Charybdis is designed to simulate the production and decay of black holes in hadron collider experiments, according to theories with TeV-scale gravity and extra spatial dimensions. The production of the black hole is assumed to take place with a basically geometrical cross section. The decay then takes place via Hawking radiation using the D-dimensional grey-body factors.

If you use the code please reference

C.M. Harris, P. Richardson and B.R. Webber, CHARYBDIS: A Black Hole Event Generator, JHEP 0308:033, hep-ph/0307305, 2003;
C.M. Harris, P. Kanti, Hawking radiation from a (4+n)-dimensional black hole: Exact results for the Schwarzschild phase, JHEP 0310:014, hep-ph/0309054, 2003.

The first of these is available here as either postscript or html.

The generator itself only performs the production and decay of the black hole. It is interfaced, via the Les Houches accord, to either HERWIG or PYTHIA to perform the parton shower evolution of the partons produced in the decay and their hadronization.

NEW! The most recent version of the code is 1.003, which includes the Yoshino-Rychkov cross section enhancement factors, an optional new "boiling remnant" model, relabeling of the hard process as a black hole (in HERWIG only), compatibility with a range of Fortran 77 and 90 compilers, and changes so that the parameters can be reset in the main HERWIG or PYTHIA program.

As the code is designed to run with either HERWIG or PYTHIA there are a few things which need to be set up.

You should have the following code:

In addition to this you will also need a Les Houches accord compliant version of either HERWIG or PYTHIA with both the dummy Les Houches routines UPINIT and UPEVNT and the dummy PDFLIB subroutines PDFSET and STRUCTM deleted. For HERWIG the first Les Houches compliant version is HERWIG6.500, for PYTHIA you will need a version above 6.220.

In the Les Houches routines the beams are specified as follows:

Square brackets show the default values. In the HERWIG version, they are overwritten with the values deduced from the HERWIG parameters PART1,PART2 and PBEAM1,PBEAM2. However in the PYTHIA version they must be reset explicitly in COMMON/HEPRUP/ if changed.

The CHARYBDIS parameters available to the user are as follows. Their default values are set in charybdis1003.F; any of them can be changed in the main program, as shown in the samples mainpythia.f and mainherwig.f.

In the Makefile you must specify which general purpose event generator, i.e.

whether or not you want PDFLIB You must also specify the name of the HERWIG/PYTHIA source and the location of the PDFLIB library.

If you extract the code to run it separately then the following should be taken into account.

In the HERWIG version the black hole entry in the event record has been assigned the provisional PDG code IDHEP=40 with name 'BlacHole'. However this has not been implemented in the PYTHIA version.

Chris Harris, Peter Richardson and Bryan Webber
Last modified: Fri Aug 25 13:49:54 BST 2006