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1.
In this study,we obtain the universal function corresponding to the diffractive process and show that the cross section exhibits geometrical scaling.It is observed that diffractive theory according to the color dipole approach at small-x is a convenient framework that reveals the color transparency and saturation phenomena.We also calculate the contribution of heavy quark production in the diffractive cross section at high energy that is determined by the small size dipole configuration.The ratio of the diffractive cross section to the total cross section in electron-proton collision is the other important quantity that is computed in this work. 相似文献
2.
R. Engel D.Y. Ivanov R. Kirschner L. Szymanowski 《The European Physical Journal C - Particles and Fields》1998,4(1):93-99
We calculate the cross section of diffractive charge-parity neutral meson production in virtual photon proton collision at high energies. Due to the opposite -parities of photon and meson () this process probes the -channel odderon exchange which is described here as noninteracting three–gluon exchange. Estimates for the cross section of inelastic
diffractive process are presented. The total cross section of diffractive meson photoproduction is found to be 47 pb. The cross sections for the diffractive production of light mesons () in collisions are of the same order if the photon virtuality is .
Received: 30 July 1997 相似文献
3.
Data on diffractive photoproduction of isoscalar states appear to be anomalously large in a number of channels. Isoscalar diffractive photoproduction is studied in a model in which the pomeron is approximated by two gluons, and in which gluon intermediate states are allowed in the pomeron-meson interaction. It is shown that the model allows a resolution of the long-standing problem of the small (in vector meson dominance terms) diffractive θ photoproduction cross section. This sets the scale for the calculation, and it is then demonstrated that the model can explain the large isoscalar cross section if it is due primarily to the diffractive photoproduction of a system of gluons. 相似文献
4.
《The European Physical Journal C - Particles and Fields》2007,50(1):1-20
Measurements are presented of diffractive open charm production at HERA. The event topology is given by ep→eXY where the system
X contains at least one charmed hadron and is well separated by a large rapidity gap from a leading low-mass proton remnant
system Y. Two analysis techniques are used for the cross section measurements. In the first, the charm quark is tagged by
the reconstruction of a D*±(2010) meson. This technique is used in deep-inelastic scattering (DIS) and photoproduction (γp). In the second, a method
based on the displacement of tracks from the primary vertex is used to measure the open charm contribution to the inclusive
diffractive cross section in DIS. The measurements are compared with next-to-leading order QCD predictions based on diffractive
parton density functions previously obtained from a QCD analysis of the inclusive diffractive cross section at H1. A good
agreement is observed in the full kinematic regime, which supports the validity of QCD factorization for open charm production
in diffractive DIS and γp. 相似文献
5.
J. Bartels H. Jung M. Wüsthoff 《The European Physical Journal C - Particles and Fields》1999,11(1):111-125
We study the diffractive production of jets with large transverse momenta in the region of large diffractive masses (small ). Cross sections for transverse and longitudinal photons are obtained in the leading log and log approximation, keeping all powers in log . We perform a numerical study and illustrate the angular distribution of the three jets. We also estimate the integrated
diffractive three jet cross section and compare with the dijet cross section obtained before.
Received: 11 March 1999 / Published online: 14 October 1999 相似文献
6.
The single diffractive component in hadronhadron interactions is studied in the two-component Dual Parton Model. We distinguish high mass single diffraction represented by a triple-Pomeron exchange and low mass single diffraction described via a two channel eikonal method. The calculated single diffractive cross sections, and the distributions agree quite well with data from collider and fixed target experiments. The fit of the model parameters to cross section data gives a extrapolation of the total, elastic, and single diffractive cross sections to supercollider energies which depends on the parton structure functions used for the minijet component. 相似文献
7.
8.
《The European Physical Journal C - Particles and Fields》2007,51(3):549-568
Measurements are presented of differential dijet cross sections in diffractive photoproduction (Q2<0.01 GeV2) and deep-inelastic scattering processes (DIS, 4<Q2<80 GeV2). The event topology is given by ep→eXY, in which the system X, containing at least two jets, is separated from a leading
low-mass baryonic system Y by a large rapidity gap. The dijet cross sections are compared with NLO QCD predictions based on
diffractive parton densities previously obtained from a QCD analysis of inclusive diffractive DIS cross sections by H1. In
DIS, the dijet data are well described, supporting the validity of QCD factorisation. The diffractive DIS dijet data are more
sensitive to the diffractive gluon density at high fractional parton momentum than the measurements of inclusive diffractive
DIS. In photoproduction, the predicted dijet cross section has to be multiplied by a factor of approximately 0.5 for both
direct and resolved photon interactions to describe the measurements. The ratio of measured dijet cross section to NLO prediction
in photoproduction is a factor 0.5±0.1 smaller than the same ratio in DIS. This suppression is the first clear observation
of QCD hard scattering factorisation breaking at HERA. The measurements are also compared to the two soft colour neutralisation
models SCI and GAL. The SCI model describes diffractive dijet production in DIS but not in photoproduction. The GAL model
fails in both kinematic regions. 相似文献
9.
