1123581321 Posted November 22, 2010 Share Posted November 22, 2010 I was wondering what anti-strings are.. Link to comment Share on other sites More sharing options...
ajb Posted November 22, 2010 Share Posted November 22, 2010 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). Link to comment Share on other sites More sharing options...
1123581321 Posted November 22, 2010 Author Share Posted November 22, 2010 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. Link to comment Share on other sites More sharing options...
ajb Posted November 22, 2010 Share Posted November 22, 2010 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. Link to comment Share on other sites More sharing options...
1123581321 Posted November 23, 2010 Author Share Posted November 23, 2010 How many string theories are there ? Link to comment Share on other sites More sharing options...
ajb Posted November 23, 2010 Share Posted November 23, 2010 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. Link to comment Share on other sites More sharing options...
johnmarsh Posted November 24, 2010 Share Posted November 24, 2010 i new for this forum but i understand ur question but i really not know whats meaning for this Link to comment Share on other sites More sharing options...
ajb Posted November 24, 2010 Share Posted November 24, 2010 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. Link to comment Share on other sites More sharing options...
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