Question

In: Physics

Most string theory compactifications analyzed so far have as backgrounds a conformal field theory corresponding to...

Most string theory compactifications analyzed so far have as backgrounds a conformal field theory corresponding to a nonlinear sigma model with a Calabi-Yau target space, or some relatively classical background, possibly with orbifolding. But as long as the central charge of the Virasoro algebra is right, and worldsheet superconformal symmetry is respected, any other superconformal field theory will do just as well. Why haven't string theorists looked at such models more often?

Solutions

Expert Solution

Such models have been looked at in a fair amount of detail. For example, "Gepner" models are constructed by tensoring together superconformal minimal models. Asymmetric orbifolds which have the correct superconformal worldsheet symmetry have also been constructed. The problem is that if you break spacetime susy when you construct these theories directly as SCFTs you typically have tachyons and no good way to figure out the ground state of the system. If you preserve spacetime supersymmetry then many (all?) of the Gepner models turn out to describe special points in the moduli space of Calabi-Yau compactifications. So in this case at least, sigma-models with CY target end up being the more general construction. Some of the asymmetric orbifold constructions are not equivalent to CY as far as I know, but they are quite specialized and I don't know of any that have very realistic phenomenology. So basically the answer is that people tend to focus on the CY case because it is richer and you can do more with it. Of course there are probably some interesting constructions based on the SCFT approach you are asking about that have not been found yet. For example, I don't know of any Gepner model constructions of G2 holonomy compactifications (I'd be happy to be corrected if these do in fact exist).


Related Solutions

String field theory (in which string theory undergoes "second quantization") seems to reside in the backwaters...
String field theory (in which string theory undergoes "second quantization") seems to reside in the backwaters of discussions of string theory. What does second quantization mean in the context of a theory that doesn't have Feynman diagrams with point-like vertices? What would a creation or annihilation operator do in the context of string field theory? Does string field theory provide a context in which (a) certain quantities are more easily calculated or (b) certain concepts become less opaque?
I have solved most of question and the answers I have so far are correct, I...
I have solved most of question and the answers I have so far are correct, I just need help finding out the lower bound and upper bound (All answers were generated using 1,000 trials and native Excel functionality.) Galaxy Co. distributes wireless routers to Internet service providers. Galaxy procures each router for $75 from its supplier and sells each router for $125. Monthly demand for the router is a normal random variable with a mean of 100 units and a...
So far we far we have been discussing the advantages of HIT, but have not considered...
So far we far we have been discussing the advantages of HIT, but have not considered its disadvantages. Discuss at least three (3) of the disadvantages or challenges that can be encountered by adoption of the HIT, such as EHR (Electronic Health Record) or HIE (health Information Exchange).
Hi, I have this code so far and need to modify it so that the output...
Hi, I have this code so far and need to modify it so that the output does not print something like 2x^0 but instead will just print 2. Currently it prints 2x^0. I also am having a problem with the output of Polynomial 1 - Polynomial 2. If both coefficient values for the polynomials are equal instead of Polynomial 1 - Polynomial 2 = 0 it outputs nothing. Just Polynomial 1 - Polynomial 2 = For example if I input...
Great answers so far! And let's not forget that the balance sheet shows our most important...
Great answers so far! And let's not forget that the balance sheet shows our most important basic accounting equation. Assets=Liabilities + Owners Equity. This equation and keeping it in balance seems to be the main focus of the staff accountant. I want to also discussion the relationship of the balance sheet to the other financials statements. What order must we prepare the financial statements in and why? How are the other statements (Income Statement, Cashflows, Statement of RE) shown on...
Why is Maslow or Rogers theory so important to the field of psychology today? What would...
Why is Maslow or Rogers theory so important to the field of psychology today? What would psychology be missing without Maslow or Theory? (500 - 750 words)
In JAVA PLEASE With the mathematics you have studied so far in your education you have...
In JAVA PLEASE With the mathematics you have studied so far in your education you have worked with polynomials. Polynomials are used to describe curves of various types; people use them in the real world to graph curves. For example, roller coaster designers may use polynomials to describe the curves in their rides. Polynomials appear in many areas of mathematics and science. Write a program which finds an approximate solution to an equation f(x) = 0 for some function f....
In JAVA, please With the mathematics you have studied so far in your education you have...
In JAVA, please With the mathematics you have studied so far in your education you have worked with polynomials. Polynomials are used to describe curves of various types; people use them in the real world to graph curves. For example, roller coaster designers may use polynomials to describe the curves in their rides. Polynomials appear in many areas of mathematics and science. Write a program which finds an approximate solution to an equation f(x) = 0 for some function f....
Reflect on and relate to what you have learned so far in the course with respect...
Reflect on and relate to what you have learned so far in the course with respect to your ability to calculate gross domestic product and its impact on the economy’s business cycle, unemployment, and inflation; using gross domestic product formulate recommendations for a government’s role in achieving full employment in an economy.
what are the key historical event that have shaped the accounting profession so far
what are the key historical event that have shaped the accounting profession so far
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT