Jet-gap-jet Analysis

The aim of this analysis is to study events with a rapidity gap between two high ET jets. These events were observed at Tevatron [1,2] and HERA [3,4,5] and can be described by the hard color singlet exchange in the BFKL framework [6].

Authors: Sheila Amaral, Alexander Proskuryakov


We present a study of dijet events, where the two highest ET jets are separated by a large gap in pseudo-rapidity, in pp collisions at √s = 10 TeV. We discuss the feasibility of observing this process with a integrated luminosity for single interactions of 1 pb-1 collected by the CMS detector in 2009 and 2010. The observation of the hard color-singlet exchange process in pp scattering at √s = 7 TeV is reported.

Schematic diagram of the elastic parton-parton scattering via Hard Color Singlet exchange

Tevatron Results

Gap fraction

PAS and Analysis Note:

  • Approval plan schedule: FWD-PAG Pre-approval NOT YET DEFINED.
  • PAS draft v0.0: link here


HARDCOL[7]: Hard Color Singlet exchange processes in PYTHIA

Original HARDCOL page

HARDCOL Interface

MC Samples

Sample MC Total # of evts Cross section Notes
p p → jet+gap+jet HARDCOL 3.6M 3.5E-03 mb CTEQ6L1 and 2→ 2 pT Min 40 GeV
QCD dijet PYTHIA 3.6M 3.5E-02 mb CTEQ6L1 and 2→ 2 pT Min 40 GeV

* assuming that Color Singlet cross section is 10% of QCD dijet (PYTHIA)

** Assumes S2 = 0.1


  • Diffractive dijets and other subjects meeting (04-Jun-2009): jet-gap-jet

  • Diffractive dijets and other subjects meeting (04-Jun-2009): jet-gap-jet



[1] D0 Collaboration, B Abbott et al., Phys. Lett. B440 (1998) 189.
[2] CDF Collaboration, F. Abe et al., Phys. Rev. Lett. 80 (1998) 1156.
[3] ZEUS Coll., M. Derrick et al., Phys. Lett. B369 55 (1996).
[4] H1 Coll., C. Adloff et al., Eur. Phys. J. C24, 517 (2002).
[5] ZEUS Coll., S. Chekanov et al. Eur. Phys. J. C50 (2007) 283-297.
[6] A.H. Mueller and W.-K. Tang, Phys. Lett. B284 (192) 123.
[7] R. Enberg, G. Ingelman, L. Motyka, Phys.Lett. B524 (2002) 273-282.

-- SheilaMaraSilvaDoAmaral - 2009-09-14

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