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Thread: LHC results and dark matter

  1. #1 LHC results and dark matter 
    Forum Bachelors Degree PetTastic's Avatar
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    The latest results from the LHC seem to rule out some forms of super symmetry.

    What does this mean for dark matter detectors?
    Are we still expecting to see radiation from dark matter particle annihilations?
    What about detectors that are looking for direct collisions?


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    There is little relationship between supersymmetry and dark matter. The only connection is that one candidate for dark matter is the neutralino (supersymmetric partner of neutrino).


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    Quote Originally Posted by PetTastic View Post
    The latest results from the LHC seem to rule out some forms of super symmetry.

    What does this mean for dark matter detectors?
    Are we still expecting to see radiation from dark matter particle annihilations?
    What about detectors that are looking for direct collisions?
    It basically means we need to keep looking, and perhaps that supersymmetric particles aren't good candidates for dark matter.
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  5. #4  
    Forum Bachelors Degree PetTastic's Avatar
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    Quote Originally Posted by Markus Hanke View Post

    It basically means we need to keep looking, and perhaps that supersymmetric particles aren't good candidates for dark matter.
    The question is what kind of dark matter detector do we build next?
    The LHC results go some way to explaining why the current detectors turned up empty.
    Last edited by PetTastic; November 15th, 2012 at 09:30 AM. Reason: what -> why
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    seems like the popular candidate for dark matter is still neutrino, though the biggest problem still persists: dark matter covers majority of the mass in this universe while neutrino does not seem to possess any mass at all.

    can someone explain super symmetry? this concept is hard to grasp for me
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    Quote Originally Posted by Halibonga View Post
    seems like the popular candidate for dark matter is still neutrino, though the biggest problem still persists: dark matter covers majority of the mass in this universe while neutrino does not seem to possess any mass at all.

    can someone explain super symmetry? this concept is hard to grasp for me
    You seem to have some misconceptions. The neutrino is not a candidate for dark matter - total mass is estimated as far too small. The neutrino does have a small, but non-zero mass.

    Dark matter - Wikipedia, the free encyclopedia
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    Quote Originally Posted by mathman View Post
    Quote Originally Posted by Halibonga View Post
    seems like the popular candidate for dark matter is still neutrino, though the biggest problem still persists: dark matter covers majority of the mass in this universe while neutrino does not seem to possess any mass at all.

    can someone explain super symmetry? this concept is hard to grasp for me
    You seem to have some misconceptions. The neutrino is not a candidate for dark matter - total mass is estimated as far too small. The neutrino does have a small, but non-zero mass.

    Dark matter - Wikipedia, the free encyclopedia
    well it states in the wiki that dark matter is likely to be partially comprised of neutrinos..
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    Quote Originally Posted by Halibonga View Post
    well it states in the wiki that dark matter is likely to be partially comprised of neutrinos..
    The key is "partially." Neutrinos alone are not anywhere common enough, so the search for dark matter continues.
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    Quote Originally Posted by tk421 View Post
    Quote Originally Posted by Halibonga View Post
    well it states in the wiki that dark matter is likely to be partially comprised of neutrinos..
    The key is "partially." Neutrinos alone are not anywhere common enough, so the search for dark matter continues.
    thats why i said 'candidate' lol, i agree dark matter still have tons of unsolved puzzles in it
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    What are the current bets on dark matter being normal cold baryonic matter?

    Looking through various sites we are only looking for about 6x10-28 kg/cm3 or 6x10-13 kg/km3 average in our galaxy.
    If I have that correct, it is only a small grain of sand per cubic km of interstellar space?
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    Quote Originally Posted by PetTastic View Post
    What are the current bets on dark matter being normal cold baryonic matter?

    Looking through various sites we are only looking for about 6x10-28 kg/cm3 or 6x10-13 kg/km3 average in our galaxy.
    If I have that correct, it is only a small grain of sand per cubic km of interstellar space?
    Based on the ratio of H2 to H1 in the universe (and other observations) there is nowhere enough baryonic matter (cold or otherwise) to account for dark matter.
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    I agree that accepted theory says the baryonic matter should not be there, but with the LHC results only supporting the standard model, what else is left to look for?
    If it was, say iron dust from first/second generation stars, could we detect it?

