Central Pseudorapidity Gaps in Events with a Leading Antiproton at the Fermilab Tevatron pbar-p Collider

Abstract

We report a measurement of the fraction of events with a large pseudorapidity gap $\Delta \eta$ within the pseudorapidity region available to the proton dissociation products $X$ in $\bar{p}+p\to \bar{p}+X$. For a final state $\bar{p}$ of fractional momentum loss ${\xi }_{\bar{p}}$ and 4-momentum transfer squared $t_{\bar{p}}$ within $0.06<{\xi }_{\bar{p}}<0.09$ and $|t_{\bar{p}}|<1.0$ [0.2] GeV${}^2$ at $\sqrt{s}=1800$ [630] GeV, the fraction of events with $\Delta \eta >3$is found to be $0.246\pm 0.001(\mathrm{stat})\pm 0.042(\mathrm{syst})$ [$0.184\pm 0.001(\mathrm{stat})\pm 0.043(\mathrm{syst})$]. Our results are compared with gap fractions measured in minimum bias $\bar{p}p$ collisions and with theoretical expectations.

7 pages, 4 figures, Submitted to Phys. Rev. Letters