Friday, July 17, 2020

Discovery of a new particle: A Charming Tetraquark

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Hardi Talwani

Article Title

Discovery of a new particle: A Charming Tetraquark

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Global Views 360

Publication Date

July 17, 2020

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The Large Hadron Collider

The Large Hadron Collider | Source: Anna Pantelia via CERN

While the world is horrified by the novel Coronavirus, scientists at the European Centre for Nuclear Research (CERN) announced the discovery of a never seen before tetraquark. Any finding in particle physics is a phenomenal one because it could tell us a lot about the origins of the universe and how everything came to be. And this discovery is quite charming and quarky (quirky).

Quarks are the elementary particles so any further division of these particles is not possible. This means everything in the universe is ultimately a combination of Quarks. Any new discovery of Quarks  therefore increase our understanding about the origin of universe

When three Quarks come together, they form familiar particles known as Baryons, for instance, protons and neutrons, found in the nucleus of an atom. A tetraquark, in particle physics, is an exotic meson composed of four quarks.

Murray Gell-Mann, recipient of the 1969 Nobel Prize in Physics for his work on the theory of Elementary particles, chose the name ‘Quark’. Another scientist,  George Zweig from CERN also proposed the Quark theory independently of Gell-Mann.

All the new particles are detected using particle accelerators where particles are accelerated at almost the speed of light and collide to look into their subsets. It is like knocking two rocks together so that they break into smaller constituents.

The most recent tetraquark, named X (6900) was discovered by CERN physicists while working on LHCb (Large Hadron Collider beauty experiment). The already known tetraquarks contain a particular combination of two relatively heavy quarks and two light Quarks. On the other hand X(6900) consists of four heavy Quarks: two Quarks and two anti-Quarks.

This exclusive particle made of unusual combinations is a perfect setting for understanding the fundamental force of nature known as Strong Interaction. The strong force is vital to comprehend as it binds together protons, neutrons and the nucleus that ultimately make up matter. Another perk of X(6900)  is its relatively heavy mass, so these are simpler to look at and are more stable as compared to notoriously fast moving-lighter ones.

The paper written by 800 scientists is yet to be peer-reviewed. The bump observed has a statistical significance of more than five sigma (standard deviations) that is good enough to claim the discovery of a new particle.

In any scenario, this unusual discovery will serve as a piece for completing the puzzle of our universe while serving as evidence of the presence of new particles not yet found.

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February 4, 2021 4:44 PM

World's largest graveyard of Dinosaurs found in South Africa

In a village in the eastern cape of South Africa lies one of the most significant dinosaur sites ever found in the world. The site was discovered when a shepherd, Dumangwe Thyobeka found a large bone on his way to his great-grandparents’ graves, in 2015. He then took the bones to a local dinosaur enthusiast, James Rhalene. Commenting on this discovery " Mr. Rhalene said, "Growing up we were told dinosaurs were a myth, I thought they were only tales our grandparents would tell around the fire at story time", and It wasn't until reading some books that I started to believe they may be real. I've been looking into the existence of dinosaurs since 1982. He added, "You can imagine my excitement at being part of this and discovering them in my own backyard. I am so proud. Books will be written about our small village; the world will come to know of us through this discovery.”

These bones are more than 200 million years old, of around the end of the Triassic era and the beginning of the Jurassic one. When the village elder, Sginyane Ralane came to know about the discovery, he reached out to universities in South Africa for looking into it. The news eventually reached Prof. Jonah Choiniere from the University of Witwatersrand in Johannesburg, and in 2018 Jonah and his colleagues started excavating the site. “It has been one of those places where you sometimes find yourself literally tripping over a dinosaur bone. There are very few other sites I've had the chance to work where we have this richness of fossils.” says Prof Paul Barett, a dinosaur expert at The Natural History Museum, UK, after he joined the team.

A reason why this area is abundant in fossils, Natural History Museum explains, is because of the ancient river systems in the area. The area is arid for most of the year now, and the rivers flow only seasonally. However, in the ancient times, there were vast river systems flowing year-round in the region, with wide, shallow rivers which would consequently form a layer of rock 210 million years old which is up to 500 meters thick in some regions. These rivers supported diverse wildlife, including ancestors of crocodiles, possibly those of turtles and mammals and fish, amphibians and reptile-like animals. The existence of such large rivers meant that dead animals nearby would be buried in sediment before they decomposed.  

This discovery is scientifically important for a number of reasons; the era from which these bones are found is a boundary in which a mass extinction occurred. Prof. Jonah is trying to understand how the animals from before that extinction survived and how they flourished after. In the Triassic era, there were multiple dominating animals, like the crocodiles, big mammal-like animals and dinosaurs. In the Jurassic era, however, the dinosaurs are clearly dominating. Why this happened is unclear, and the rocks and fossils from this site might help with that. There were also other animals along with dinosaurs in this site which make it noteworthy. Of the animals found, there were rauisuchians, which relate to modern-day crocodiles, and were dominant on land during the Triassic. The team also found cyclodonts and dicyclodonts, where the cyclodonts are the early ancestors to all mammals, and dicyclodonts are an even earlier branch of the mammalian family tree.

All of these have a significant impact on the community too; the team signed a memorandum of understanding with the local government with huge. After the signing, local officials visited the site at Qhemega. The team has been trying to use the heavy machinery they had brought for moving fossils for improving access in and to the village. They are also developing a curriculum in high schools to include topics about fossil sites and to add geography to the curriculum, to train the younger generation about the mapping used in excavation and in many other scientific fields especially relevant in the mineral-resource rich South Africa.

So far, this site has only provided benefits for everyone involved; new discoveries and confirming data for the scientific community, and economic access, increased opportunities and a matter for pride for the local community.

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