From UPSC perspective, the following things are important :
Prelims level : LHCb experiments and its findings
Mains level : Formation of the universe and the Big Bang
The LHCb experiment at CERN (European Council for Nuclear Research) has announced the results of their latest analysis of data.
LHCb Experiment: An easy explanation
- LHCb is an experiment set up to explore what happened after the Big Bang that allowed the matter to survive and build the Universe we inhabit today.
- Fourteen billion years ago, the Universe began with a bang.
- Crammed within an infinitely small space, energy coalesced to form equal quantities of matter and antimatter.
- But as the Universe cooled and expanded, its composition changed.
- Just one second after the Big Bang, antimatter had all but disappeared, leaving the matter to form everything that we see around us — from the stars and galaxies to the Earth and all life that it supports.
What is the new finding?
- CERN scientists are excited enough to reveal that if the anomaly they had detected was confirmed.
- Because, if confirmed, it would require a new physical process, such as the existence of new fundamental particles or interactions.
What is this excitement all about?
It is necessary to delve into the world of elementary particles to understand this.
(1) Particle zoo
Until now it is believed that the electron, muon and tauon and their antiparticles, though they differ in mass, behave similarly in particle interactions.
- Broadly speaking, elementary particles are classified into the particles called baryons – which include protons, neutrons and their antiparticles the antiprotons etc.
- The “middle mass” particles, roughly speaking, are called the mesons and they include members such as the K and B particles.
- We then have the leptons, which include the electron and its cousins the muon and tau particles and the anti-particles.
- At a still smaller scale, there are tiny particles called quarks and gluons.
- There are six flavours of quarks: up, down, truth, beauty, charm and strange. They too have antiquarks associated with them.
In this particle zoo, while the baryons are made up of combinations of three quarks, the mesons contain two quarks, more accurately a quark and antiquark pair, and the leptons are truly fundamental and are thought to be indivisible.
Do you know?
Higgs Boson is called the god particle.
(2) Colliding particle beams
By interactions here, is meant the following:
- If a huge particle accelerator such as the LHC were to accelerate beams of hadrons (such as protons) to very high speeds, a fraction of that of light, and then cause them to collide.
- Basically, smash through the repulsive nuclear forces and shatter them, the hadrons would break up into constituents which would recombine to form short-lived particles, which would decay into stabler states.
- Roughly speaking, during this process, they are imaged in a huge multistorey detector and the number of specific processes and particles are counted.
(3) Lepton universality principle
- One such process that was measured was the decay of a meson B (which contained the beauty quark) into K-meson (which contains the strange quark) and a muon-antimuon pair, and this was compared with the decay of B into K and an electron-antielectron pair.
- The expectation is that the ratio of the strengths of these two sets of interactions would be just one.
- This is because the muons are not essentially different from the electrons as per the Standard Model, the presently accepted theoretical model of all elementary particle interactions.
- This is called the lepton universality principle.