Physicists Say They Have Found An Exotic Particle called Tetraquark
The LHCb collaboration at CERN has announced the invention of a replacement Exotic Particle: a so-called “Tetraquark”. The paper by quite 800 authors is yet to be evaluated by other scientists during a process called “peer review” but has been presented at a seminar. It also meets the standard statistical threshold for claiming the invention of a replacement particle.
The finding marks a serious breakthrough during a search of just about 20 years, administered in high energy physics labs everywhere the planet. To understand what a Tetraquark is and why the invention is vital. We did like to step back in time to 1964, when high-energy physics was within the middle of a revolution. Beatlemania had just exploded, the Vietnam War was raging and two young radio astronomers in New Jersey had just discovered the strongest evidence ever for the Big Bang theory.
On the opposite side of the US, at The California Institute of Technology, and The Atlantic, at CERN in Switzerland. Two particle physicists were publishing two independent papers on an equivalent subject. Both were about the way to add up of the big number of latest particles that had been discovered over the past 20 years.
Many physicists struggled to simply accept that numerous elementary particles could exist within the universe, in what had become referred to as the particle zoo. Caltech’s George Zweig and Gell Mann from CERN had struck upon an equivalent solution. What if of these different particles were really made from smaller, unknown building blocks, with in the same way that the hundred odd elements with in the table are made from protons, neutrons and electrons? Zweig called these building blocks “aces”, while Gell Mann chose the term that we still use today: “Quarks”.
We now know that there are six different sorts of quarks– up, down, charm, strange, top, bottom. These particles even have respective antimatter companions with opposite charge, which may bind together consistent with simple rules supported symmetries.
A particle made from a Quark and an Antiquark is named a Meson. While three quarks bound together form baryons (subatomic particle having mass greater or equal to that of proton). The familiar protons and neutrons that structure the atomic nucleus are samples of baryons.
This classification scheme beautifully described the particle zoo of the 1960s. However even in his original paper Gell Mann realized that other combinations of quarks could be possible. For instance, two quarks and two antiquarks might stay together to make a tetraquark. While four quarks and an antiquark would make a “Pentaquark“.
Fast forward to 2003, when the Belle Experiment at the KEK laboratory in Japan reported the observation of a replacement Meson called X(3872), which showed “Exotic” properties quite different from ordinary mesons.
In the following years, several new exotic particles were discovered and physicists began to realize that the majority of those particles could only be explained successfully, if they were tetraquarks made from four quarks rather than two. Then, in 2015, the LHCb experiment at CERN discovered the primary Pentaquark Particles made from five quarks.
All Tetraquarks and Pentaquarks that are discovered thus far contain two Charm Quarks. Which are relatively heavy, and two or three light quarks – up, down or strange. This particular configuration is indeed the simplest to get in experiments.
But the newest tetraquark discovered by LHCb, which has been dubbed X(6900), consists of Four Charm Quarks. Produced in high energy proton collisions at the massive Hadron Collider. The new tetraquark was observed via its decay into pairs of well known particles called J/psi mesons, each made from a quark and a Charm Antiquark. This makes it particularly interesting because it is not only composed entirely of heavy quarks, but also four quarks of an equivalent kind-making it a singular specimen to check our understanding on how quarks bind together.
Huge round chamber filled with tall, multicolored trusses and machinery with one tiny man standing on the ground .
For now, there are two different models that would explain how quarks bind together. It might be that they are strongly bound, creating what we ask as a compact tetraquark. Or might be that the quarks are arranged to make two mesons (subatomic particle whose mass lie between electron and proton) which are stuck together loosely during a “Molecule”.
Ordinary molecules are made up of atoms bound together by the electromagnetic force, which acts between charged nuclei and charged electrons. But the quarks during a meson or baryon are connected via a special force, the “Strong Force”. It’s really fascinating that atoms and quarks, following very different rules, can both form very similar complex objects.
The exotic particle appears to be most according to being a compact tetraquark instead of a two meson molecule. Which was the simplest explanation for previous discoveries. This makes it unusual, because it will allow physicists to review this new binding mechanism intimately. It also implies the existence of other heavy compact tetraquarks.
Window Into Micro-Cosmos
The strong interaction operating between quarks obeys very complicated rules. So complicated, in fact, that sometimes the sole thanks to calculate its effects is to use approximations and supercomputers.
The unique nature of the X(6900) will help understand the way to improve the accuracy of those approximations, in order that with in the future we will be ready to describe other, more complex mechanisms in physics that are not with in our reach today.
Since the invention of the X(3872), the study of exotic particles has going well, with many theoretical and experimental physicists working together to shed some light on this exciting new field. The invention of the new Tetraquark may be a huge breakthrough, and is a sign that there are still many new Exotic Particles out there, expecting someone to unveil them.