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Pair production often refers specifically to a photon creating an electron–positron pair near a nucleus. As energy must be conserved, for pair production to occur, the incoming energy of the photon must be above a threshold of at least the total rest mass energy of the two particles created. (As the electron is the lightest, hence, lowest ...
Pair production takes place exponentially slowly when the electric field strength is much below the Schwinger limit, corresponding to approximately 10 18 V/m. With current and planned laser facilities, this is an unfeasibly strong electric-field strength, so various mechanisms have been proposed to speed up the process and thereby reduce the ...
This expression can be derived by using a quantum mechanical symmetry between pair production and Bremsstrahlung. Z {\displaystyle Z} is the atomic number , α f i n e ≈ 1 / 137 {\displaystyle \alpha _{fine}\approx 1/137} the fine structure constant , ℏ {\displaystyle \hbar } the reduced Planck constant and c {\displaystyle c} the speed of ...
Pair production and annihilation: In the Stückelberg–Feynman interpretation, pair annihilation is the same process as pair production: Møller scattering: electron-electron scattering Bhabha scattering: electron-positron scattering Penguin diagram: a quark changes flavor via a W or Z loop Tadpole diagram: One loop diagram with one external leg
The creation of a much more massive pair, like a proton and antiproton, requires photons with energy of more than 1.88 GeV (hard gamma ray photons). The first published calculations of the rate of e + –e − pair production in photon-photon collisions were done by Lev Landau in 1934. [2]
Importantly, the energy of the colliding quark–antiquark pair can be almost entirely transformed into the mass of new particles. This process was first suggested by Sidney Drell and Tung-Mow Yan in 1970 [1] to describe the production of lepton–antilepton pairs in high-energy hadron collisions.
This fermion pair can be leptons or quarks. Thus, two-photon physics experiments can be used as ways to study the photon structure, or, somewhat metaphorically, what is "inside" the photon. The photon fluctuates into a fermion–antifermion pair. Creation of a fermion–antifermion pair through the direct two-photon interaction.
Since a ψ, ψ pair is a commuting element of the Grassmann algebra, it does not matter what order the pairs are in. If more than one ψ, ψ pair have the same k, the integral is zero, and it is easy to check that the sum over pairings gives zero in this case (there are always an even number of them). This is the Grassmann analog of the higher ...