A more model independent argument (which does have loopholes) goes as
follows. The weaker WIMPS interact with themselves and with baryons, the
sooner after the Big Bang they decouple, leading to a higher present-day
abundance. Then with the present-day abundance fixed, this implies
limits on the parameters describing WIMPS. And it becomes more and more
difficult to accommodate for WIMS with smaller and smaller small
cross-sections. But dark matter that has extremely weak interactions and
self-interactions would never have been in thermal equilibrium, which is
a possible loophole out of this no-go argument.
Saibal
On 10-08-2023 01:42, Jesse Mazer wrote:
Does the idea that colliders should have already found WIMPs depend on
the "naturalness" idea at
https://en.wikipedia.org/wiki/Naturalness_(physics) which requires
supersymmetric particles at those energies in order to solve the
"hierarchy problem", or are there independent reasons to think that if
WIMPs existed they should already have been found? I've read that
those who endorse the string theory "landscape" idea see anthropic
fine-tuning as an alternative to naturalness and thus didn't predict
that supersymmetric particles would likely be found at LHC energies,
for example Leonard Susskind's 2004 paper at
https://arxiv.org/abs/hep-ph/0406197v1 said the following on pages
1-2:
'If the Landscape and the Discretuum are real, the idea of naturalness
must be replaced with something more appropriate. I will adopt the
following tentative replacement: First eliminate all vacua which do
not allow intelligent life to evolve. Here we need to make some
guesses. I’ll guess that life cannot exist in the cores of stars,
cold interstellar dust clouds or on planets rich in silicon but poor
in carbon. I’ll also guess that black holes, red giants and pulsars
are not intelligent.
'Next scan the remaining fraction of vacua for various properties. If
the property in question is common among these “anthropically
acceptable” vacua then the property is natural. By common I mean
that some non-negligible fraction of the vacua have the required
property. If however, the property is very rare, even among this
restricted class, then it should be deemed unnatural. Of course there
is no guarantee that we are not exceptional, even among the small
fraction of anthropically acceptable environments. It is in the nature
of statistical arguments that rare exceptions can and do occur.
Michael Douglas has advocated essentially the same definition although
he prefers to avoid the use of the word anthropic wherever possible,
and substitute “phenomenologically acceptable”. We have both
attempted to address the following question: Are the vacua with
anthropically small enough cosmological constants and Higgs masses,
numerically dominated by low energy supersymmetry or by supersymmetry
breaking at very high energy scales [8][7]? In other words is low
energy supersymmetry breaking natural? My conclusion–I won’t
attempt to speak for Douglas–is that the most numerous “acceptable
vacua” do not have low energy supersymmetry. Phenomenological
supersymmetry appears to be unnatural.'
On Sat, Aug 5, 2023 at 5:26 PM Lawrence Crowell
<goldenfieldquaterni...@gmail.com> wrote:
One weakness with this idea is it depends upon WIMP theory. This is
where the DM particles are weak interacting and Majorana. They are
their own anti-particle as a result annihilate themselves. The
problem is that detectors means to find WIMPS have come up with
nothing. DM appears to exist, but it may not be a weakly interacting
particle or WIMP.
LC
On Sunday, July 16, 2023 at 6:58:19 AM UTC-5 John Clark wrote:
As early as 2012 scientists predicted that the Hubble telescope
would see something they called a "Dark Star".
Observing supermassive dark stars with James Webb Space Telescope
[1]
They theorized in the early universe Dark Matter, whatever it is,
must've been much more densely concentrated than it is today, and
if Dark Matter particles are their own antiparticles as many think
then their annihilation could provide a heat source, they could
keeping star in thermal and hydrodynamic equilibrium and prevent
it from collapsing. They hypothesized something they called a
"Dark Star '', it would be a star with a million times the mass of
the sun and would be composed almost entirely of hydrogen and
helium but with 0.1% Dark Matter. A Dark Star would not be dark
but would be 10 billion times as bright as the sun and be powered
by dark matter not nuclear fusion.
Astronomers were puzzled by pictures taken with the James Webb
telescope that they interpreted to be bright galaxies just 320
million years after the Big Bang that were much brighter than most
expected them to be that early in the universe, a recent paper by
the same people that theorized existence of Dark Stars claim they
could solve this puzzle. They claim 3 of the most distant objects
that the Webb telescope has seen are point sources, as you'd
expect from a Dark Star, and their spectrum is consistent with
what they predicted a Dark Star should look like. With a longer
exposure and a more detailed spectrum, Webb should be able to tell
for sure if it's a single Dark Star or an early galaxy made up of
tens of millions of population 3 stars.
Supermassive Dark Star candidates seen by JWST [2]
John K Clark See what's on my new list at Extropolis [3]
3vy
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Links:
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[1]
https://academic.oup.com/mnras/article/422/3/2164/1043351?login=false
[2] https://www.pnas.org/doi/10.1073/pnas.2305762120
[3] https://groups.google.com/g/extropolis
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