[LHAPDF-announce] LHAPDF 6.0.0 final testing version available

[Andy Buckley]

Dear LHAPDF users,

We're pleased to announce that the final beta testing version of the
next generation version 6 of LHAPDF is now available to download and
test from the LHAPDF website, with documentation and code tarball at the
following URLs respectively:

http://lhapdf.hepforge.org/lhapdf6/
http://www.hepforge.org/downloads/lhapdf

This version has the following (selected!) features:

* PDF sets are now "just data", in a standardised plain text format --
PDF groups can release new PDFs without requiring an LHAPDF library update.

* The library contains standard implementations of PDF grid
interpolators (including flavour threshold effects) and alpha_s solvers.

* The restrictive memory problems of the Fortran version are all solved.
PDF objects are dynamically allocated, so the memory footprint is only
as big as what you use. A test loading of a 50 member PDF set now
requires ~20 MB, where previously 2 GB were required in full-memory mode!

* No restriction on the number of simultaneous PDF sets, and single PDF
members can also be loaded without needing to read or allocate the rest
of the set.

* As fast as LHAPDF5... and faster for loading single members from PDF
sets, cf. "normal" event generation.

* Completely general (and query-able) PDF parton content, using the PDG
ID code scheme.

* Fixes several fundamental bugs in LHAPDF5, particularly re. reporting
of set metadata and alpha_s values in multi-set mode.

* Powerful metadata system for PDF/set configuration and
"self-description"/"self-documentation".

* Fully object oriented C++ and Python interfaces, as well as the legacy
Fortran LHAPDF/PDFLIB style. The legacy interfaces no longer have a
number of simultaneous sets restriction, plus the other memory benefits,
but the new interface is much nicer for new/actively developed code!

We have migrated ~200 of the latest PDF sets from LHAPDF5 to the new
format: these are available from
http://www.hepforge.org/archive/lhapdf/pdfsets/6.0.0/ as tarballs which
can be expanded into the LHAPDF data directory (or any directory
mentioned in the colon-separated $LHAPDF_DATA_PATH environment
variable). The CT10nlo and CTEQ6L1 PDFs have been explicitly validated
as equivalent to their LHAPDF5 versions (except re. fixed
metadata/alpha_s behaviours) to less than 1/1000 fraction deviations...
usually _much_ less. Other sets will be validated (and re-migrated as
necessary) more gradually -- please let us know if you want a specific
set to be validated: until then it will remain in the "unvalidated"
directory on the downloads page and will print a warning message at runtime.

A test version of LHAPDF with the two validated PDF sets is installed
for the 64 bit Scientific Linux platform (cf. lxplus6) at
/afs/cern.ch/sw/lcg/experimental/lhapdf -- to use it, just source the
setup script in that directory. Here's an interactive demo with the
Python interface:

abuckley at lxplus0205:~$ source
/afs/cern.ch/sw/lcg/experimental/lhapdf/setup.sh
abuckley at lxplus0205:~$ python
Python 2.6.6 (r266:84292, Feb 22 2013, 14:54:23)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-3)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import lhapdf
>>> help(lhapdf)  # shows documentation
>>> p = lhapdf.mkPDF("CT10nlo", 0)
>>> p.xfxQ(21, 1e-4, 100)
85.051656245059974
>>> [p.xfxQ(id, 1e-4, 100) for id in range(-6,7)]
[0.0, 2.4333865198231006, 3.0477717380935694, 3.4319913024933939,
3.4995140331291843, 3.5032221055877923, 85.051656245059974,
3.5159562771911506, 3.5200820076592261, 3.4319913024933939,
3.0477717380935694, 2.4333865198231006, 0.0]
etc.

You will find extensive documentation on the LHAPDF6 website, linked
above. Please test this final pre-release version and let us know about
any problems you encounter, from the build system to the programming
interface, to the physics content! Our current plan is for the first
stable release of version 6 later this month, and the final release of
LHAPDF5 at the end of August, after which LHAPDF6 will be the only
actively maintained (and developed) version of the library. A
publication describing the new version will appear as soon as possible
after the stable release.

Best regards,
Andy, for the LHAPDF6 team

-- 
Dr Andy Buckley, Royal Society University Research Fellow
Particle Physics Expt Group, University of Edinburgh / PH Dept, CERN