Speaker
Description
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. The total, elastic and inelastic proton-proton cross-sections were determined using the luminosity-independent method based on the optical theorem.
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 TOTEM total cross-section results, led to the exclusion of all the models classified and published by COMPETE. The rho and sigma_tot results obtained by TOTEM are compatible with
predictions of a colourless 3-gluon bound state exchange in the t-channel of proton-proton elastic scattering, as postulated by alternative theoretical models both in the Regge-like framework and in the modern QCD framework.
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. At
higher |t|-values up to the end of the observed range no further structure
is present.
The presentation will conclude with an outlook on measurements planned for LHC Run 3.
