A team of particle scientists from Austria claim to have finally located a glueball which is a particle made of nuclear force and theorised to exist as per the standard model of particle physics. The paper is published in Physical Review Letters.
A glueball (right) made of gluons (force particles). Gluons & quarks (matter particles) making up nucleons (left).
Glueballs have hitherto not been detected, mostly because they can only be found indirectly by calculating their process of decay – thus was what the scientists from Austria observed. They recorded the decay of a particle known as f0(1710), a potential candidate for being a glueball.
What are glueballs?
Glueballs result from the adherence of gluons – which are tiny particles causing quarks to stick together – to each other through their own nuclear force.
Gluons which are commonly known as ‘sticky particles’ are said to exert a strong nuclear force; in this manner, they are often compared to photons which provide the force of electromagnetism.
“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,” explains one of the researchers, Anton Rebhan from the Vienna University of Technology.
Unlike photons, gluons are affected by the force they exert such that they are able to bind together into glueballs.
Glueballs also have mass. While gluons are massless as entities on their own, their interactions cause the aggregation to have mass. This is exactly what enables scientists – theoretically, at least – to detect them through their decay process.
The f0(1710) is a subatomic particle also known as meson consisting of one quark and one antiquark. Scientists initially had difficulties in proving whether it was a glueball or not because its decay would produce ‘strange quarks’. The new data now point at otherwise.
“Our calculations show that it is indeed possible for glueballs to decay predominantly into strange quarks,” explains Rebhan.
The physicists now hope that new findings from experiments at the Large Hadron Collider at CERN (TOTEM and LHCb) in Switzerland and an accelerator experiment in Beijing (BESIII) will help corroborate their own data.
“These results will be crucial for our theory,” says Rebhan. “For these multi-particle processes, our theory predicts decay rates which are quite different from the predictions of other, simpler models. If the measurements agree with our calculations, this will be a remarkable success for our approach.”