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A Supersymmetry and the EM Force

  1. Dec 10, 2017 #1
    (This is easy for you folks that know SUSY.) I know in SUSY the agent of the EM force is the photino (a spin 1/2 fermion). The EM force that we all learned about in JD Jackson (and the QED version in Sakurai) has the photon (a boson) as the agent of force. Is the SUSY version of E&M, and the QED version of E&M equivalent to the Jackson/SakuraI of E&M? Do I just write down the same Maxwell equations for "non-SUSY" and SUSY applications?
  2. jcsd
  3. Dec 10, 2017 #2
    In supersymmetric QED, the photon is still the quantum of electromagnetism. The photino, being a fermion, is essentially just an extra kind of matter.
  4. Dec 11, 2017 #3
    Thank you for your very quick response.
  5. Dec 11, 2017 #4
    A follow up question on the photino. I assume the photino travels at the speed of light. If that is true, why haven't we ever detected a photino? Could it be that only pure SUSY particles (not hybrids consisting of at least one quark and at least one square) produce photinos?
  6. Dec 11, 2017 #5


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    The photino would have been seen long ago if it was massless. Instead bc super symmetry must be broken it acquires a mass in some model dependant way depending on how Susy is broken. Bc it shares the same quantum numbers with other neutral Susy partners, it will also typically mix between the different species much like neutrinos do in the standard model, so it doesn’t quite have an independant existence.

    As Mitchell says, it behaves like normal matter, and indeed it behaves very much like a heavy version of the neutrino. Indeed we typically call a photino part of a general class of Susy particles called neutralinos.
  7. Dec 12, 2017 #6
    Mitchell and Haelfax, thank you for your responses. Your comments have raised physics questions in my mind and I need to think about this subject some more. I sure wish I had studied SU-3 and the strong interactions harder when I was in grad school.
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