

Particle detector finds hints of dark matter in space - 2510c39011c5
http://newsoffice.mit.edu/2014/alpha-magnetic-spectrometer-detects-positrons-0918

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jeroen94704
From the article: "The new AMS results may ultimately help scientists narrow
in on the origin and features of dark matter"

So yet another link-bait headline.

~~~
simon_
Maybe, but I would wait to hear from a physicist. When I was a student, one of
the most important papers one year was about a dark matter (WIMP) detector
that failed to find anything, thus "trimming the parameter space" for what the
particles might look like. If this is a genuine clue, it's probably very
exciting.

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3327
This is a surprisingly Vague article for MIT press. I understand its just the
press release and not the white paper but could there not be a little more
detail? Perhaps Interns are writing it could it not have a bit more content be
it data, opinion from scientist, the leading theory in the area.

Its exciting stuff and not a dead end article, so little progress has been
made in this field and the unknowns are so fast that eve a glimpse is
interesting.

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rubyn00bie
Hmm... whenever I see this [articles about dark matter or dark energy]
nowadays I think back to something Dr. Neil deGrasse Tyson said on the subject
along the lines of "We're calling it Dark Matter or Dark Energy because can we
measure it (or rather the fact that we're missing a huge chunk of it), but
that doesn't mean it's 'dark' or even 'matter' or even one single thing."

It's cool to hear about breakthroughs on the subject but as someone else said,
at this point this article feels more like link-bait than anything concrete.

Maybe it's just some folks who are incredibly stoked wanting to share before
they have their ducks-in-row. So I'm not trying to say it's intentional.

I'm just hungry for new information, and excited about it, so when it's not
all there I'm disappointed. Nerd problems, haha.

~~~
inclemnet
> but that doesn't mean it's 'dark' or even 'matter' or even one single thing

An important addendum to this is that it really does look an awful lot like
matter that happens to be dark...or to be more specific, electromagnetically
inert.

That's not to say it has to be, of course we don't know for sure, but I see a
lot of people on the internet apparently quite certain it's not matter at all
- often for not very good reasons, or via arguments that aren't remotely that
strong.

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ISL
CERN press release: [http://press.web.cern.ch/press-releases/2014/09/latest-
measu...](http://press.web.cern.ch/press-releases/2014/09/latest-measurements-
ams-experiment-unveil-new-territories-flux-cosmic-rays#overlay-context=)

The PRLs:
[http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.113...](http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.113.121101)

[http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.113...](http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.113.121102)

Physics News: [http://physics.aps.org/synopsis-
for/10.1103/PhysRevLett.113....](http://physics.aps.org/synopsis-
for/10.1103/PhysRevLett.113.121102)

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essive
Very strange to see this article posted now. This news from the AMS is over a
year old. And clearly, there is considerable debate whether the positron
excess is from dark matter particle annihilation or from nearby pulsars. There
are many papers on the subject - here is just one example that explains some
of the issues -
[http://arxiv.org/pdf/1304.1840.pdf](http://arxiv.org/pdf/1304.1840.pdf) (PS -
I am an astronomy graduate student).

~~~
ISL
This article concerns a new data release from AMS -- 70% more statistics and a
much wider energy range.

In the past, they've been careful to avoid saying whether or not the positron
fraction flattens/rolls over at higher energy. These papers now give support
to that conclusion, at moderate confidence levels.

~~~
essive
Excellent callout and my mistake missing the point on the wider energy range
and the rollover. Thank you! The additional data will help the determination
of dark matter vs. pulsars as the positron source.

"To determine if the observed new phenomenon is from dark matter or from
astrophysical sources such as pulsars, AMS is now[sic] making measurements to
determine the rate of decrease at which the positron fraction falls beyond the
turning point (item 5), as well as to determine the antiproton fraction (the
ratio of antiprotons to protons plus anti-protons). These will be reported in
future publications."

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danbruc
Compatible with a dark matter particle on the order of 1 TeV - now just turn
LHC back on, find a matching supersymmetric particle and give a welcome party
for the 5th dimension.

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3rd3
What would the 5th dimension be?

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danbruc
I am not a physicist, therefore this may be complete nonsense. Anyway, as far
as I understand it, supersymmetry (all models or only some, I have no idea)
adds a new dimension (with non-commutative coordinates?) and when a particle
moves along this dimension it turns from a fermion into a boson or vice versa.
You take a electron and move it a bit along this dimension and it turns into a
photon, you move it back and it becomes an electron again. (Electron and
photon are not superpartners, the electron would actually become a selectron,
the photon a photino with the photino being one of the candidates for dark
matter.)

~~~
orbifold
I've taken courses on supersymmetry and string theory and this is mostly
incorrect. The details are fairly complicated, but the general idea is that
there are a few essentially unique supersymmetric theories in 10 dimensions
that can be "compactified" to a vast variety of effective theories in four
dimensions. From a purely phenomenological point of view that can be ignored
however and people have come up with various supersymmetric extensions of the
standard model of particle physics in four dimensions going by names like MSSM
(minimal supersymmetric standard model), basically introducing aditional
superpartners of known particles by hand (like the selectron and photino you
mentioned) and "completing" the model by computing the deficit for it to be
supersymmetric. Those completions are not unique and can be distinguished by
the energy scales they introduce new particles at. One major motivation is to
constrain the running of the Higgs mass, which sets a natural upper bound for
the expected masses of supersymmetric particles to be found. Those bounds have
already almost been excluded by the current data, which is scary or exiting
depending on who you ask.

