Higgs-Boson Decay

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June 08, 2023

Why in news?

Physicists detected a Higgs boson decaying into a Z boson particle and a photon in the Large Hadron Collider (LHC) at CERN.

What is the Higgs boson?

  • The Higgs boson is the fundamental force-carrying particle of the Higgs field, which is responsible for granting other particles their mass.
  • Known as God’s Particle’, it was first discovered by the ATLAS and CMS detectors in 2012.
  • Properties - The Higgs boson has mass but is chargeless.
  • It has a mass of 125 billion electron volts.
  • It has zero spin, making it the only elementary particle with no spin.

How mass of other particles is related to Higgs Boson?

  • The mass of the subatomic particle depends on the particle’s interaction with the Higgs boson.
  • The stronger the interaction the more the mass it has.
  • Mass - Photons (particles of light) have no mass because they don’t interact with Higgs bosons.
  • The Higgs boson has a mass of 125 billion electron volts which is 130 times more massive than a proton.
  • A Higgs boson’s mass is greater than that of protons or neutrons because a Higgs boson can interact with another Higgs boson.

How universe could be studied using Higgs boson particles?

  • Universe - Higgs bosons can tell us a lot about the universe on studying two factors -
    • Understanding the properties of Higgs bosons
    • How strongly each type of atomic particle couples to Higgs bosons.
  • Virtual particles - According to quantum field theory, space at the subatomic level is filled with virtual particles.
  • They are particles that quickly pop in and out of existence which can’t be detected directly but their effects sometimes linger.

What is the Higgs Boson decay?

  • The LHC creates a Higgs boson by accelerating billions of highly energetic protons into a head-on collision.
  • This releases a tremendous amount of energy that condenses into different particles.
  • When a Higgs boson is created in LLHC, it has a brief interaction with virtual particles that creates a Z boson and a photon.
  • The Z boson is also unstable and decays to two muons some 3% of the time.

What is the Standard Model?

  • The Standard Model of particle physics explains how the basic building blocks of matter interact, governed by 4 fundamental forces.
  • The Standard Model is an established and well-tested theory of particle physics.
  • It successfully explained how these particles and 3 of the forces are related to each other.

Weak force, Strong force, Gravitational force and Electromagnetic force are the 4 Fundamental forces.

  • But it could not explain dark energy or the warping of space and time or hoe neutrinos have mass.
  • The Standard Model theory states that a Higgs boson will decay to a Z boson and a photon 0.1% of the time if its mass is 125 billion eV/c2.

How significant is the decay?

  • According to the Standard Model, 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.
  • The LHC would have had to create at least 30,000 Higgs bosons to observe the decay just once to spot a pair of muons plus a photon created at the same time.
  • Testing Standard models predictions as precisely as possible is a way to find whether there are any cracks in the Model.
  • Some theories predict a higher rate of decay through this pathway.
  • The experimental proof of this can validate new theories of physics and open new realm of science.

Quick Facts

Large Hadron Collider

  • The Large Hadron Collider (LHC) is the world’s largest and most powerful particle accelerator.
  • Started in 2008, it is located in the CERN’s accelerator complex.
  • It consists of a 27-kilometre ring in which two high-energy particle beams travelling in opposite directions are made to collide.
  • It has 4 particle detectors - ATLAS, CMS, ALICE and LHCb at 4 colliding locations around the accelerator ring.


  1. The Hindu - The decade-long search for a rare Higgs boson decay
  2. Science Alert - First Signs of Rare Higgs Boson Decay
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