The pomeron-particle total cross section and diffractive production of showers at very high energies
The experimental data of ISR and NAL for the process pp → pX are used for the determination of the pomeron-particle total cross section and the triple-pomeron vertex. Estimates of the cross sections of the diffractive production of one and several showers of particles are given. It is shown that at s ~ 103 GeV2 the cross section of all inelastic diffractive processes is ~ 6 mb and grows with energy. A theoretical estimate of the amplitude of pomeron-pomeron scattering is given. 相似文献
10.
Improved possibilities to find the Higgs boson in diffractive events, having less hadronic activity, depend on whether the cross section is large enough. Based on the soft color interaction models that successfully describe diffractive hard scattering at DESY HERA and the Fermilab Tevatron, we find that only a few diffractive Higgs events may be produced at the Tevatron, but we predict a substantial rate at the CERN Large Hadron Collider. 相似文献
11.
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13.
The double diffractive J/ψ, hard production processes is discussed. Assuming that Pomeron has parton distributions and dominated by gluons with behavior as 1/x when x is small, the energy dependance of the cross section, for above processes is calculated and compared with both the cross section of single diffractive hard scattering and of Drell-Yan processes . It is shown that the is similar with and increases as (lnS)2 at superhigh energies. It is emphasized that this character may provide a new method for detecting physical particles at energy ranges of SSC. 相似文献
14.
We determine running coupling corrections to the kernel of the non-linear evolution equation for the cross section of single diffractive dissociation in high energy DIS. The running coupling kernel for diffractive evolution is found to be exactly the same as the kernel of the rcBK evolution equation. 相似文献
15.
The idea that the pomeron has partonic structure similar to any other hadron has been given strong support by recent measurements of the diffractive structure function at HERA. We present a detailed theoretical analysis of the diffractive structure function under the assumption that the diffractive cross section can be factorized into a pomeron emission factor and the deep inelastic scattering cross section of the pomeron. We pay particular attention to the kinematic correlations implied by this picture, and suggest the measurement of an angular correlation which should provide a first test of the whole picture. We also present two simple phenomenological models for the quark and gluon structure of the pomeron, which are consistent with various theoretical ideas and which give equally good fits to recent measurements by the H1 collaboration, when combined with the pomeron emission factor of Donnachie and Landshoff. We predict that a large fraction of diffractive deep inelastic events will contain charm, and discuss how improved data will be able to distinguish the models. 相似文献
16.
I. Akushevich 《The European Physical Journal C - Particles and Fields》1999,8(3):457-463
The electromagnetic radiative correction to the cross section of the vector meson electroproduction is calculated. Explicit
covariant formulae for the observed cross section are obtained. The dependence of the radiative correction on the experimental
resolution and on the inelasticity cut is discussed. The FORTRAN code DIFFRAD, based on both exact (ultrarelativistic) and
approximate sets of the formulae for the radiative correction to the cross section, is presented. Detailed numerical analysis
for kinematical conditions of the recent experiments on the diffractive electroproduction of vector mesons is given.
Received: 23 August 1998 / Published online: 15 April 1999 相似文献
17.
Multihadron production at high energies proceeds through two mechanisms: A nondiffractive mechanism of a general multiperipheral nature and a diffractive mechanism. Assuming that the diffractive mechanism is dominated at present energies (s < 3000 BeV2) by single diffraction excitation we explore its theoretical and phenomenological implications. In particular we study the question of the rising total cross section. We show that “high mass diffraction excitation” leads to the formation of a central plateau in the inclusive single pion distribution and that the height of this plateau rises with energy and obeys scaling when normalized by the total cross section. We compute the multiplicity distribution for the diffractive component, and deduce the properties of the average multiplicity, its moments, and the statistical mechanics analogue of the “diffractive” Feynman gas. Two-particle correlations are computed and shown to be of a long range nature. Finally we outline an “improved” two component model into which some of the detailed features of the diffractive part are incorporated. 相似文献
18.
S. Bondarenko E. Levin J. Nuiri 《The European Physical Journal C - Particles and Fields》2002,25(2):277-286
We use the constituent quark model (CQM) to describe CDF data on double parton cross section and HERA data on the ratio cross section of elastic and inelastic diffractive productions. Our estimate shows that the radius of the constituent
quark turns out to be rather small, GeV-2, in accordance with the assumption on which CQM is based.
Received: 14 April 2002 / Published online: 9 August 2002 相似文献
19.
Charles Chiu 《Physics letters. [Part B]》1984,142(4):309-314
Although a substantial difference between pp differential cross section at ISR energies and differential cross section at SPS energy has been reported, we demonstrate that both differential cross sections, at least up to |t| ~ 1.2 GeV2, can be satisfactory accounted for within the usual eikonal model in which the diffractive component is crossing even. Thus at a given ultra high energy, there is no suggestive evidence for a difference between pp and diffractive peaks. 相似文献
20.
G. Veneziano 《Physics letters. [Part B]》1973,43(5):413-416
Assuming that the non diffractive part of exclusive cross sections contributes to the Pomeranchuk singularity in the total cross section, we derive general relations between Regge intercepts and parameters of the multiplicity distribution. A dynamical assumption on the mechanism that generates the Pomeron gives automatically an intercept near one provided that a particular correlation parameter is small. 相似文献