Particle accelerators' search for nature's hidden dimensions comes up empty

It sounds like something that should be reported at the Onion, but here I am to tell you that the people who run the CMS detector at the LHC have just released their most recent results. Apparently, if there are extra dimensions, they haven't been hiding anywhere the LHC can find them. To add to the misery of extra dimension hunters, the data from Fermilab's D0 collaboration has also been used to not find extra dimensions.

No, seriously—with the LHC performing so well, the folks at CMS have a huge amount of data. And although the Tevatron is no more, the data remains, and the D0 folk have not been afraid to use it. Between the two of them, they have now eliminated a large range of possibilities when it comes to hidden dimensions, which puts some limits on the imagination of string theorists.

The two detector teams looked for the same signature of extra dimensions using the wave-like nature of particles. Every particle has a wavepacket, which is the wave-like nature of a particle that is confined by the particle's mass and motion to a region surrounding the particle's current location.

When a particle is confined in a box that has dimensions about the same size as its wavepacket, the reflections of the waves from the edges of the box will interfere. This interference pattern means that the particle will only be found in certain places and with certain energies.

If there are extra dimensions (such as in string theory and some other ideas), then the wavepacket should extend into those. If a dimension is curled up on itself, then it will act a bit like a box: any wavepacket that is longer than the dimension will also interfere with itself. Since the particle will only exist in places the wavepacket constructively interferes with itself, only certain particle masses are permitted.