Measurements of diffractive dissociation cross sections in pp collisions at √s = 7 TeV are presented in kinematic regions defined by the masses MX and MY of the two final-state hadronic systems separated by the largest rapidity gap in the event. Differential cross sections are measured as a function of ξX = M2X/s in the region −5.5 < log10ξX < −2.5, for log10MY < 0.5, dominated by single dissociation (SD), and 0.5 < log10MY < 1.1, dominated by double dissociation (DD), where MX and MY are given in GeV. The inclusive pp cross section is also measured as a function of the width of the central pseudorapidity gap Δη for Δη > 3, log10MX > 1.1, and log10MY > 1.1, a region dominated by DD. The cross sections integrated over these regions are found to be, respectively, 2.99 ± 0.02 (stat)+0.32−0.29 (syst) mb, 1.18 ± 0.02(stat) ± 0.13 (syst) mb, and 0.58 ± 0.01(stat)+0.13−0.11 (syst) mb, and are used to extract extrapolated total SD and DD cross sections. In addition, the inclusive differential cross section, dσ/dΔηF, for events with a pseudorapidity gap adjacent to the edge of the detector, is measured over ΔηF = 8.4 units of pseudorapidity. The results are compared to those of other experiments and to theoretical predictions and found compatible with slowly rising diffractive cross sections as a function of center-of-mass energy.
- Cross section