page_title: Electron–positron annihilation
hierarchical_section_title: Electron–positron annihilation
caption_attribution_description: English: Image of the "annihilation" process known in elementary physics. It shows how a positron (e+) is emitted from the atomic nucleus together with a neutrino (v). The positron moves then randomly through the surrounding matter where it hits several different electrons (e-) until it finally loses enough energy that it interacts with a single electron. This process is called an "annihilation" and results in two diametrically emitted photons with a typical energy of 511 keV each. However, please note that under normal circumstances the photons are not emitted exactly diametrically (180 degrees). This is due to the remaining energy of the positron and therefore of the conservation of momentum. Español: Esquema de una aniquilación electrón-positrón
context_page_description: Electron–positron annihilation occurs when an electron and a positron collide. At low energies, the result of the collision is the annihilation of the electron and positron, and the creation of energetic photons:
  e⁻
  +
  e⁺
  →
  γ
  +
  γ
  At high energies, other particles, such as B mesons or the W and Z bosons, can be created. All processes must satisfy a number of conservation laws, including:
  Conservation of electric charge. The net charge before and after is zero.
  Conservation of linear momentum and total energy. This forbids the creation of a single photon. However, in quantum field theory this process is allowed; see examples of annihilation.
  Conservation of angular momentum.
  Conservation of total lepton number, which is the number of leptons minus the number of antileptons; this can be described as a conservation of matter law.
  As with any two charged objects, electrons and positrons may also interact with each other without annihilating, in general by elastic scattering.
context_section_description: Electron–positron annihilation occurs when an electron (
  e⁻
  ) and a positron (
  e⁺
  , the electron's antiparticle) collide. At low energies, the result of the collision is the annihilation of the electron and positron, and the creation of energetic photons:
  e⁻
   + 
  e⁺
   → 
  γ
   + 
  γ
  At high energies, other particles, such as B mesons or the W and Z bosons, can be created. All processes must satisfy a number of conservation laws, including:
  Conservation of electric charge. The net charge before and after is zero.
  Conservation of linear momentum and total energy. This forbids the creation of a single photon. However, in quantum field theory this process is allowed; see examples of annihilation.
  Conservation of angular momentum.
  Conservation of total (i.e. net) lepton number, which is the number of leptons (such as the electron) minus the number of antileptons (such as the positron); this can be described as a conservation of (net) matter law.
  As with any two charged objects, electrons and positrons may also interact with each other without annihilating, in general by elastic scattering.
caption: Naturally occurring electron-positron annihilation as a result of beta plus decay
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