gamma2MC version 1.1.1
A program to compute the di-photon cross section at Next-to-Leading order
(NLO) in QCD at hadronic colliders.
See Ref.  for details and results.
program the di-photon cross section, p p(bar) --> gamma gamma X, can be
computed through three distinct subprocesses:
Through the Higgs resonance: g g --> H X, followed by
H --> gamma gamma. The production cross section of the
Higgs boson is through gluon-gluon fusion (with all associated
channels at NLO) in the heavy top quark limit (top
quark mass dependence is included only in the LO prefactor). The
branching ratio to gamma gamma is not included. It
can be obtained elsewhere, such as from the program HDECAY .
Through the (formally NNLO) process g g --> gamma gamma X, which
occurs at one loop. This box contribution is then treated
as the LO part of a NLO calculation, where only
gluon-gluon initial-states are considered.
Through q qbar --> gamma gamma X , as well as all associated
channels through NLO. This process at NLO has a collinear
singularity when the photon and a final-state quark are
collinear. This singularity has been MSbar-subtracted, so
that the calculation should be finite for any isolation cuts.
However, no fragmentation processes are included, so only a
calculation with an IR-safe isolation (such as Frixione's
smooth isolation cut ) has any physical meaning at NLO.
(I.e, the calculation with the IR-safe isolation cut does
not depend on the subtraction prescription and does not get any
contribution from photon fragmentation processes.) A
complementary program that does contain fragmentation processes
in di-photon production is DIPHOX .
The source code can be obtained here:
Click here for the
installation guide .
Click here for the
program manual and input-file guide .
This introductory page, as well as the installation guide and program manual/input-file guide, is also included in the source code distribution.
The program uses the LHAPDF (Les Houches Accord PDF) interface to access various
up-to-date parton distribution function sets. More information on downloading
the LHAPDF libraries and the various PDF sets can be found at
Please send questions or comments to
gamma2MC_1.1.1: Increased compiler optimization to cure instabilities at very high statistics. (Current version)
gamma2MC_1.1: Updated to use LHAPDFs.
Z. Bern, L. Dixon, and C. Schmidt,
Phys. Rev. D66 (2002) 074018.
A. Djouadi, J. Kalinowski and M. Spira
Comput. Phys. Commun. 108 (1998) 56.
Phys. Lett. B429 (1998) 369.
T. Binoth, J.P. Guillet, E. Pilon and M. Werlen,
Eur. Phys. J. C16 (2000) 311.