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B Dark matter variations on Earth

  1. Sep 1, 2017 #41

    Drakkith

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    QED does model electrostatic interactions using virtual photons though, and Feynman diagrams incorporate both real and virtual particles if I remember correctly.
     
  2. Sep 1, 2017 #42

    ohwilleke

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    A field is just photons. If there is nothing to transmit electromagnetic interactions, there is no electromagnetism. Coulomb's law absolutely requires photons in QED.
     
  3. Sep 1, 2017 #43
    Do you see any from a static charge? Where are they? What frequency? Virtual perhaps but ... long story ...
     
  4. Sep 2, 2017 #44

    mfb

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    Photons have to be possible to have static fields in QFT, even if there are no photons flying around.
     
  5. Nov 15, 2017 at 5:43 PM #45
    What if there were dark matter that interacts only with photons and concentrated in the sun and it doesn't interact with any other particles.. does it mean this dark matter species doesn't interact with the weak force but only gravity and with photons.. what are these called then and isn't there any paper that mentions this?
     
  6. Nov 15, 2017 at 6:54 PM #46

    Drakkith

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    Please stick to real science and avoid speculation such as this. We can't hope to answer every "what if..." scenario that people come up with.
     
  7. Nov 15, 2017 at 7:11 PM #47
    I mean why does dark matter obey the weak interaction.. does it really interact with the weak force? Why not just gravity?
     
  8. Nov 15, 2017 at 7:11 PM #48

    Drakkith

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    As far as we know, it doesn't. It only interacts via gravity.
     
  9. Nov 16, 2017 at 3:09 AM #49

    mfb

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    We know it doesn’t interact with photons, otherwise we would see it.
    For particles that interact only via gravity it is unclear how they could have been produced in the right amount in the early universe.
     
  10. Nov 16, 2017 at 3:13 AM #50
    I thought WIMP interacts via the weak force.. i thought anything that comes from Supersymmetry should interact at least the weak force.. but if it only interacts via gravity.. how come experiments reported WIMP null results when they can't be detected except by gravity?
     
  11. Nov 16, 2017 at 6:47 AM #51

    mfb

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    By definition, yes (WI in WIMP). That doesn’t mean dark matter has to consist of WIMPs.
    Additional particles don’t have to participate in the weak interaction, it is just likely.
    Null results of detectors looking for weak interactions are perfectly consistent with particles with no weak interaction.
     
  12. Nov 16, 2017 at 9:59 AM #52

    ohwilleke

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    Particles with no weak, strong or EM interactions are not only perfectly consistent with the non-detection of dark matter in direct detection experiments and the non-detection of DM at the LHC. They are also consistent with the absence of any compelling DM annihilation signature. So, while non-detection of DM in those channels is parameter bounding for DM theories, it certainly doesn't rule out DM that is "sterile" (i.e. that only interacts via gravity) or DM that only interacts with other DM in addition to gravity.

    The trouble is that the amount of correlation between inferred DM distributions and baryonic matter distributions is too tight to be explained by gravity alone and the shape of the DM distributions aren't what we would theoretically predict if DM was truly sterile or only interacted with other DM. So, truly sterile DM or DM that only interacts with other DM isn't enough to explain the phenomenology.

    This leaves you looking for a fifth force that predominantly governs DM-ordinary matter interactions (and possibly also DM to DM interactions), such as the paper described below, in a dark matter particle theory.

    Andres Olivares-Del Campo, et al., "Dark matter-neutrino interactions through the lens of their cosmological implications" (November 14 2017).
     
  13. Nov 17, 2017 at 2:12 PM #53
    May I know what this "correlation" you were referring to that indicates the amount of correlation between inferred DM distributions and baryonic matter distributions is too tight to be explained by gravity alone? Some references directly about it perhaps? Thank you

     
  14. Nov 17, 2017 at 2:39 PM #54
    It says it solves some problems for CDM also it can simulate on large scales.

    But in general it doesnt seem to me a perfect candidate to understand the general description of CDM. As ohwilleke pointed out we need a new model and maybe even a new force.
     
    Last edited: Nov 17, 2017 at 3:15 PM
  15. Nov 18, 2017 at 12:40 AM #55

    ohwilleke

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    Some references can be found in thIs post. I don't specifically mention it there but collisionless bosonic dark matter models also don't work.
     
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