Observation of proton-tagged, central (semi)exclusive production of high-mass lepton pairs in pp collisions at 13 TeV with the CMS-TOTEM precision proton spectrometer

Understand

The process pp$\to\ell^+\ell^-$p$^{(*)}$, with $\ell^+\ell^-$ a muon or an electron pair produced at midrapidity with mass larger than 110 GeV, has been observed for the first time at the LHC in pp collisions at $\sqrt{s} =$ 13 TeV.

• One of the two scattered protons is measured in the CMS-TOTEM precision proton spectrometer (CT-PPS), which operated for the first time in 2016.
• The second proton either remains intact or is excited and then dissociates into a low-mass state p$^{*}$, which is undetected.
• The measurement is based on an integrated luminosity of 9.4 fb$^{-1}$ collected during standard, high-luminosity LHC operation.