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MTd2
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Suppose we detect a new force whose gauge group would require a SU(N) rep. What would be the smallest one that could not fit within string theory?
tom.stoer said:What about E(N) with N>8?
It does exist, but it turns out that it becomes an infinite-dimensional Kac-Moody algebra.suprised said:Lol, that doesn't exist.
noKevin_Axion said:surprised, tom.stoer is referring to the Infinite Simple Lie Groups: An, Bn, Cn, Dn.
Kevin_Axion said:surprised, tom.stoer is referring to the Infinite Simple Lie Groups: An, Bn, Cn, Dn.
tom.stoer said:It does exist, but it turns out that it becomes an infinite-dimensional Kac-Moody algebra.
This is just the situation is string theory; I understand.suprised said:The "extra" gauge fields are not massless... the structure of a KM algebra is like this: at the "bottom" there is an ordinary algebra, which correspond to the massless gauge bosons. Then there is an infinite sequence of massive "excitations" that can be thought of as a cone over this algebra. In string theory those correspond to massive excitation modes of the gauge bosons; you always get the full tower and nothing less (I had alluded to this earlier when I mentioned somewhere else that string theory is extremely finely tuned and fixed in the massive sector). This is simply because the whole thing represents a loop algebra and this is nothing but the stringy generalization of gauge symmetry.
Yes, this is what I am asking; why is such a theory sick?suprised said:What you seem to ask for is a setup where all the infinitely many roots would correspond to massless gauge bosons. That is obviously a sick gauge theory.
tom.stoer said:I mean - yes - you would create infinitly many massless degrees of freedom, but perhaps you can generate infinitly many constraints as well and get rid of some degrees of freedom; look at the center symmetric phase in QCD where the theory somehow reduces itself to the center of the gauge group (don't take this too literally :-)
This is the swampland-discussion.MTd2 said:So, there is no gauge theory that cannot be described by string theory at some limit, right?
I have not read about those in a while, but I do remember explicit brane stacking constructions of SU(N) were consistent. I should check when I come home, but it seem to me this is also in Zwiebach's book.MTd2 said:But humanino said it could accommodate for any SU(N)...
MTd2 said:So, there is no gauge theory that cannot be described by string theory at some limit, right?
MTd2 said:But humanino said it could accommodate for any SU(N)...
suprised said:You can't put an arbitrary number of branes or fluxes in the theory because in a true "compact" compactification, the flux must go somewhere. This is a "global" constraint that ultimately arises when you like to consistently couple the theory to gravity.
MTd2 said:I tried to read about fluxes in m theory, but I couldn't keep what I read in my mind. Perhaps discussing here will help me, ok?
1. What is string theory and why is it important?
String theory is a theoretical framework that attempts to reconcile the conflicting theories of quantum mechanics and general relativity. It proposes that all particles in the universe are made up of tiny strings vibrating at different frequencies, rather than being point-like particles. It is important because it has the potential to unify all known physical forces and provide a deeper understanding of the fundamental nature of the universe.
2. Can string theory be proven or disproven?At this point, string theory remains a theoretical framework and has not yet been proven or disproven. It is still an active area of research and there is ongoing debate and exploration into its validity.
3. What is the extra force that could rule out string theory?The extra force that could potentially rule out string theory is a force that violates the fundamental principles of the theory. This could be a force that is not accounted for in the framework, or a force that produces results that are inconsistent with the predictions of string theory.
4. Are there any current experiments or observations that could provide evidence against string theory?There are ongoing experiments and observations that could potentially provide evidence against string theory, but at this point, there is no conclusive evidence. Some proposed experiments include high energy particle collisions or observations of the cosmic microwave background radiation.
5. How would ruling out string theory impact our understanding of the universe?If string theory were to be ruled out, it would mean that we would need to explore alternative theories and frameworks to understand the fundamental nature of the universe. It would also mean that we would need to reassess our understanding of the laws of physics and how they govern the behavior of particles and forces in the universe.