Measurement of differential cross sections for Single Diffractive Dissociation in $\sqrt{s} = 8$ TeV pp collisions using the ATLAS detector

Preliminary LHC results on proton tagged measurements of Single Diffractive Dissociation ($pp\rightarrow pX$) are presented from ATLAS using $\sqrt{s} = 8$ TeV data. The central ATLAS detector is used to reconstruct the dissociative $X$ system and the forward spectrometer ALFA is used to tag the intact proton. Differential cross sections are measured as a function of: $\xi$, the fractional energy loss of the intact proton; $|t|$, the squared four momenta exchanged and $\Delta\eta$, the observable rapidity gap. The unfolded $t$ differential cross section is consistent with an exponential dependence $d\sigma / dt \propto e^{Bt}$ with a slope parameter $B = 7.60 \pm 0.32 \textrm{GeV}^{-2}$. The unfolded $\xi$ differential cross section is interpreted in the framework of Regge phenomenology to extract a Pomeron intercept of $\alpha(0) = 1.07 \pm 0.09$.