EPJ

2023 Impact factor 4.2
EPJ C - Particles and Fields
Particles and Fields

Eur. Phys. J. C 6, 43-66
DOI 10.1007/s100529801016

Measurement of the diffractive cross section
in deep inelastic scattering using ZEUS 1994 data

The ZEUS Collaboration
J.Breitweg et al.

Argonne National Laboratory, Argonne, IL, USA

Received: 9 July 1998 / Revised version: 6 August 1998 / Published online: 29 October 1998

Abstract
The DIS diffractive cross section, $d\sigma^{di\!f\!f}_{\gamma^* p \to XN}/dM_X$, has been measured in the mass range MX < 15 GeV for $\gamma^*p$ c.m. energies 60 < W < 200 GeV and photon virtualities Q2 = 7 to 140 GeV2. For fixed Q2 and MX, the diffractive cross section rises rapidly with W, $d\sigma^{di\!f\!f}_{\gamma^*p \to XN}(M_X,W,Q^2)/dM_X \propto W^{a^{diff}}$ with $a^{diff} = 0.507 \pm 0.034 (stat)^{+0.155}_{-0.046}(syst)$ corresponding to a t-averaged pomeron trajectory of $\overline{ \alpha_{_{{\rm P}}} } = 1.127 \pm 0.009 (stat)^{+0.039}_{-0.012} (syst)$ which is larger than $\overline{ \alpha_{_{{\rm P}}} }$ observed in hadron-hadron scattering. The W dependence of the diffractive cross section is found to be the same as that of the total cross section for scattering of virtual photons on protons. The data are consistent with the assumption that the diffractive structure function FD(3)2 factorizes according to $x_{_{{\rm P}}} F^{D(3)}_2 (x_{_{{\rm P}}},\beta,Q^2) = (x_0/ x_{_{{\rm P}}})^n F^{D(2)}_2(\beta,Q^2)$. They are also consistent with QCD based models which incorporate factorization breaking. The rise of $x_{_{{\rm P}}} F^{D(3)}_2$ with decreasing $x_{_{{\rm P}}}$ and the weak dependence of FD(2)2 on Q2 suggest a substantial contribution from partonic interactions.

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