The TOTEM experiment at the interaction point 5 of the LHC has measured the total, elastic and inelastic proton-proton cross sections in a centre-of-mass energy range from 2.76 to 13 TeV, mostly in dedicated fills with special beam optics.
Most recently, TOTEM has performed a series of detailed measurements at sqrt(s) = 13 TeV. Elastic scattering data in the Coulomb-nuclear interference region, at squared four-momentum transfers down to |t| ~ 8 x 10^{-4} GeV^{2} allowed the first measurement of the rho parameter at sqrt(s) = 13 TeV, where rho is the ratio between the real and the imaginary part of the nuclear elastic scattering amplitude at t = 0. This measurement, combined with the total cross-section results and with the earlier rho measurement at sqrt(s) = 8 TeV, is compatible with predictions of a colourless 3-gluon compound state (a.k.a. Odderon) exchange in the t-channel of proton-proton elastic scattering, as postulated by some theoretical models.
On the large |t| side the elastic differential cross-section measurement was pushed to 4 GeV^{2}. Thanks to very high statistics, the dip-bump structure between 0.4 and 0.8 GeV^{2} was surveyed with unprecedented precision. The presence of a dip in pp scattering in contrast to a shoulder in pbar-p scattering at Tevatron is another Odderon indication.
A brief second part of this seminar will be dedicated to prospects for central exclusive production measurements together with the CMS experiment. Pertinent data sets have been collected in 2015 and 2018. The analysis searching for glueball candidates is presently ongoing.
The presentation will close with an outlook on plans for LHC Run 3.
