
Dark matter may be hiding in a hidden sector - dnetesn
http://phys.org/news/2016-11-dark-hidden-sector.html
======
maxander
The article revolves around the concept of hidden or visible "sectors," and
never seems to explain what kind of thing thee actually are. Does anyone have
the expertise to clarify?

~~~
mtnygard
Disclaimer: not a string theorist.

In examining the behavior of superstrings, we are concerned with modes of
oscillation. As with ordinary strings, the possible oscillations are
determined by the boundary conditions on the string. E.g., both ends of the
string can be fixed; both ends can be variable; one end can be fixed, one
variable.

One dimensional strings in a three dimensional space really just have a couple
of possible conditions.

Superstrings oscillate through as many as 10 dimensions. That means there are
many more possible boundary conditions. They come in groups. As an analogy, if
a dimension ranges from 0.0 to 1.0, the string behaves pretty much the same
regardless of whether its end is fixed at 0.5 or 0.6. What matters is that it
is fixed. We can group the "fixed endpoint" conditions together.

The collection of boundary conditions on a superstring defines a "sector".

The "hidden sectors" is the part I'm less clear on. I think that refers to the
many combinations of boundary conditions that would produce a string theory
that we simply can't observe. I.e., all the strings we see as bosons,
fermions, charge carriers, etc. share some sector. But the underlying math
allows other string theories to exist. They are internally consistent but
would result in particles we could not observe.

And, of course, 100% of this is based on string theory which is, thus far,
unproven.

