A new particle has been discovered at Fermilab’s Tevatron collider, and researchers say it’s exhibiting unusual properties.
Unlike normal particles, this one exotic particle contains four ‘flavours’ of quarks and antiquarks, making it a candidate for classification as a tetraquark.
Physicists say a particle like this would represent a new particle ‘species’, paralleling the ordinary subatomic particles known today.
An exotic particle contains additional quark-antiquark pairs to what’s seen in ordinary particles.
Mesons are composed of a quark and an antiquark, and baryons are made up of three quarks.
A tetraquark, however, is made up of four quarks, and a relative called the pentaquark is made up of five.
According to the data, the new X(5568) particle contains four distinct flavours of quarks and antiquarks – bottom, strange, up, and down.
The unusual particle was announced by the DZero collaboration at Fermilab as the result of the search for new exotic states decaying into a Bs meson and a pi meson.
These mesons travel finite distances, and then decay according to the weak nuclear interaction.
The study examined data obtained at the Tevatron collider over nearly ten years, from 2002 to 2011.
Researchers were able to identify the meson by its decay habits, transforming ‘into intermediate J/psi and phi mesons, which subsequently decayed into a pair of oppositely charged muons and a pair of oppositely charged K mesons respectively,’ according to Fermilab.
While normal Bs and pi mesons decay by the weak interaction, the data revealed a broad mass peak in the new state of this particle, indicating it decayed via the strong interaction.
This isn’t the first time physicists have detected exotic states, but previously observed candidates contained a quark and antiquark of the same flavour, making it less certain if they were actually exotic.
Unlike earlier candidates, this one has four distinct flavours.
The researchers say the internal structure of the new particle is not yet fully understood.
The quarks and antiquarks could be contained within a tightly bound unit, or they could be formed in revolving pairs of bound quark-antiquarks.
Understanding how these particles are composed and behave could provide researchers with new insight on the binding forces that hold quarks and antiquarks into observable particles.