This market will resolve YES if any inelastic scattering process (particle creation or annihilation) involving a graviton is observed. The process need not be on-shell. It will resolve to 2060 if that year comes without any detection.

Background

Gravitons, as quantum particles, are believed to scatter not only with ordinary matter, but also with each other.

Scattering processes are termed inelastic if the nature of the particles themselves is changed. A classic example is electron-positron annihilation, in which two (or more) photons are produced:

This diagram can be read "backwards" as well: two photons scattering, and creating an electron-positron pair.

Replacing the photon with a graviton, two possibilities suggest themselves:

• Two (or more) high-energy gravitons annihilating, creating matter.

• A particle-antiparticle pair annihilating and dumping some of their energy into (on-shell) gravitons.

Here's another Feynman diagram, with time now going from left to right (yeah, I'm just ripping these all from wikipedia):

Here, an electron and a positron annihilate and create a photon, which then decays once again into an electron-positron pair. The intermediate photon is referred to as off-shell. For our purposes here, you may assume that that translates to "is present neither at the beginning nor the end of the scattering process". (It has a technical definition which is the same in practice.)

In light of this diagram, we add one more possibility for scattering processes involving gravitons: two particles interact, produce one more more off-shell gravitons (potentially in addition to other off-shell particles), and then the whole system again decays into ordinary matter.

This market is about all of these types of processes. Experimental evidence for any quantum process involving a graviton will count towards a YES resolution.

These processes are difficult to detect, because the gravitational field is very weakly coupled to ordinary matter. I know of no current experiments, even in the planning stages, that are expected to result in a YES resolution.

Detailed resolution criteria

This market may be a tricky one to resolve, so I will not be betting, at least until I come up with sufficiently unambiguous resolution criteria (which will probably never happen). Indirect detection will count towards a YES resolution if the overwhelming consensus among physicists is that it's an unambiguous signal.

In the event that it becomes "clear" (according to my conservative judgement) that the graviton-graviton cross section is exactly 0 in our universe, this market will resolve N/A, rather than to 2060.