Physicists Think We Might Have a New, Exciting Dark Matter Candidate (sciencealert.com) 33
Science Alert reports:
The candidate culprit is a recently discovered subatomic particle called a d-star hexaquark. And in the primordial darkness following the Big Bang, it could have come together to create dark matter... explained nuclear physicist Daniel Watts of the University of York in the UK. "Our first calculations indicate that condensates of d-stars are a feasible new candidate for dark matter. This new result is particularly exciting since it doesn't require any concepts that are new to physics...."
When six quarks combine, this creates a type of particle called a dibaryon, or hexaquark. We haven't actually observed many of these at all. The d-star hexaquark, described in 2014, was the first non-trivial detection... If such a gas of d-star hexaquarks was floating around in the early Universe as it cooled in the wake of the Big Bang, according to the team's modelling, it could come together to form Bose-Einstein condensates. And those condensates could be what we now call dark matter.
When six quarks combine, this creates a type of particle called a dibaryon, or hexaquark. We haven't actually observed many of these at all. The d-star hexaquark, described in 2014, was the first non-trivial detection... If such a gas of d-star hexaquarks was floating around in the early Universe as it cooled in the wake of the Big Bang, according to the team's modelling, it could come together to form Bose-Einstein condensates. And those condensates could be what we now call dark matter.
"Exciting" (Score:4, Insightful)
This new result is particularly exciting since it doesn't require any concepts that are new to physics
Has the meaning of exciting changed?
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It's when people realize that you must insert
to get a new line on /.
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My other car is dark matter.
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Re: "Exciting" (Score:1)
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So is mine. Except mine is special, the gravity field only sucks in money, nothing else :(
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So are you saying Black is Dark?
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Speak for yourself.
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Exciting Dark Matter Candidate
Has the meaning of exciting changed?
Well, just a few weeks back, folks were talking about the possibility of a "Dark Horse Candidate [wikipedia.org]".
Biden vs. Sanders looks kinda sorta boring, so a new Dark Matter Candidate is very exciting indeed.
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Exciting in the sense that not requiring new physics removes a lot of ifs and maybes. Not all of them, by a long shot, but a lot.
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What is really happening though, is the deeper they look the smaller they find. So how small could a mass less particle become and how would you detect it except when it cluster together to express mass. Barely a century into real science and the still routinely claim to find all there is to find. Why would there be any limit on particle size, differentiating between particles that express mass and particles that do not express mass, except as clusters of particles and then drop below the speed of gravity.
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Translation (Score:1)
"We haven't actually observed many of these at all." : This is a purely theoretical particle that has never been observed but I want to imply that it's real.
Re:Translation (Score:4, Interesting)
Doesn't make sense (Score:5, Interesting)
If such a gas of d-star hexaquarks was floating around in the early Universe as it cooled in the wake of the Big Bang, according to the team's modelling, it could come together to form Bose-Einstein condensates. And those condensates could be what we now call dark matter.
This doesn't make much sense. Bose-Einstein condensates are cold. The early universe was very hot: the universe was around 370,000 years old when the average temperature dropped below 3000 K. We have direct evidence from the CMBR that the universe had the same proportion of dark matter then and now. In fact, that's what cinched the "cold dark matter" theory, as MOND and MACHOs didn't predict that.
So, whatever dark matter is, it's unbothered by temperatures of 3000 K. Doesn't sound much like a Bose-Einstein condensate. Presumably the authors of the paper know this, and it's just TFS that's confused.
Re:Doesn't make sense (Score:5, Informative)
It gets much worse (Score:5, Interesting)
The problem with this is that it requires an insanely high production rate of dibaryons in the early universe - the paper has their production rate exceeding the production rate of normal baryons several times over when the Quark-Gluon plasma (QGP) condenses. However, we have produced QGP in heavy-ion collisions at the LHC and yet (as far as I know) no LHC experiment has seen any evidence of dibaryon production despite the prediction that it should exceed normal baryon production many times over. There may not be enough to make the BEC but the dibaryon production and then decay should surely be noticeable given the predicted rates exceed the observed baryon flux many times over. This also has potential consequences for nucleosynthesis in the early universe which is one of the triumphs of the Big Bang model but I could not see this discussed anywhere in the paper.
Then there is the question about why this BEC would be Dark Matter. The paper claims that the highly electrically charged condensate would attract electrons and become neutral and may be very hard to observe astronomically today. However, they completely fail to discuss its interactions with the plasma that filled the universe and which gave rise to the Cosmic Microwave Background. If they existed why were these highly charged (but massive) "nuclei" not bound to that plasma? While their mass would be far larger than ordinary nuclei their charge is also similarly much higher. A key property of Dark Matter is that it was completely decoupled from this plasma which is why the CMB shows fine-scale temperature variations.
It's a neat idea to think about but if you want people to take a new model of Dark Matter seriously you do need to show how it is consistent with current data from particle physics and cosmology, not just visible light astronomy. It's possible that there are good answers to the questions above but these should have been addressed in the paper.
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The paper claims that the highly electrically charged condensate would attract electrons and become neutral and may be very hard to observe astronomically today. However, they completely fail to discuss its interactions with the plasma that filled the universe and which gave rise to the Cosmic Microwave Background. If they existed why were these highly charged (but massive) "nuclei" not bound to that plasma? While their mass would be far larger than ordinary nuclei their charge is also similarly much higher. A key property of Dark Matter is that it was completely decoupled from this plasma which is why the CMB shows fine-scale temperature variations.
It's a neat idea to think about but if you want people to take a new model of Dark Matter seriously you do need to show how it is consistent with current data from particle physics and cosmology, not just visible light astronomy. It's possible that there are good answers to the questions above but these should have been addressed in the paper.
Well put. Plus, anything that has bound electrons can have inelastic collisions, and so simply couldn't produce the spherical dark matter halos needed to explain galaxy rotation rates.
...and why not Deuterium? (Score:2)
Bose-Einstein condensates throughout the universe (Score:3)
Re:Bose-Einstein condensates throughout the univer (Score:5, Funny)
We just have to figure out how to use it.
We already know how: Put on a miniskirt, stick a funny metal cylinder in your left ear, and twiddle some illuminated plastic rectangles.
If you run into any issues, reverse the polarity.
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There is nothing to indicate that B-E condensate interactions of this sort violate Bell's inequality or show any non-locality.
Interaction cross section? (Score:3)
Probably just my ignorance, but why wouldn't these interact thought the strong force with other matter? That would seem to suggest a cross section far to high to be consistent with dark matter modes. Anyone understand why these would be nearly non-interacting?
And in other news (Score:1)
At least bunnies are a real thing, and not just invented ad-hoc out of nothing because a cherished belief about gravity being the only major force in the universe was falsified by evidence.
What is the halflife estimate? (Score:1)
Read the article quickly. It did not define what the stability meant in terms of halflife and decay products. This kind of info is key to determining how stable it is and if it can be a DM candidate, it just said "1000s or millions"
I like the results, and did not find any errors in a 1st glance, however that is a key followup and could even potentially be explored at the LHC before looking for signatures of it's decay.
Nice new idea... article needs a drop more work, and lov