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  2. Energy–momentum relation - Wikipedia

    en.wikipedia.org/wiki/Energymomentum_relation

    If the body is at rest (v = 0), i.e. in its center-of-momentum frame (p = 0), we have E = E 0 and m = m 0; thus the energymomentum relation and both forms of the mass–energy relation (mentioned above) all become the same. A more general form of relation holds for general relativity.

  3. Compton scattering - Wikipedia

    en.wikipedia.org/wiki/Compton_scattering

    The photon's momentum is then simply this effective mass times the photon's frame-invariant velocity c. For a photon, its momentum = /, and thus hf can be substituted for pc for all photon momentum terms which arise in course of the derivation below. The derivation which appears in Compton's paper is more terse, but follows the same logic in ...

  4. Feynman diagram - Wikipedia

    en.wikipedia.org/wiki/Feynman_diagram

    The Dyson series can be alternatively rewritten as a sum over Feynman diagrams, where at each vertex both the energy and momentum are conserved, but where the length of the energy-momentum four-vector is not necessarily equal to the mass, i.e. the intermediate particles are so-called off-shell. The Feynman diagrams are much easier to keep track ...

  5. Quantization of the electromagnetic field - Wikipedia

    en.wikipedia.org/wiki/Quantization_of_the...

    The photon having non-zero linear momentum, one could imagine that it has a non-vanishing rest mass m 0, which is its mass at zero speed. However, we will now show that this is not the case: m 0 = 0. Since the photon propagates with the speed of light, special relativity is called for. The relativistic expressions for energy and momentum ...

  6. On shell and off shell - Wikipedia

    en.wikipedia.org/wiki/On_shell_and_off_shell

    the mass–energy equivalence formula which gives the energy in terms of the momentum and the rest mass of a particle. The equation for the mass shell is also often written in terms of the four-momentum ; in Einstein notation with metric signature (+,−,−,−) and units where the speed of light c = 1 {\displaystyle c=1} , as p μ p μ ≡ p ...

  7. Photon - Wikipedia

    en.wikipedia.org/wiki/Photon

    The photon also carries spin angular momentum, which is related to photon polarization. (Beams of light also exhibit properties described as orbital angular momentum of light). The angular momentum of the photon has two possible values, either +ħ or −ħ. These two possible values correspond to the two possible pure states of circular ...

  8. Angle-resolved photoemission spectroscopy - Wikipedia

    en.wikipedia.org/wiki/Angle-resolved...

    It is based on the photoelectric effect, in which an incoming photon of sufficient energy ejects an electron from the surface of a material. By directly measuring the kinetic energy and emission angle distributions of the emitted photoelectrons, the technique can map the electronic band structure and Fermi surfaces .

  9. Two-photon physics - Wikipedia

    en.wikipedia.org/wiki/Two-photon_physics

    A Feynman diagram (box diagram) for photonphoton scattering: one photon scatters from the transient vacuum charge fluctuations of the other. Two-photon physics, also called gamma–gamma physics, is a branch of particle physics that describes the interactions between two photons. Normally, beams of light pass through each other unperturbed.