Production of rare particles within rapidity gaps has been proposed as a
background-free signal for the detection of new physics at hadron colliders. No
complete formalism accounts for such processes yet. We study a simple
lowest-order QCD model for their description. Concentrating on Higgs
production, we show that the calculation of the cross section pp -> pp H can be
embedded into existing models which successfully account for diffractive data.
We extend those models to take into account single and double diffractive cross
sections pp -> H X1 X2 with a gap between the fragments X1 and X2. Using
conservative scenarios, we evaluate the uncertainties in our calculation, and
study the dependence of the cross section on the gap width. We predict that
Higgs production within a gap of 4 units of rapidity is about 0.3 pb for a 100
GeV Higgs at the Tevatron, and almost 2 pb for a 400 GeV Higgs within a gap of
6 units at the LHC with 14 TeV beams.Comment: LaTeX file, 30 pages, 12 figures and psfig.sty included in a second
uufile. The full ready-to-print postscript manuscript is available by
anonymous ftp at ftp://lpsvsh.lps.umontreal.ca/ in theorie/hep-ph/Rapidity.ps
(it's a VAX so you'll have to use the format theorie.hep-ph if you change by
more than one directory at a time