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.

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

WHAT IS A QUARK? Quarks are elementary particles, the smallest particles we know to exist. When they combine they form compound particles known as hadrons. Quarks are said to have six ‘flavours’: Up, Down, Charm, Strange, Top and Bottom. Combinations of quarks within these flavours gives rise to the ‘larger’ particles. Groups of three quarks are known as baryons. An example of a baryon is a proton, which is made of two 'Up' quarks and a 'Down' quark. Advertisement Advertisement

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.

SUBATOMIC PHYSICS IN BRIEF Atoms are usually made of protons, neutrons and electrons These are made of even smaller elementary particles. Elementary particles, also known as fundamental particles, are the smallest particles we know to exist. They are subdivided into two groups, the first being fermions, which are said to be the particles that make up matter. The second are bosons, the force particles that hold the others together. Within the group of fermions are subatomic particles known as quarks. When quarks combine in threes, they form compound particles known as baryons. Protons are probably the best-known baryons. Sometimes, quarks interact with corresponding anti-particles (such as anti-quarks), which have the same mass but opposite charges. When this happens, they form mesons. Mesons often turn up in the decay of heavy man-made particles, such as those in particle accelerators, nuclear reactors and cosmic rays. Mesons, baryons, and other kinds of particles that take part in interactions like these are called hadrons. Advertisement

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

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.



