Measurement of the diffractive cross section in deep inelastic scattering using ZEUS 1994 data |
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| Authors: | J. Breitweg et al. |
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| Affiliation: | Argonne National Laboratory, Argonne, IL, USA, US
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| Abstract: | The DIS diffractive cross section, dsdiffg* p ? XN/dMXdsigma^{di!f!f}_{gamma^* p to XN}/dM_X, has been measured in the mass range MX < 15M_X < 15 GeV for g*pgamma^*p c.m. energies 60 < W < 20060 < W < 200 GeV and photon virtualities Q2 = 7Q^2 = 7 to 140 GeV2^2. For fixed Q2Q^2 and MXM_X, the diffractive cross section rises rapidly with WW, dsdiffg*p ? XN(MX,W,Q2)/dMX μ Wadiffdsigma^{di!f!f}_{gamma^*p to XN}(M_X,W,Q^2)/dM_X propto W^{a^{diff}} with adiff = 0.507 ±0.034 (stat)+0.155-0.046(syst)a^{diff} = 0.507 pm 0.034 (stat)^{+0.155}_{-0.046}(syst) corresponding to a t-averaged pomeron trajectory of [`( amathbb P )] = 1.127 ±0.009 (stat)+0.039-0.012 (syst)overline{ alpha_{_{{mathbb P}}} } = 1.127 pm 0.009 (stat)^{+0.039}_{-0.012} (syst) which is larger than [`( amathbb P )]overline{ alpha_{_{{mathbb 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)2F^{D(3)}_2 factorizes according to xmathbb P FD(3)2 (xmathbb P,b,Q2) = (x0/ xmathbb P)n FD(2)2(b,Q2)x_{_{{mathbb P}}} F^{D(3)}_2 (x_{_{{mathbb P}}},beta,Q^2) = (x_0/ x_{_{{mathbb P}}})^n F^{D(2)}_2(beta,Q^2). They are also consistent with QCD based models which incorporate factorization breaking. The rise of xmathbb P FD(3)2x_{_{{mathbb P}}} F^{D(3)}_2 with decreasing xmathbb Px_{_{{mathbb P}}} and the weak dependence of FD(2)2F^{D(2)}_2 on Q2Q^2 suggest a substantial contribution from partonic interactions. |
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