Comparison of $pp$ and $p\bar{p}$ differential elastic cross sections and observation of colourless C-odd gluonic exchanges

TL;DR

This paper presents evidence for the odderon, a C-odd gluonic exchange, by comparing elastic scattering data from proton-proton and proton-antiproton collisions across multiple energies, leading to the first observation of this phenomenon.

Contribution

It provides the first experimental evidence for the odderon by combining differential cross section measurements and extrapolations from different experiments and energies.

Findings

Significant difference between pp and p̄p elastic cross sections at 1.96 TeV.

Observation of C-odd gluonic exchanges (odderon) with over 5σ significance.

First experimental evidence supporting the existence of the odderon.

Abstract

The TOTEM 2.76, 7, 8, and 13 TeV pp elastic differential cross sections are extrapolated using a data-driven approach to obtain the 1.96 TeV pp elastic cross section. A difference with a 3.4$\sigma$ significance is observed between the extrapolated pp elastic cross section and the D0 p$\bar{\rm p}$ elastic cross section at 1.96 TeV in the region of the diffractive minimum and the second maximum of the pp cross section, providing evidence for colourless C-odd gluonic exchanges, also denoted as odderon. These results are combined with a TOTEM analysis of the same $t$-channel C-odd exchanges based on forward pp elastic scattering at TeV scale. The combined significance is larger than 5$\sigma$ and is interpreted as the first observation of odderon exchange.