon and its statistical error. The sixth and the seventh cols are the contribution of the up type quarks and its error, the eighth and the ninth cols are the down type quarks contributions. The tenth and the eleventh cols are the whole cross section and its statistical error.

User defined functions (C++)

This page is not yet finised. See the demo files for more information.

User defined functions (FORTRAN)

This page is not yet finised. See the demo files for more information.