Measurement of differential cross sections for single diffractive dissociation in $\sqrt{s} = 8$ TeV $pp$ collisions using the ATLAS ALFA spectrometer

TL;DR

This paper measures the differential cross sections for single diffractive dissociation in proton-proton collisions at 8 TeV using the ATLAS ALFA spectrometer, providing insights into the underlying physics of diffraction and pomeron exchange.

Contribution

It presents the first detailed measurement of single diffractive dissociation cross sections at 8 TeV with the ATLAS ALFA detector, including the total and differential cross sections and pomeron intercept estimation.

Findings

Total cross section measured as 1.59 ± 0.13 mb.

Exponential t dependence with slope B = 7.65 ± 0.34 GeV^{-2}.

Pomeron intercept α(0) = 1.07 ± 0.09.

Abstract

A dedicated sample of Large Hadron Collider proton-proton collision data at centre-of-mass energy $\sqrt{s}=8$ TeV is used to study inclusive single diffractive dissociation, $pp \rightarrow Xp$. The intact final-state proton is reconstructed in the ATLAS ALFA forward spectrometer, while charged particles from the dissociated system $X$ are measured in the central detector components. The fiducial range of the measurement is $-4.0 < \log_{10} \xi < -1.6$ and $0.016 < |t| < 0.43 \ {\rm GeV^2}$, where $\xi$ is the proton fractional energy loss and $t$ is the squared four-momentum transfer. The total cross section integrated across the fiducial range is $1.59 \pm 0.13 \ {\rm mb}$. Cross sections are also measured differentially as functions of $\xi$, $t$, and $\Delta \eta$, a variable that characterises the rapidity gap separating the proton and the system $X$. The data are consistent with an exponential $t$ dependence, ${\rm d} \sigma / {\rm d} t \propto \text{e}^{Bt}$ with slope parameter $B = 7.65 \pm 0.34 \ {\rm GeV^{-2}}$. Interpreted in the framework of triple Regge phenomenology, the $\xi$ dependence leads to a pomeron intercept of $\alpha(0) = 1.07 \pm 0.09$.