HIGGS BOSON

1. Context

Recently, physicists working with the Large Hadron Collider (LHC) particles masher at CERN, in Europe, reported that they had detected a Higgs boson decaying into a Z boson particle and a photon. This is a very rare decay process that tells us important things about the Higgs boson as well as about our universe.

2. What is Higgs Boson?

The Higgs boson is one of the 17 fundamental particles that constitute the Standard Mode of particle physics, and the best scientific hypothesis on the behavior of the building blocks of the Universe.
It is often called the "God Particle" because it is significant in subatomic physics.
The Higgs boson is the elementary particle related to the Higgs field that imparts mass to other elementary particles like Quarks and electrons.
When a particle is subjected to a force, its mass decides how much it affects its speed or position.
All elementary particles do not have mass, such as Photon, which carries electromagnetic energy but lacks mass.
A particle's mass is the amount of inertia that defines its presence at any given location.

3. What is a Higgs Field?

As proposed by Peter Higgs in 1964, the Higgs field is the field of energy that permeates the universe.
The Higgs field is an invisible field where elementary particles gain mass after interacting with it. Diverse Particles, like electrons, quarks, photons, etc., have varying masses because the Higgs field does not affect them equally.
The greater a particle's binding strength to the Higgs field, the bigger it's mass.
Physicists had a solid theory about electromagnetic and weak nuclear interactions in the early 1960s.
However, deep similarities were discovered between the two. Still, a theoretical approach at a higher level demanded that particles be massless, given the reality that particles in nature had mass.
In 1964, Peter Higgs presented his original manuscript about the Higgs field (then unnamed) to the journal Physical Review Letters.
He revised his paper and added a new prediction that a new elementary particle should be linked to the Higgs field.
It belonged to a new class of elementary particles known as bosons, possessing high mass. This particle was later named the Higgs boson.

4. Discovery of Higgs Boson

Higgs’ hypothesis proved to be appealing for the masses of all elementary particles. The only way to confirm the theory was to examine a Higgs boson.
The Higgs boson was anticipated to be unstable, breaking into numerous particles in a microsecond.
By subatomic standards, its enormous mass meant that only extremely high-energy collisions could produce it.
Observing the Higgs boson was one of CERN’s primary goals when it built the Large Hadron Collider (LHC), the world’s most powerful particle accelerator.
When the LHC started in 2008, scientists only knew of the Higgs Boson because its mass had to be larger than 114 billion electron volts (eV).
The LHC stood up to the challenge, with a growing number of observations showing a Higgs-like particle of about 125 billion eV. CERN announced the discovery of the Higgs boson on July 4, 2012, 50 years after its initial proposal.
Francois Englert and Peter Higgs won the 2013 Nobel Prize in Physics for their theoretical discovery of the Higgs mechanism, which contributed significantly to the origin of the mass of subatomic particles and confirmed the discovery of the Higgs boson fundamental particle.
The discovery was historic because it established the existence of the Higgs field, required for the Standard Model and many other particle physics theories.

5. Results of the study

According to quantum field theory, which is the theory physicists use to study these interactions, space at the subatomic level is not empty.
It is filled with virtual particles, which are particles that quickly pop in and out of existence. They can’t be detected directly, but according to physicists their effects sometimes linger.
The LHC creates a Higgs boson by accelerating billions of highly energetic protons into a headon collision, releasing a tremendous amount of energy that condenses into different particles.
As it is a heavy particle, the Higgs boson is unstable and decays into lighter particles.
We can’t always say which combination of particles it will decay into.
But, the theory that describes the properties of fundamental particles has predicted the probability that it will take a given path.
For example, this theory called the Standard Model, says that a Higgs boson will decay to a Z boson and a photon 0.1% of the time.
This means the LHC needed to have created at least 1,000 Higgs bosons to have been able to spot one of them decaying to a Z boson and a photon.
As it happens, the Z boson is also unstable. According to Martin Bauer, an associate professor at the Institute for Particle Physics Phenomenology, Durham University, Z bosons decay to two muons some 3% of the time.

6. Implications

The two detectors that announced the new measurement, called ATLAS and CMS had looked for and found the decay before as well (in 2018 and 2020).
On this occasion, the two teams combined their data, collected “between 2015 and 2018”, and as a result “significantly increased the statistical precision and reach of their searches,” according to a CERN statement.
This significance is even now not high enough for the teams to claim that a Higgs boson decays to a Z boson and a photon with 100% certainty, reflecting the rarity of the decay pathway.
The Standard Model has made many. The Standard Model has made many accurate predictions but it can’t explain what dark matter is or why the Higgs boson is so heavy.
Testing its predictions as precisely as possible is a way for physicists to find whether there are any cracks in the Model cracks through which they can validate new theories of physics.
For example, some theories predict a higher rate of decay through this pathway; if the LHC and its detectors find experimental proof of that, the new theories could open a new realm of science.

7. Large Hadron Collider (LHC)

LHC was constructed to determine what is the Higgs field, how it operates, and whether it is elementary or composite.
The LHC was designed to accomplish much more than identify the Higgs Boson. In Switzerland and France, scientists built the world’s most powerful and largest particle accelerator in an underground tunnel of 100m.
They propelled protons around the LHC’s 17-mile ring of superconducting magnets with an energy of up to 7 TeV.
Scientists examined the speeding particles after slamming them together for signs of a degraded Higgs.
The discovery of the Higgs boson was announced after two years of operation and over 300 trillion unique collisions.

For Prelims: Large Hadron Collider, Higgs Boson, Higgs field, electron volts (eV), Z boson, Quarks, and electrons.

Previous year Question

1. The efforts to detect the existence of Higgs boson particles have become frequent news in the recent past. What is/are the importance/importance of discovering this particle? (UPSC 2013)

1. It will enable us to understand as to why elementary particles have mass.

2. It will enable us in the near future to develop the technology of transferring matter from one point to another without traversing the physical space between them.

3. It will enable us to create better fuels for nuclear fission.

Select the correct answer using the codes given below.

A. 1 only

B. 2 and 3 only

C. 1 and 3 only

D. 1, 2 and 3

Answer: A

2. Recently scientists observed the merger of giant 'black holes' billions of light years away from the Earth. What is the significance of this observation? (UPSC 2019)

A. 'Higgs boson particles' were detected

B. 'Gravitational waves' were detected.

C. Possibility of inter-galactic space travel through a 'wormhole' was confirmed.

D. It enabled the scientists to understand 'singularity'.

Answer: B

Source: The Hindu

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