Standard Model of Particle Physics and Electric Dipole Moment

• 29 Jul 2023

Source: TH

Why in News?

Some physicists are doing experiments to find flaws in a theory called the Standard Model of particle physics with taking electron dipole moment into consideration.

What is the Standard Model of Particle Physics?

• About:
  • The Standard Model of particle physics is a theoretical framework that describes the fundamental particles and their interactions.
  • It incorporates three of the four fundamental forces of nature: electromagnetism, the weak nuclear force, and the strong nuclear force, while gravity is not included in this model.
• Components:
  • Elementary Particles: The model classifies particles into two main categories: fermions and bosons.
  • Fermions: These are particles that make up matter. They are further divided into two groups:
    • Quarks: The building blocks of protons and neutrons, among other particles.
    • Leptons: Include particles like electrons.
  • Bosons: These particles are responsible for mediating the fundamental forces between fermions. It includes Photons, W and Z bosons, Gluons, Higgs boson.
• Limitations:
  • It does not account for dark matter and dark energy, which are significant components of the universe.
    • It doesn’t know why the Higgs boson is so heavy or why gravity is so much weaker than the other fundamental forces.
  • It also does not provide a quantum theory of gravity, which is needed to understand phenomena such as black holes and the Big Bang.

How does the Electron Play an Important Role in Testing the Standard Model?

• The electron is one of the simplest and most precisely measured particles in nature. It has a negative electric charge, a spin (a form of intrinsic angular momentum) and a mass, but no other known properties.
  • According to the Standard Model, the electron should have a spherical shape, meaning that its positive and negative charges are distributed evenly around its center.
• This implies that it has no electric dipole moment (EDM), which is a measure of how its charges are separated along its spin axis.
• Therefore, measuring the EDM of the electron is a sensitive way to test the validity of the Standard Model and to probe for new physics beyond it.

What is Electric Dipole Moment?

• An EDM is a concept in physics that describes the separation of positive and negative charges within an object, creating a dipole. It is a vector quantity that measures the strength and direction of this charge separation.
  • The strength of the dipole depends on how big the charges are and how far apart they are from each other.
• Electric dipoles are relevant in understanding the behavior of molecules, atoms, and even tiny particles that make up matter.
  • Scientists study electric dipole moments to explore important questions, like why there is more matter than antimatter in the universe, and to search for new physics beyond our current understanding.

UPSC Civil Services Examination, Previous Year Questions (PYQ)

Q1. The terms ‘Event Horizon’, ‘Singularity’, ‘String Theory’ and ‘Standard Model’ are sometimes seen in the news in the context of (2017)

(a) Observation and understanding of the Universe
(b) Study of the solar and the lunar eclipses
(c) Placing satellites in the orbit of the Earth
(d) Origin and evolution of living organisms on the Earth

Ans: (a)