Three New ‘Exotic’ Sub-Atomic Particles

Context:

The Large Hadron Collider beauty (LHCb) experiment, which is looking at the distinctions between matter and antimatter by researching a type of particle known as the “beauty quark,” or “b quark,” has discovered three previously unseen particles.

Relevance:

GS Paper3: Science and Technology (Recent developments and their applications and effects in everyday life, Achievements of Indians in science & technology.)

Mains Questions:

• Give a brief account of Quarks and Leptons and also comment on new discoveries in Particle physics around the world.  

Dimension of the article:

• The extent of Particle Physics
• Quarks, Leptons, Fermions, Bosons

Three New Exotic Aditions:

The three “exotic” additions to the increasing list of new hadrons discovered at the LHC — a new type of “pentaquark” and the first-ever pair of “tetraquarks” — will help physicists better grasp how quarks bond together to form these composite particles, CERN said in a release.

What are quarks?

• Quarks and leptons are the two main types of elementary particles. There are six types of Quarks and six types of Leptons, that can be classified into six “flavours”: up, down, charm, weird, top, and bottom.
• Quarks and Leptons are members of a broader class known as Fermions. Fermions have spins such as 1/2, 3/2, 5/2, and so on. Quarks and Leptons are Fermions with 1/2 spin.
• The six quarks are paired in three generations, beginning with the “up quark” and “down quark,” followed by the “charm quark” and “strange quark,” then the “top quark” and “bottom (or beauty) quark.” The first generation consists of the lightest and most stable particles, whereas the second and third generations consist of heavier and less stable particles.
• All stable matter in the universe is composed of particles from the first generation; heavier particles swiftly decay to the next most stable level.
• Quarks frequently combine in groups of twos and threes to form hadrons, which are composed of protons and neutrons to form atomic nuclei.
• They can, however, combine to generate tetraquarks and pentaquarks, which are four- and five-quark particles.
• These exotic hadrons were predicted by theorists around six decades ago — around the same time as conventional hadrons were found — but they were only recently discovered by LHCb and other experiments.

Bosons:

• All bosons have a zero or an integer spin.
• Bosons can be in the same quantum state as other bosons, as in laser light, which is made up of coherent, overlapping photons.
• Indeed, the more bosons in a state, the more likely it is that another boson will join that state (Bose condensation).
• Fermions are typically connected with matter, whereas Bosons are related with force.
• Fundamental particles such as photons, gluons, W and Z bosons (the four force-carrying gauge bosons of the Standard Model), and the Higgs boson are examples of bosons.

Tetraquarks and Pentaquarks

• The most exotic hadrons discovered in the last two decades, according to CERN, are tetraquarks or pentaquarks having a charm quark and a charm antiquark, with the remaining two or three quarks being an up, down, or strange quark or their antiquarks.
• However, the LHCb experiment discovered an unusual tetraquark composed of two charm quarks and two charm antiquarks, as well as two “open-charm” tetraquarks composed of a charm antiquark, an up quark, a down quark, and a weird antiquark two years ago.
• CERN also announced last year that it discovered the first-ever instance of a “double open-charm” tetraquark with two charm quarks and an up and a down antiquark.
• The particle is said to be open charm if it contains a charm quark but no antiquark.

Exotic Hadrons

• The first type was discovered while studying “decays” of negatively charged B mesons.
• According to CERN, it is a pentaquark composed of a charm quark and a charm antiquark, as well as an up, a down, and a strange quark.
• It is the first pentaquark discovered to include an unusual quark.
• According to the statement, the discovery has a statistical significance of 15 standard deviations, significantly exceeding the 5 standard deviations required to claim the observation of a particle in particle physics.
• A doubly electrically charged tetraquark is the second type. It’s an open-charm tetraquark made up of a charm quark, an odd antiquark, an up quark, and a down antiquark.
• According to the CERN statement, it was discovered alongside its neutral counterpart in a joint examination of decays of positively charged and neutral B mesons.