    Not that I would like that amount of interstellar material to exist as it would make interstellar space flight almost impossible at speed.
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    Quote Originally Posted by PetTastic View Post
    The latest results from the LHC seem to rule out some forms of super symmetry.
    The important word is "some". The LHC results put some constraints on the forms of supersymmetry that are possible, but does not rule it out completely.
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    Quote Originally Posted by Strange View Post
    Quote Originally Posted by PetTastic View Post
    The latest results from the LHC seem to rule out some forms of super symmetry.
    The important word is "some". The LHC results put some constraints on the forms of supersymmetry that are possible, but does not rule it out completely.
    Yes agreed. That is why I said some.

    The problem that I am interested in most, is that the 'some' in question is what our dark matter detectors were looking for.
    If the simplest and lower-end energy supersymmetry particles are unlikely to exist, what do start looking for next?
    If these particles only interact via gravity, or are extremely massive and rear, can we ever prove they exist?
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    Quote Originally Posted by PetTastic View Post
    If it was, say iron dust from first/second generation stars, could we detect it?
    Not that I am an expert on optics, but I would think iron dust ( and pretty much all other baryonic matter too ) would scatter light in certain ways, making it detectable. It appears we detect no interaction between dark matter and EM radiation at all, it seems to have a gravitational effect only.

    If these particles only interact via gravity, or are extremely massive and rear, can we ever prove they exist?
    I think the mere fact that they are thought to exist in large quantities, at "normal" energy levels, and in a stable state, while at the same time not being detected here on earth, appears to place fairly strong constraints on how massive they can possibly be.
    It's an interesting conundrum.
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  17. #16  
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    Quote Originally Posted by Markus Hanke View Post
    Quote Originally Posted by PetTastic View Post
    If it was, say iron dust from first/second generation stars, could we detect it?
    Not that I am an expert on optics, but I would think iron dust ( and pretty much all other baryonic matter too ) would scatter light in certain ways, making it detectable. It appears we detect no interaction between dark matter and EM radiation at all, it seems to have a gravitational effect only.
    Thinking about it, it depends on the size of the particles.
    Fine dust would be heated by the interstellar medium and emit IR, but a tiny iron asteroid per hundred thousand cubic km would be invisible.

    Quote Originally Posted by Markus Hanke View Post
    If these particles only interact via gravity, or are extremely massive and rear, can we ever prove they exist?
    I think the mere fact that they are thought to exist in large quantities, at "normal" energy levels, and in a stable state, while at the same time not being detected here on earth, appears to place fairly strong constraints on how massive they can possibly be.
    It's an interesting conundrum.
    If the most obvious super symmetry contenders can be ruled out, then I think we are looking for heavier but fewer particles.
    If the number of DM particles is lower then there are fewer chances of them colliding and annihilating, so photon based detectors will have a harder job.

    Have I got this correct
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  18. #17  
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    Quote Originally Posted by PetTastic View Post
    If the most obvious super symmetry contenders can be ruled out, then I think we are looking for heavier but fewer particles.
    If the number of DM particles is lower then there are fewer chances of them colliding and annihilating, so photon based detectors will have a harder job.

    Have I got this correct
    Yes you do, but there are two problems :

    1. Very massive particles are generally not stable, but decay after a short time. That does not seem to be the case with DM, unless we are missing something vital.
    2. We don't know if DM interacts with EM radiation at all. If it is not baryonic matter then it's exact properties are anyone's guess at this stage
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  19. #18  
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    Quote Originally Posted by Strange View Post
    The important word is "some". The LHC results put some constraints on the forms of supersymmetry that are possible, but does not rule it out completely.
    As David Gross recently said, super symmetry may not be dead but we are not seeing any signs of life either...
    Strange and Markus Hanke like this.
    As is often the case with technical subjects we are presented with an unfortunate choice: an explanation that is accurate but incomprehensible, or comprehensible but wrong.
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