Matter and Anti-Matter

Matter and Anti-Matter Latest News

Recently, physicists at CERN’s Large Hadron Collider beauty (LHCb) experiment reported confirmed evidence of Charge-Parity (CP) violation in a class of particles called baryons.

Matter

• Matter is anything that has mass and occupies space, composed of atoms and molecules.
• Primary States:
  • Solid: Fixed shape and volume.
  • Liquid: Fixed volume, no fixed shape.
  • Gas: No fixed shape or volume.
• Fourth State – Plasma:
  • Consists of ionized particles.
  • Found in stars and high-energy environments.
• State Changes: Driven by temperature and pressure, e.g., melting, evaporation, condensation.

Antimatter

• Antimatter consists of particles that are mirror counterparts of matter, with opposite electric charge.
  • Electron → Positron, Proton → Antiproton, Neutron → Antineutron
• Creation: Both matter and antimatter were created during the Big Bang in equal amounts.
• Interaction: When matter and antimatter collide, they annihilate each other, producing gamma rays.
• Sources:
  • Natural: Cosmic rays and radioactive decay.
  • Artificial: Particle accelerators like the LHC simulate conditions similar to the Big Bang, producing antiparticles.

Key Concepts and Definitions

• CP Violation (Charge-Parity Violation): CP violation refers to a discrepancy in the behavior of matter and antimatter counterparts under a combination of charge conjugation (C) and parity transformation (P).
  • Charge conjugation (C) changes a particle into its antiparticle, while parity (P) flips the spatial coordinates (like a mirror reflection).
  • Ideally, CP symmetry implies that matter and antimatter should behave identically in physical processes. Violation of this principle hints at an inherent asymmetry.
• Baryons and Antibaryons: Baryons are subatomic particles made of three quarks. The most common examples are protons and neutrons.
  • Their antimatter counterparts, called antibaryons, are composed of three antiquarks.

Latest Discovery: What Did the LHCb Find?

• Physicists studied a baryon called the lambda-b (Λb) particle, composed of up (u), down (d), and bottom (b) quarks.
• The lambda-b baryon was observed decaying into a proton, a kaon, and two pions.
• A small but statistically significant difference was found in the decay rate between the lambda-b baryon and its antimatter counterpart, indicating CP violation.
• This is the first discovery of CP violation in baryons to surpass the five-sigma statistical threshold, a standard benchmark for declaring a scientific discovery.

Matter and Anti-Matter FAQs

Q1. What is antimatter?
Ans. Particles with identical mass but opposite charge to matter (e.g., positrons vs. electrons). Their collision releases energy (E=mc²).

Q2. Why is the matter-antimatter asymmetry significant?
Ans. The universe’s dominance of matter (baryon asymmetry) remains unexplained, challenging the Standard Model of particle physics.

Q3. How is antimatter used practically?
Ans. PET scans use positrons for cancer detection. CERN produces nanograms annually for research, costing ₹500 crore/gram.

Source: SCN