A particle called meson f0(1710) is the elusive ‘glueball,’ an exotic particle composed of pure force, according to a team of physicists at the Technische Universität Wien in Vienna, Austria.
A glueball is made up purely of gluons. Image credit: TU Wien.
For years, physicists have been looking for hypothetical particles called glueballs, which are composed purely of gluons.
Glueballs are predicted to be unstable. They can only be detected indirectly, by analyzing their decay.
“In particle physics, every force is mediated by a special kind of force particle, and the force particle of the strong nuclear force is the gluon,” explained team member Prof. Anton Rebhan.
“Gluons can be seen as more complicated versions of the photon. The massless photons are responsible for the forces of electromagnetism, while eight different kinds of gluons play a similar role for the strong nuclear force.”
“However, there is one important difference: gluons themselves are subject to their own force, photons are not. This is why there are no bound states of photons, but a particle that consists only of bound gluons, of pure nuclear force, is in fact possible.”
Prof. Rebhan and his colleague, Frederic Brünner, have now employed a novel theoretical approach to calculate glueball decay.
They interpreted their results as strong evidence that a particle called meson f0(1710), which has been found in various experiments, is, in fact, the long-sought glueball.
Simplified model calculations have shown that there are two realistic candidates for glueballs: mesons f0(1500) and f0(1710).
“For a long time, meson f0(1500) was considered to be the most promising candidate. Meson f0(1710) has a higher mass, which agrees better with computer simulations, but when it decays, it produces many ‘strange’ quarks.”
“Our calculations show that it is possible for glueballs to decay predominantly into strange quarks,” Prof. Rebhan said.
“Surprisingly, the calculated decay pattern into two lighter particles agrees extremely well with the decay pattern measured for f0(1710).”
The results were published September 21 in the journal Physical Review Letters.
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Frederic Brünner & Anton Rebhan. 2015. Nonchiral Enhancement of Scalar Glueball Decay in the Witten-Sakai-Sugimoto Model. Phys. Rev. Lett., vol. 115, no. 13, 131601; doi: 10.1103/PhysRevLett.115.131601
