Pair production physics Watch

amy_elizabeth64
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Why can't a photon produce a SINGLE electron rather than an electron and a positron? help please!
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alex3107_
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Conservation laws. Charge and lepton number must be conserved. Beforehand the photon has a charge and lepton number of 0. Afterwards, an electron has a charge of -1 and a lepton number of +1, hence a positron also needs to be created (as it has a charge of +1 and a lepton number of -1) so that they cancel out out and give a charge and lepton number of 0. The same as the photon.
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Doctor_Einstein
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(Original post by amy_elizabeth64)
Why can't a photon produce a SINGLE electron rather than an electron and a positron? help please!
Because something of neutral charge (a photon) cannot spontaneously form something of negative charge (an electron), without balancing it with a positive charted particle (a positron).
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