by EVRIM YAZGIN
A Large Hadron Collider experiment at CERN’s particle accelerator in Switzerland has led to the first observation of a doubly charged tetraquark and its neutral partner.
Measurements of elusive and exotic particles may open up new avenues of research and help scientists develop fundamental theories such as the Standard Model of particle physics which aims to explain the relationships between the elementary particles and forces of nature.
Included in the Standard Model are particles known as quarks.
Quark model
The quark model was introduced in 1964. Its theory predicts the existence of elementary particles that can be found in different configurations to form other particles.
For example, neutrons and protons – the subatomic particles that make up the atomic nucleus – are actually composite particles made up of 3 quarks bound together by the strong nuclear force. Protons are made up of 2 up quarks and 1 down quark. Neutrons are composed of 1 up quark and 2 down quarks.
But the theory around quarks and anti-quarks (the anti-matter equivalent of quarks) also predicts more complex particles made up of four or five quarks – tetraquarks and pentaquarks, respectively.
Scientists have been looking for these composite particles for more than a decade in an experiment called LHCb – Large Hadron Collider beauty. Now, researchers involved in the experiment have reported in Physical Review Letters the first observation of a doubly charged tetraquark and its neutrally charged anti-matter partner.
“In the past decade, the LHCb experiment has done pioneering work in the discovery of so-called exotic particles,” team member Dr Yasmine Sara Amhis, physics coordinator of the LHCb experiment, says in an article on Phys.org. “The LHCb discovered the first pentaquark in 2015, and this opened the road to many other findings. The primary objective of LHCb’s research into exotic particles is to discover which tetraquarks and pentaquarks exist and to map their properties, especially uncovering the other particles they decay into and their quantum numbers.”
Investigations could help determine which of the different models used to describe tetraquarks and pentaquarks are correct and any discrepancies or inaccuracies between them.
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