# Elastic differential cross-section ${\rm d}\sigma/{\rm d}t$ at $\sqrt{s}=$2.76 TeV and implications on the existence of a colourless 3-gluon bound state

## TL;DR

This paper reports precise measurements of the elastic proton-proton differential cross-section at 2.76 TeV, revealing features like a dip and bump, and discusses implications for a possible colourless 3-gluon bound state exchange.

## Contribution

The study provides the first detailed measurement of ${
m d}\sigma/{
m d}t$ at 2.76 TeV and suggests evidence for a colourless 3-gluon bound state in proton-proton scattering.

## Key findings

- Observation of a dip at |t|=0.61 GeV^2
- Ratio of bump to dip cross-sections is 1.7±0.2
- Significant difference compared to par{p} data at 1.96 TeV

## Abstract

The proton-proton elastic differential cross section ${\rm d}\sigma/{\rm d}t$ has been measured by the TOTEM experiment at $\sqrt{s}=2.76$ TeV energy with $\beta^{*}=11$ m beam optics. The Roman Pots were inserted to 13 times the transverse beam size from the beam, which allowed to measure the differential cross-section of elastic scattering in a range of the squared four-momentum transfer ($|t|$) from $0.36$ GeV$^{2}$ to $0.74$ GeV$^{2}$. The differential cross-section can be described with an exponential in the $|t|$-range between $0.36$ GeV$^{2}$ and $0.54$ GeV$^{2}$, followed by a diffractive minimum (dip) at $|t_{\rm dip}| = 0.61 \pm 0.03$ GeV$^{2}$ and a subsequent maximum (bump). The ratio of the ${\rm d}\sigma/{\rm d}t$ at the bump and at the dip is $1.7\pm 0.2$. When compared to the $\rm p\bar{p}$ measurement of the D0 experiment at $\sqrt s = 1.96$ TeV, a significant difference can be observed. Under the condition that the effects due to the energy difference between TOTEM and D0 can be neglected, the result provides evidence for a colourless 3-gluon bound state exchange in the $t$-channel of the proton-proton elastic scattering.