Behavior of the diffractive cross section in hadron-nucleus collisions

A phenomenological analysis of diffractive dissociation of nuclei in proton-nucleus and meson-nucleus collisions is presented. The theoretical approach employed here is able to take into account at once data of the HELIOS and EHS/NA22 collaborations that exhibit quite different atomic mass dependences. Possible extensions of this approach to hard diffraction in nuclear processes are also discussed.Comment: 5 pages, 2 figure

Regge Analysis of Diffractive and Leading Baryon Structure Functions from DIS

In this paper we present a combined analysis of the H1 data on leading baryon and diffractive structure functions from DIS, which are handled as two components of the same semi-inclusive process. The available structure function data are analyzed in a series of fits in which three main exchanges are taking into account: pomeron, reggeon and pion. For each of these contributions, Regge factorization of the correspondent structure function is assumed. By this procedure, we extract information about the interface between the diffractive, pomeron-dominated, region and the leading proton spectrum, which is mostly ruled by secondary exchanges. One of the main results is that the relative reggeon contribution to the semi-inclusive structure function is much smaller than the one obtained from a analysis of the diffractive structure function alone.Comment: ps file, 22 pages, 5 figures. Totally revised version with major changes, to appear in Physical Review

Diffractive production of dijets by double Pomeron exchange processes

A phenomenological description of diffractive dijet hadroproduction via double Pomeron exchange is presented. This description is based on a modified version of the Ingelman-Schlein model which includes the evolution of the Pomeron structure function and corrections regarding rapidity gap suppression effects. The same quark-dominant Pomeron structure function employed in a previous report to describe diffractive dijet and W production via single Pomeron processes is shown here to yield results consistent with the available data for double Pomeron processes as well.Comment: 4 pages, REVTEX4.

What do experimental data "say" about growth of hadronic total cross-section?

We reanalyse $\bar p p$ and $pp$ high energy data of the elastic scattering above $\sqrt{s}=5$ GeV on the total cross-section $\sigma_{tot}$ and on the forward $\rho$-ratio for various models of Pomeron, utilizing two methods. The first one is based on analytic amplitudes, the other one relies on assumptions for $\sigma_{tot}$ and on dispersion relation for $\rho$. We argue that it is not possible, from fitting only existing data for forward scattering, to select a definite asymptotic growth with the energy of $\sigma_{tot}$. We find equivalent fits to the data together with a logarithmic Pomeron giving a behavior $\sigma_{tot} \propto \ln ^\gamma s$, $\gamma\in [0.5,2.20]$ and with a supercritical Pomeron giving a behavior $\sigma_{tot} \propto s^\epsilon$, $\epsilon\in [0.01,0.10]$.Comment: LaTeX, 18 pages, 5 eps figures included, to be published in Il Nuovo Ciment

Multiple scattering effects in proton-nucleus collisions and the behavior of the total and partial inelasticities

A modified version of a multiple scattering model is applied to describe nuclear inclusive reactions of the type pA-->pX and investigate the behavior of the inelasticity in nuclear processes. The modifications are such that some recent developments in the Pomeron physics are incorporated into the new theoretical scheme. The particular attention paid to the diffractive region of the spectrum results in a very good description of the diffractive cross section in terms of the atomic mass. Another important outcome resulting from this analysis is the average total inelasticity whose atomic mass and energy dependences are shown to be in agreement with the available data. Moreover, the behavior of partial inelasticities in intranuclear collisions is also discussed. [S0556-2813(99)00907-3].60

Charged Particle Multiplicity in Diffractive Deep Inelastic Scattering

The recent data from H1 Collaboration on hadron multiplicity in diffractive DIS has been studied in the framework of perturbative QCD as a function of invariant diffractive mass. The formulas obtained explain the observed excess of particle production in diffractive DIS relative to that in DIS and $e^+e^-$ annihilation. It is shown that the results are sensitive to the quark--gluon structure of the Pomeron. Namely, the data say in favour of a super-hard gluon distribution at the initial scale.Comment: 12 pages, 3 figures; to be published in Phys. Rev.

Regge Analysis Of Diffractive And Leading Baryon Structure Functions From Deep Inelastic Scattering

In this paper we present a combined analysis of the H1 data on leading baryon and diffractive structure functions from DIS, which are handled as two components of the same semi-inclusive process. The available structure function data are analyzed in a series of fits in which three main exchanges are taken into account: the Pomeron, Reggeon, and pion. For each of these contributions, Regge factorization of the correspondent structure function is assumed. By this procedure, we extract information about the interface between the diffractive, Pomeron-dominated, region and the leading proton spectrum, which is mostly ruled by secondary exchanges. One of the main results is that the relative Reggeon contribution to the semi-inclusive structure function is much smaller than the one obtained from an analysis of the diffractive structure function alone.659 B9600619600610Ahmed, T., (1995) Phys. Lett. B, 348, p. 681Derrick, M., (1995) Z. Phys. C, 68, p. 569Adloff, C., (1999) Eur. Phys. J. C, 6, p. 587Cartiglia, N., hep-ph/9706416http://www-zeus.desy.de/publications.php3Collins, P.D.B., (1977) An Introduction to Regge Theory and High Energy Physics, , Cambridge University Press, Cambridge, EnglandBatista, M., Covolan, R.J.M., (1999) Phys. Rev. D, 59, p. 054006Szczurek, A., Nikolaev, N.N., Speth, J., (1998) Phys. Lett. B, 428, p. 383Adloff, C., (1997) Z. Phys. C, 76, p. 613Breitweg, J., (1998) Eur. Phys. J. C, 1, p. 81Ingelman, G., Schlein, P., (1985) Phys. Lett., 152 B, p. 256Covolan, R.J.M., Soares, M.S., (1998) Phys. Rev. D, 57, p. 180Alvero, L., (1999) Phys. Rev. D, 59, p. 074022McDermott, M.F., Briskin, G., (1996) Proceedings of the Workshop "Future Physics at HERA", , edited by G. Ingelman, A. De Roeck, and R. Klanner, DESY, Hamburg, hep-ph/9610245Covolan, R.J.M., Soares, M.S., (1999) Phys. Rev. D, 60, p. 054005Covolan, R.J.M., Soares, M.S., (2000) Phys. Rev. D, 61, pp. 019901EGolec-Biemat, K., Kwieciński, J., Szczurek, A., (1997) Phys. Rev. D, 56, p. 3955Botje, M.A.J., QCDNUM16: A fast QCD evolution program, , Zeus Note 97-066www-h1.desy.de/h1/www/h1work/fit/h1fit.tools.htmlRoyon, C., Schoeffel, L., Bartels, J., Jung, H., Peschanski, R., (2001) Phys. Rev. D, 63, p. 074004Covolan, R.J.M., Montanha, J., Goulianos, K., (1996) Phys. Lett. B, 389, p. 176Goulianos, K., Montanha, J., (1999) Phys. Rev. D, 59, p. 114017Glück, M., Reya, E., Vogt, A., (1992) Z. Phys. C, 53, p. 651Covolan, R.J.M., Montanha, J., Pontes, A.N., Soares, M.S., in preparationBreitweg, J., (1998) Eur. Phys. J. C, 5, p. 41Adloff, C., (1999) Eur. Phys. J. C, 6, p. 421(2001) Eur. Phys. J. C, 20, p. 2