  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.
