Tagged Questions
8
votes
0answers
121 views
Compactifying on a circle and the exchange of R and NS sectors
I've noticed a general phenomenon in compactifying on a circle where if you start with, say, an NS field, then the KK fields with an index along the circle will be in the R sector, and those without ...
1
vote
0answers
54 views
Folded and/or compacted dimensions in M-theory?
I've on many occasions that there are various numbers of 'extra' dimensions above the 4th. However, I've heard that they are 'compacted' or 'folded' tightly and unimaginably small. Now, as I ...
3
votes
2answers
293 views
How can one imagine curled up dimensions?
Actually I'm learning String Theory, and one of its proposals is that there are actually 25+1 dimensions of which only 3+1 are visible to us-- and the remaining are curled up. However, superstring ...
4
votes
1answer
73 views
What is the connection between extra dimensions in Kaluza-Klein type theories and those in string theories?
This follows to some extent from a question I asked previously about the flaws of Kaluza-Klein theories.
It appears to me that Kaluza-Klein theories attach additional dimensions to spacetime that are ...
3
votes
2answers
205 views
Measuring extra-dimensions
I have read and heard in a number of places that extra dimension might be as big as $x$ mm. What I'm wondering is the following:
How is length assigned to these extra dimensions?
I mean you can ...
2
votes
3answers
202 views
Tachyonic complex structure directions in flux vacua
In flux compactifications to 4D, e.g. Type IIB on a CY orientifold $X$, one uses fluxes to stabilize the axio-dilaton $\tau$ and the complex structure moduli $z_a$ - the periods of the holomorphic ...
8
votes
3answers
290 views
Question about associative 3-cycles on G2 manifolds
Let $X$ be a manifold with $G_2$ holonomy and $\Phi$ be the fundamental associative 3-form on $X$. Let $*\Phi$ be the dual co-associative 4-form on $X$. Now consider a particular associative 3-cycle ...
4
votes
3answers
316 views
Why (in relatively non-technical terms) are Calabi-Yau manifolds favored for compactified dimensions in string theory?
I was hoping for an answer in general terms avoiding things like holonomy, Chern classes, Kahler manifolds, fibre bundles and terms of similar ilk. Simply, what are the compelling reasons for ...
8
votes
2answers
319 views
Heterotic string as worldvolume theory of two coincident 9-branes in 27 dimensions?
The heterotic string is a combination of right-moving excitations from a D=10 superstring and left-moving excitations from a D=26 bosonic string, with the left-movers behaving as if the extra 16 ...
4
votes
2answers
320 views
T-duality approaches
The textbook approach to explaining T-dualities is to show that a type of T-duality transformation "inverts the radius of the circle, that is, it maps $R\rightarrow\tilde{R} = \alpha'/R$ and it ...
