Generalized parton distributions and rapidity gap survival in exclusive diffractive pp scattering
- School of Physics and Astronomy, Tel Aviv University, Tel Aviv 61390 (Israel)
We study rapidity gap survival (RGS) in the production of high-mass systems (H=dijet, heavy quarkonium, Higgs boson) in double-gap exclusive diffractive pp scattering, pp{yields}p+(gap)+H+(gap)+p. Our approach is based on the idea that hard and soft interactions are approximately independent because they proceed over widely different time and distance scales. We implement this idea in a partonic description of proton structure, which allows for a model-independent treatment of the interplay of hard and soft interactions. The high-mass system is produced in a hard scattering process with exchange of two gluons between the protons, whose amplitude is calculable in terms of the gluon generalized parton distribution (GPD), measured in exclusive ep scattering. The hard scattering process is modified by soft spectator interactions, which we calculate neglecting correlations between hard and soft interactions (independent interaction approximation). We obtain an analytic expression for the RGS probability in terms of the phenomenological pp elastic scattering amplitude, without reference to the eikonal approximation. Contributions from inelastic intermediate states are suppressed. The onset of the black-disk limit in pp scattering at TeV energies strongly suppresses diffraction at small impact parameters and is the main factor in determining the RGS probability. Correlations between hard and soft interactions (e.g. due to scattering from the long-range pion field of the proton or due to possible short-range transverse correlations between partons) further decrease the RGS probability. We also investigate the dependence of the diffractive cross section on the transverse momenta of the final-state protons ('diffraction pattern'). By measuring this dependence one can perform detailed tests of the interplay of hard and soft interactions and even extract information about the gluon GPD in the proton. Such studies appear to be feasible with the planned forward detectors at the Large Hadron Collider.
- OSTI ID:
- 21020056
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 75, Issue 5; Other Information: DOI: 10.1103/PhysRevD.75.054009; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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AMPLITUDES
CERN LHC
CORRELATIONS
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DIFFRACTION MODELS
DISTRIBUTION
EIKONAL APPROXIMATION
ELASTIC SCATTERING
GLUONS
HIGGS BOSONS
IMPACT PARAMETER
INTERMEDIATE STATE
JET MODEL
PARTICLE RAPIDITY
PIONS
PROBABILITY
PROTONS
QUARKONIUM
TEV RANGE
TRANSVERSE MOMENTUM