5,289 research outputs found
Pomeron intercepts at colliders
A method allowing for a direct comparison of data with theoretical
predictions is proposed for forward jet production at HERA and Mueller-Navelet
jets at Tevatron and LHC. An application to the determination of the effective
Pomeron intercept in the BFKL-LO parametrization from d sigma/dx data at HERA
leads to a good fit with a significantly higher effective intercept, than for proton (total and
diffractive) structure functions. It is however less than the value of the
pomeron intercept using dijets with large rapidity intervals obtained at
Tevatron. We also evaluate the rapidity veto contribution to the higher order
BFKL corrections. We suggest to measure the dependence of the dijet
cross-sections as a function of the jet transverse energies as a signal for
BFKL pomeron at LHC.Comment: 10 pages, workshop on physics at lhc, similar to hep-ph/0002057,
completed for lh
The Diffractive Interactions Working Group Summary
Diffractive interactions represent a lively domain of investigations, as
confirmed by the progresses reported during the conference. We summarize the
diffractive interactions session and put the new experimental data (section 1),
developments in modeling diffraction (section 2) and the theoretical relations
with Quantum Chromodynamics (section 3) in perspective.Comment: Summary report at DIS200
Threshold scans in Central Diffraction at the LHC
We propose a new set of measurements which can be performed at the LHC using
roman pot detectors. The method exploits excitation curves in central
diffractive pair production, and is illustrated using the examples of the W
boson and top quark mass measurements. Further applications are mentioned.Comment: 11 page
Summary of Working Group I: Hadron Structure
A summary is given on the main aspects which were discussed by the working
group. They include new results on the deep inelastic scattering structure
functions and and their parametrizations, the
measurement of the gluon density, recent theoretical work on the small
behavior of structure functions, theoretical and experimental results on
, the direct photon cross section, and a discussion of the event
rates in the high range at Tevatron and the high range at HERA, as
well as possible interpretations.Comment: 22 pages latex, including 8 figures (ps,eps), to appear in the
Proceedings of the International Conference on Deep Inelastic Scattering,
Chicago, April 1997, AI
Gaps between jets in double-Pomeron-exchange processes at the LHC
The possibility to measure jet-gap-jet final states in
double-Pomeron-exchange events at the LHC is presented. In the context of the
ATLAS experiment with additional forward physics detectors, cross sections for
different experimental settings and gap definitions are estimated. This is done
in the framework of the Forward Physics Monte Carlo interfaced with a
perturbative QCD model that successfully reproduces standard jet-gap-jet cross
sections at the Tevatron. The extrapolation to LHC energies follows from the
Balitsky-Fadin-Kuraev-Lipatov dynamics, implemented in the model at
next-to-leading logarithmic accuracy.Comment: 8 pages, 5 figures, version to appear in PR
Uncertainties on exclusive diffractive Higgs and jets production at the LHC
Two theoretical descriptions of exclusive diffractive jets and Higgs
production at the LHC were implemented into the FPMC generator: the Khoze,
Martin, Ryskin model and the Cudell, Hern\'andez, Ivanov, Dechambre exclusive
model. We then study the uncertainties. We compare their predictions to the CDF
measurement and discuss the possibility of constraining the exclusive Higgs
production at the LHC with early measurements of exclusive jets. We show that
the present theoretical uncertainties can be reduced with such data by a factor
of 5
Decisive test for the Pomeron at Tevatron
We propose a new measurement to be performed at the Tevatron which can be
decisive to distinguish between Pomeron-based and soft color interaction models
of hard diffractive scattering.Comment: 5 pages, 3 figures, 1 tabel revtex forma
Hard diffraction and the nature of the Pomeron
We ask the question whether the quark and gluon distributions in the Pomeron
obtained from QCD fits to hard diffraction processes at HERA can be dynamically
generated from a state made of ``valence-like'' gluons and sea quarks as input.
By a method combining backward Q^2-evolution for data exploration and forward
Q^2-evolution for a best fit determination, we find that the diffractive
structure functions published by the H1 collaboration at HERA can be described
by a simple ``valence-like'' input at an initial scale of order mu^2 ~ 2.3-2.7
GeV^2. The parton number sum rules at the initial scale mu^2 for the H1 fit
gives 2.1\pm .1\pm .1 and .13\pm .01 \pm .02 for gluon and sea quarks
respectively, corresponding to an initial Pomeron state made of (almost) only
two gluons. It has flat gluon density leading to a plausible interpretation in
terms of a gluonium state.Comment: 14 pages, 9 figure
Diffractive Production at the Tevatron and the LHC
We present predictions for the diffractive production of mesons in the
central rapidity region usually covered by collider detectors. The predicted
cross sections are based on the Bialas-Landshoff formalism for both exclusive
and inclusive production and makes use of the DPEMC Monte-Carlo simulation
adapted with kinematics appropriate for small-mass diffractive production. We
compare generator-level results with a CDF measurement for exclusive
production, and study background and other scenarios including the contribution
of inclusive production. The results agree with the Tevatron data and
are extrapolated, highlighting the exclusive \chic production at LHC
energies. A possible new measurement at the Tevatron using the D{\O}forward
detectors is investigated, taking advantage of the dominance of exclusive
production for high enough diffractive mass fraction.Comment: 9 pages, 2 figures, added akcnowledgment
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