Seminario Generale INFN

The unprecedented energy of proton proton collisions in the LHC gives the unique opportunity to probe deeper the details of nucleon-nucleon interaction. In a series of special runs with dedicated accelerator optics settings, the TOTEM experiment has been able to study the proton-proton nuclear interaction for the full set of LHC energies, and in a broad range of the 4-momentum transfer squared t, down to extremely small values (t < 10–3 GeV2), where perturbative QCD methods cannot be employed. In this seminar, the full suite of TOTEM measurements of elastic and total proton-proton cross section will be presented. In particular, recent results in the very low t region will be discussed, where the interference between nuclear and Coulomb interaction has allowed precision measurements of the ratio ρ of the real to imaginary part of the forward nuclear amplitude and has lead to a possible first evidence of the presence of an odd-signature component, the so-called Odderon. Finally, an overview of the ongoing physics program of the joint CMS-TOTEM Precision Proton Spectrometer (PPS) will be presented, with prospects for future measurements.