Abstract
In a special run of the LHC with β = 2.5 km,
proton–proton elastic-scattering events were recorded at
√s = 13 TeV with an integrated luminosity of 340 µb−1
using the ALFA subdetector of ATLAS in 2016. The elastic cross section was measured differentially in the Mandelstam t variable in the range from −t = 2.5 · 10−4 GeV2
to −t = 0.46 GeV2 using 6.9 million elastic-scattering
candidates. This paper presents measurements of the total
cross section σtot, parameters of the nuclear slope, and the ρparameter defined as the ratio of the real part to the imaginary
part of the elastic-scattering amplitude in the limit t → 0.
These parameters are determined from a fit to the differential
elastic cross section using the optical theorem and different
parameterizations of the t-dependence. The results for σtot
and ρ are
σtot(pp → X) = 104.7 ± 1.1 mb, ρ = 0.098 ± 0.011.
The uncertainty in σtot is dominated by the luminosity measurement, and in ρ by imperfect knowledge of the detector
alignment and by modelling of the nuclear amplitude.
Science, Faculty of
TRIUMF
Non UBC
Physics and Astronomy, Department of
Reviewed
Faculty
Researcher