Version 1.1.2 includes all bugfixes for previous versions as well as new ones.

Sherpa 1.1.2

Version 1.1.2 includes all bugfixes for previous versions as well as new ones (see Changelog below).

Download of Sherpa 1.1.2

The Sherpa package and a short primer on how to get started, can be downloaded here:

A Changelog for important differences between the previous version and this version is provided below. If you would like to be kept up-to-date about new versions or important updates of Sherpa, please subscribe to our announcement mailing list.

:!: Please note that you still have to apply any patches provided below after unpacking the tarball.

Patches/known problems/known bugs/FAQs

  • When writing HepMC events, the particle IDs in PdfInfo? have to be PDG IDs, and not -6, ..., 0, ... +6. This is only relevant if the user has been using the PdfInfo? object, or if crashes appear when reading in event files. Fix: Apply patch file via patch -p0 < hepmc-pdfinfo.patch in the top level directory of your Sherpa installation and recompile with "TOOLS/makeinstall".
  • If explicit mixing of neutral mesons like the B has been turned on, warning messages about unexpected non-fragmentation blobs appear from Hadron_Decays. Fix: Apply patch file via patch -p0 < mixing.patch in the top level directory of your Sherpa installation and recompile with "TOOLS/makeinstall".
  • The size of the HepEvt? common block initialised by our Lund interface is 4000, but in LHC experiments the convention is 10000. Fix: Apply patch file via patch -p0 < hepevt10k.patch in the top level directory of your Sherpa installation and recompile with "TOOLS/makeinstall".
  • If Sherpa has been compiled in 32bit mode on a 64bit architecture, the "makelibs" script didn't remember this choice, such that it always tried to produce 64bit process libraries, which produced a crash when Sherpa loaded them. Fix: Apply patch file via patch -p0 < makelibs.patch in the top level directory of your Sherpa installation and recompile with "TOOLS/makeinstall -t".
  • When polarised initial state were considered a problem appeared during process generation and the compilation of libraries. To fix this just apply patch file via patch -p0 < beampol.patch in the top level directory of your Sherpa installation and recompile with "TOOLS/makeinstall".
  • A certain ordering of MSSM vertices of the type "sfermion-> anti-chargino fermion" was neglected leading to a failure when calculating corresponding decays or processes involving such vertices. To fix this just apply patch file via patch -p0 < susy_vertex.patch in the top level directory of your Sherpa installation and recompile with "TOOLS/makeinstall".
  • For some ADD processes the generation of process libraries failed, causing an abort. To fix this just apply patch file via patch -p0 < addfix.patch in the top level directory of your Sherpa installation and recompile with "TOOLS/makeinstall".
  • When writing events to native Sherpa output, the event weight was always written as 1. This only affects users who run in EVENT_GENERATION_MODE=Weighted or use Enhance_Factors in their processes setup, and write events using SHERPA_OUTPUT. Fix: Apply patch file via patch -p0 < sherpa-weight.patch in the top level directory of your Sherpa installation and recompile with "TOOLS/makeinstall".

Changelog

User Interface changes

  • None

Bugfixes

  • Hadron property overwriting from the run card or command line didn't work.
  • Fix for graviton mass distribution in ADD model.
  • Position of decay blobs was not filled.
  • Fix for decay treatment in processes with container-particles in the decay only.
  • Fix for stalling due to shower rejection in the Underlying Event (error message about "too many trials" from Phase_Space_Handler)
  • Fix for rare crashes with "corrupted double-linked list"
  • Fix in the locking mechanism of library loading (relevant if you saw crashes during intialization when running Sherpa on a batch system/GRID)

New features/Improvements

  • Improvements in LHAPDF handling:
    • For LHAPDF > 5.4.0 use their native fortran wrapper functions
    • For all versions use initpdfsetbyname instead of initpdfset such that the path to the PDFsets is determined by LHAPDF itself. This allows you for example to specify the path by the environment variable LHAPATH.
  • Make Sherpa relocatable by allowing SHERPA_INCLUDE_PATH, SHERPA_SHARE_PATH and SHERPA_LIBRARY_PATH to be overwritten by corresponding environment variables.
  • Improvements in the handling of user-added BSM models with additional massive vector bosons.
  • Improvements in HepMC interface:
    • Add output class for HepMC::IO_GenEvent format (parameter HEPMC2_GENEVENT_OUTPUT=<filename>).
    • Add units information and beam particles to the created HepMC::GenEvent.
    • Add event weight to GenEvent? (useful for EVENT_GENERATION_MODE=Weighted)
  • Compatibility with gcc 4.3.1
  • Resurrected the missing DeltaPhi? and DeltaR selectors
  • AHADIC: Improve form of non-perturbative &#945;<sub>s</sub> for splittings according to recent measurements.
  • HADRONS: Include form factors for weak hyperon decays.
  • Optional on-shell treatment of decays in the hard process.
  • Unitarization method for anomalous gauge couplings added (Nucl.Phys.B308:127,1988)
  • Slightly changed default values for XS_REGULATION and SCALE_MIN in the underlying event setup to account for changes in hadronisation model.

Remarks

For process declarations a specific ordering is needed:

  • For electron-photon collisions make sure the photon is on the first beam, bunch and parton!
  • For electron-proton collisions make sure the electron is on the first beam, bunch and parton!

A few non-standard setups are not working. Do not even try:

  • Parton shower in DIS--like situations, i.e. with only one incoming leg that showers.
  • Substructure of photons.
  • Laser backscattering beyond the region where CompAZ is valid (up to 500 GeV).