About strings ?

[1123581321]

I was wondering what anti-strings are..

[ajb]

I don't think there is such a notion, or at least not one I have come across.

 

The states of an excited string correspond to particle and anti-particle states. So, the excitations describe particles and antiparticles. The string is still "just a string". You have "right and left movers" in string theory, these sectors do not talk to each other. They are not identified as particles and anti-particles.

 

A similar thing occurs in quantum field theory, you can decompose the excitations of the field into positive and negative frequencies, which you do identify with particles and anti-particles but one does not really talk of a field and and anti-field (in this context. There is a notion of an anti-field but this is a very different notion).

[1123581321]

I was wondering also, with bosonic string theory - the original model. Is bosonic referring to the string itself or just the particle for which it is associated with.. in its case, the boson.

[ajb]

Both.

 

The bosonic string is described classically in terms of commuting variables. Essentially one is thinking of embedding a 2-d world sheet in some higher dimensional bulk. You can think in terms of a 1+1 dimensional bosonic field theory. (Or bosonic sigma models) Such a string cannot describe the fermionic degrees of freedom as required for any reasonable phenomenologically useful model.

[1123581321]

How many string theories are there ?

[ajb]

Understood via perturbation theory 1 bosonic and 5 supersymmetric.

 

M-theory understands the supersymmetric string theories as expansions about different limits. Non-perturbatively there are (or should be?) string theories "in between" these limits.

[johnmarsh]

i new for this forum but i understand ur question but i really not know whats meaning for this

[ajb]

i new for this forum but i understand ur question but i really not know whats meaning for this

 

Welcome to the forum.

 

I don't think there is any notion of an anti-string. I have not come across anyone talking about anti-strings for sure.