The first experimental observation of odderon exchange

Abstract

We describe an analysis comparing the ${\rm p}\bar{\rm p}$ elastic cross section as measured by the D0 Collaboration at a center-of-mass energy of 1.96 TeV to that in pp collisions as measured by the TOTEM Collaboration at 2.76, 7, 8, and 13 TeV using a data-driven approach. The TOTEM cross sections, extrapolated to a center-of-mass energy of $\sqrt{s}=1.96$~TeV, are compared with the D0 measurement in the region of the diffractive minimum and the second maximum of the pp cross section. The two data sets disagree at the 3.4$\sigma$ level and thus provide evidence for the t-channel exchange of a colorless, C-odd gluonic compound, also known as the odderon. We combine these results with a TOTEM analysis of the same C-odd exchange based on the total cross section and the ratio of the real to imaginary parts of the forward elastic strong interaction scattering amplitude in pp scattering for which the significance is between 3.4$\sigma$ and 4.6$\sigma$. The combined significance is larger than 5$\sigma$ and is interpreted as the first observation of the exchange of a colorless, C-odd gluonic compound.