Synopsis

# No Quantum Black Holes Detected at LHC

Physics 7, s28
An analysis of LHC particle collisions shows no evidence that so-called quantum black holes have been created to date.

We have gotten used to Einstein’s representation of spacetime, in which space and time are interwoven into a four-dimensional continuum. But according to certain quantum gravity theories, there may be some extra, hidden dimensions of space, curled up on a scale much smaller than a proton. In this case, theoretical calculations have suggested the Large Hadron Collider (LHC) could produce ephemeral objects called quantum black holes (QBHs) as it smashes particles together. Quantum-mechanical effects play an important role in these objects, making them decay instantly with no macroscopic consequences. The observation of such QBHs would thus call for a revision of our understanding of spacetime.

Now, as reported in Physical Review Letters, the collaboration running the LHC ATLAS detector—one of the two detectors involved in the discovery of the Higgs boson—has carried out an extensive search for QBHs by analyzing the full dataset of $8$-tera-electron-volt (TeV) proton-proton collisions that took place at the LHC in 2012. Had such QBHs been created, they would have decayed into various particles that could be seen with the ATLAS detectors. ATLAS looked for a specific set of predicted decay products: an electron or a muon and a quark jet. While the search came up empty, the analysis set a lower bound of $5$ TeV on the mass of QBHs, which may help guide future searches. Larger masses may be probed at the next, higher energy LHC run. – Matteo Rini

## Related Articles

Atomic and Molecular Physics

### Trapped Ions Go the Distance

Researchers have achieved long-distance entanglement between two calcium ions, each of which lies in a different building, showing that trapped ions could be used to create quantum networks. Read More »

Particles and Fields

### Probing Majorana Neutrinos

Detecting neutrinoless double-beta decay would confirm that the neutrino is its own antiparticle. Data from the KamLAND-Zen experiment contain no strong evidence of such events, constraining neutrino properties. Read More »

Chemical Physics

### Quantum Circuit Tackles “Diabolical” Photochemical Process

A quantum device shows promise for simulating molecular dynamics in a difficult-to-model photochemical process that is relevant to vision. Read More »