Why is Type 0 string theory not so popular?

Question

Of course Type 0 string theory contans tachyons in its spectrum that male it unstable. Why is there not some equivalent to GSO projection to get rid of those states? Also are there any non-perturbative dualities for this string theory? Finally, and what I care most, what do we learn from type 0 string theory that we can use in other theories?

Answer 1

A GSO Projection does remove the fermions from the Type 0 string theories. In fact the two theories (0A, 0B) are exactly differentiated by their chirality, which is decided by the GSO projection.

However, the Type 0 string does not have spacetime supersymmetry (only worldsheet supersymmetry), and doesn't contain fermions in its spectrum.

As for dualities, there is a T-duality between the 0A and 0B strings, [1] (.ps.gz file, direct download), [2] (.pdf file, direct download) [3], [4].

Answering your last question, there is some interest in two-dimensional type 0 strings, and it's also used as a toy model to study closed string tachyon condensation among other properties.

Comments

Is there some paper which exposes what you say? Additionaly, is it not a good feature for phenomenology to not have target space supersymmetry?

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@JohnK Well, it can be found in any standard string theory textbook that covers Type 0 strings (BBS does not, I think Polchinski does).

It's not a "feature" for a string theory to not have spacetime supersymmetry - what makes you think it is?