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Creation of a fundamental particle

  1. Jan 19, 2013 #1
    Do I always have to use pair production for the fundamental particles... If I have to produce a fermion,I have to create an anti fermion at the same time? what about bosons? i mean what about those who doesn't have antiparticle? Or do I have to create 2 of them as they themselves are their own anti particle?
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  3. Jan 19, 2013 #2


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    I'm a bit puzzled here.

    An electron is a "fundamental particle". I can create it easily via either the photoelectric effect, or thermionic emission. I have created no positron in that process, i.e. I didn't use any pair production.

  4. Jan 19, 2013 #3
    The photoelectric effect does not create electrons - they are already present in the metal; the photon absorption just provides enough energy to free them.

    Yes, to create a fermion from a bosonic state, you always have to create an anti-fermion. But it is not necessarily the antiparticle - for example, a W-boson can decay to an electron and a anti-neutrino.
    This also answers the second question - In principle, you can create a single boson (for example a W-Boson from an electron and anti-neutrino. However, usually you'll need some other particle to balance energy and momentum, for example when an electron and a positron annihilate, they form two photons, not one.
  5. Jan 19, 2013 #4
    I meant 'creation'... Zapperz

    Sonderval: yeah u understood my ques... "a W-boson can decay to an electron and a anti-neutrino." but that's the case of beta decay... Suppose someone asks me what's the least energy required to create electron... I will say 2mc^2 as I have to create a positron too... But if someone only says fundamental particle,what should I say? E or 2E?
  6. Jan 19, 2013 #5
    Somebody correct me if I'm wrong, but conservation of charge is what comes into play here. If you had Q=0 and the create a single electron (without the oppositely charged positron) Q is no longer conserved in that process and therefore not allowed.

    Particle interactions cannot violate conservation laws and there are a lot of them ;-)
  7. Jan 19, 2013 #6
    What's wrong with beta-decay?
    The minimum energy of course depends on the chosen reference frame. So if you create a virtual W-boson by whatever process that decays into an electron and a neutrino, the minimum energy should be the mass energy of the electron plus that of the neutrino plus the necessary kinetic energy to balance the momenta - all taken in the rest frame of the center of mass of the final particles.
    I'm not sure that's a very meaningful number, though.
  8. Jan 19, 2013 #7
    Well if I ask you what's the least energy required to create a fundamental particle of mass m,what would be ur answer? mc^2 or 2mc^2
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