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HOPPET: Higher Order Perturbative Parton Evolution Toolkit
----------------------------------------------------------
HOPPET is a Fortran 95 package for carrying out DGLAP evolution and
other common manipulations of parton distribution functions (PDFs).
The latest version can always be obtained from
http://hepforge.cedar.ac.uk/hoppet/
Within HOPPET, PDFs are represented on a grid in x-space so as to
avoid limitations on the functional form of input
distributions. Decent speed and accuracy are obtained through the
representation of splitting functions in terms of their convolution
with a set of piecewise polynomial basis functions, and Runge-Kutta
techniques are used for the evolution in Q.
Unpolarised evolution is provided in the MSbar scheme to NNLO in the
coupling, including heavy-quark thresholds, and polarised evolution to
NLO. The code is structured so as to provide simple access to the
objects representing splitting function and PDFs, making it possible
for a user to extend the facilities already provided.
F95 compilers
-------------
You need a Fortran 95 compiler to compile this package.
The free g95 (www.g95.org) compiler is one option, though its
executables are fairly slow. It is very easy to install if you don't
already have a recent version on your system. At the time of writing
the free gfortran compiler produces very slow exectuables and is not
recommended.
The intel (ifort) compiler (versions 8.1.033 upwards) exists in a
semi-free version for non-commercial use under linux and produces fast
executables.
The release has also been tested with the lahey lf95 commercial
compiler, which also generates fast code.
Compilation
-----------
Makefiles for f90/95 are generated automatically using the perl script
scripts/makef95makefile -- each f90/f95 directory contains a small
small shell script "mkmk" to coordinate the options for the Makefile
generation. Run this the first time you unpack the library, and also
if you have added any new programs or modified the "use" commands in
files.
To compile the hoppet_v1 library
cd src/
# <first edit the file "mkmk" according to your preferences>
# then generate the Makefile
./mkmk
# compile the library
make
To compile the f90 example program [not yet written...!]
cd ../example_f90
# <first edit the file "mkmk" according to your preferences>
# then generate the Makefile
./mkmk
# compile the program
make example
# <or "make program_name" for some other program>
Compiling f77 example programs (using g77) is a little trickier
because of the need to include the correct f95 libraries. Accordingly
the Makefile is not generated automatically -- look inside the
suppplied Makefile to see what needs doing.
cd ../example_f77
# <edit the Makefile directly>
# compile
make program_name
Documentation
-------------
HOPPET is (in the process of being) documented in doc/
directory. Latex the file "HOPPET-v1-doc.tex" to get the information.
======================================================================
OLD INFORMATION
======================================================================
This is a version of the PDFevln package that additionally provides a
f77 interface to allow a simple determination of convolutions of
splitting functions with a given pdf set. This is useful in various
contexts such as inclusion of factorization scale dependence in
a-posteriori inclusion of PDFs for jet calculations; or for matching
between fixed-order and resummed calculations.
To see what routines are available, and which other parameters are
around, examine src/f77_pdftab.f90
Note that compilation requires a fortran 90 compiler -- those that
have been tested (to varying extents) include ifort, lf95, g95 and
gfortran, some of which (all but lf95) are available freely to varying
extents; for initialisation g95 is found to be quite a bit slower than
the other compilers.
Complaints and questions should be addressed to
Gavin Salam <salam@lpthe.jussieu.fr>
On request the f77 interface may be extended to include easy access to
the evolution part of the package.
#-----------------------------------------------------------------
# To compile library:
#-------------------
> cd src
# edit fortran 90 compiler in Makefile if need be
> make
# then to compile example program
#--------------------------------
> cd ../example_f77
# edit Makefile so as to include the appropriate f90 and LHAPDF libraries
> make
# then run it as follows and check output against what is below
> ./convolution_example
*************************************
* LHAPDF Version 5.0 *
*************************************
>>>>>> PDF description: <<<<<<
CTEQ6.1
Reference:
J. Pumplin, D.R. Stump, J. Huston, H.L. Lai
W.K. Tung, S. Kuhlmann, J. Owens
hep-ph/0303013
This set has 41 member PDF
mem=0 --> central value (cteq61m)
mem=1-40 --> 20 sets of +ve/-ve error values
>>>>>> <<<<<<
-----------------------------------------------------------
This is the PDFevln package
Written by Gavin P. Salam (2001-2006)
It is made available under the GNU public license,
with the additional restriction that if you use it or any
derivative of it then you should cite:
M. Dasgupta and G.P. Salam, Eur.Phys.J.C24:213-236,2002.
You are also encouraged to cite the original references,
for LO, NLO and NNLO splitting functions, the QCD
1, 2 and 3 loop beta functions and the coupling and
PDF mass threshold matching functions.
-----------------------------------------------------------
x = 0.1, Q = 30.
iflv lhapdf ourpdf PLO_conv_ourpdf PNLO_conv_ourpdf
-6 0.0000000 0.0000000 0.0000000 0.0000000
-5 0.0148786 0.0148821 0.0921542 0.1938882
-4 0.0314312 0.0314340 0.0528865 0.0249562
-3 0.0608825 0.0608848 -0.0095773 -0.2567813
-2 0.0885760 0.0885775 -0.0763528 -0.5440898
-1 0.1214880 0.1214896 -0.1300409 -0.8175595
0 0.9779542 0.9779997 -2.2731258 1.6135916
1 0.3832341 0.3832380 -0.3130459 -2.1597162
2 0.6185498 0.6185565 -0.2770019 -2.6512379
3 0.0608825 0.0608848 -0.0095773 -0.2567813
4 0.0314312 0.0314340 0.0528865 0.0249562
5 0.0148786 0.0148821 0.0921542 0.1938882
6 0.0000000 0.0000000 0.0000000 0.0000000

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