Sun. Feb 1st, 2026

Researchers from Columbia University and Pennsylvania State University have discovered a particle called a semi-Dirac fermion.

Discovery process

  • Selected material: The researchers studied zirconium silicon sulfide (ZrSiS), a layered crystal material, and chose it as the host for the unusual particles.
  • Research findings: When a strong magnetic field was applied to ZrSiS, the energy of the electrons (cyclotron energy) increased on the B²/³ scale, a feature associated with semi-Dirac fermions. This was different from the energy scaling of materials such as graphene, where the energy increases on the B¹/² scale.
  • Quasiparticles: Semi-Dirac fermions are quasiparticles made up of many smaller particles and behave like particles, although they have abnormal mass in different directions.

1.Semi-Dirac Fermions: Semi-Dirac fermions are particles that have mass in one direction, while being massless in a perpendicular direction. This unique feature was discovered in a crystalline material called zirconium silicon sulfide (ZrSiS).

2.Dirac Fermions vs. Semi-Dirac Fermions:

Dirac Fermions

  • Have mass in all directions.
  • Are different from their anti-particles.

Semi-Dirac Fermions

  • Have mass in certain direction axes.
  • Behave differently under different conditions due to interactions with electric and magnetic forces in particular materials.

3. Quasi-particles

  • Semi-Dirac fermions are quasi-particles that:Behave like a single particle under specific conditions.They are made up of many energy packets or particles (such as protons).

Standard Model of Particle Physics

  • The Standard Model (SM) is a theoretical framework in particle physics that describes three of the four known fundamental forces in the universe – electromagnetic, weak, and strong interactions – and classifies all known elementary particles.
  • Developed in the early 1970s, it has been instrumental in explaining a wide range of experimental results and predicting new phenomena.

Fermions and Bosons

Fermions

  • Fermions (quarks + leptons) are fundamental particles with half-integer spin.
  • Fermions are the fundamental building blocks of matter.

Examples

  • Electron (leptons)
  • Proton (quarks)

Bosons

  • Bosons are the particles that transmit the fundamental forces.
  • Each fundamental force has its own corresponding force transmitter (boson).

Examples

  • Photon: Transmitter of electromagnetic force
  • Glyon: Transmitter of strong force
  • W and Z bosons: Transmitter of weak force

Gravitational force

  • This is a suggested force transmitter that would transmit the gravitational force, but it has not been discovered yet.

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