Springer : Elastic differential cross-section measurement at $sqrt{s}=13$ TeV by TOTEM

The TOTEM collaboration has measured the elastic proton-proton differential cross section $$\mathrm{d}\sigma /\mathrm{d}t$$ at $$\sqrt{s}=13$$ TeV LHC energy using dedicated $$\beta ^{*}=90$$ m beam optics. The Roman Pot detectors were inserted to 10$$\sigma $$ distance from the LHC beam, which allowed the measurement of the range [0.04 GeV$$^{2}$$; 4 GeV$$^{2}$$ $$]$$ in four-momentum transfer squared |t|. The efficient data acquisition allowed to collect about 10$$^{9}$$ elastic events to precisely measure the differential cross-section including the diffractive minimum (dip), the subsequent maximum (bump) and the large-|t| tail. The average nuclear slope has been found to be $$B=(20.40 \pm 0.002^{\mathrm{stat}} \pm 0.01^{\mathrm{syst}})~$$GeV$$^{-2}$$ in the |t|-range 0.04–0.2 GeV$$^{2}$$. The dip position is $$|t_{\mathrm{dip}}|=(0.47 \pm 0.004^{\mathrm{stat}} \pm 0.01^{\mathrm{syst}})~$$GeV$$^{2}$$. The differential cross section ratio at the bump vs. at the dip $$R=1.77\pm 0.01^{\mathrm{stat}}$$ has been measured with high precision. The series of TOTEM elastic pp measurements show that the dip is a permanent feature of the pp differential cross-section at the TeV scale.