Quark reshuffle mimics nuclear fusion

But practical applications are unlikely, owing to the fleeting existence of heavy quarks.

Rearrangement of heavy quarks during subatomic-particle collisions can release amounts of energy equivalent to those from nuclear fusion.

Baryons are subatomic particles made up of three quarks, which are among the fundamental components that comprise all matter. In early 2017, researchers working on the Large Hadron Collider at CERN, Europe’s particle-physics laboratory near Geneva in Switzerland, discovered the first baryon known to contain two of the heavy ‘charm’ flavour of quark. This finding implies that the two quarks have an extremely large binding energy of around 130 megaelectronvolts.

Marek Karliner at Tel Aviv University and Jonathan Rosner at the University of Chicago in Illinois calculate what would happen if two baryons, each containing one charm quark, were to collide and the charm quarks rearrange to form such a ‘double-charmed’ baryon. The reaction, they report, would release 12 megaelectronvolts of energy — a quark-level equivalent of the fusion that occurs between nuclei of the heavy hydrogen isotopes deuterium and tritium.

Fusion between the even-heavier ‘bottom’ quarks is expected to release an order of magnitude more energy. However, heavy quarks exist only fleetingly, making it tricky to foresee any practical applications, the authors say.