Evidence for non-exponential elastic proton-proton differential cross-section at low |t| and sqrt(s) = 8 TeV by TOTEM

Understand

The TOTEM experiment has made a precise measurement of the elastic proton-proton differential cross-section at the centre-of-mass energy sqrt(s) = 8 TeV based on a high-statistics data sample obtained with the beta* = 90 optics.

• Both the statistical and systematic uncertainties remain below 1%, except for the t-independent contribution from the overall normalisation.
• This unprecedented precision allows to exclude a purely exponential differential cross-section in the range of four-momentum transfer squared 0.027 < |t| < 0.2 GeV^2 with a significance greater than 7 sigma.
• Two extended parametrisations, with quadratic and cubic polynomials in the exponent, are shown to be well compatible with the data.