About the stability of the ground state of the bosonic string

In Polchinski's string theory vol 1, p. 23, it is said "It is a complicated question whether the bosonic string has any stable vacuum, and the answer is not known."

The book was published on 1998. What is the current answer of this question? Is bosonic string a realistic theory nowadays?

In addition, the ground state here is $$|0;k \rangle$$, not $$| \mathrm{vacuum} \rangle$$. Is that because the latter one is absolute nothing so we don't study?

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Thanks a lot. Would you provide a reference about no tachions in 26 dimensional bosonic string theory? Polchinski's book seems say there is tachyon :( – user26143 Jul 14 '13 at 16:48
@Dilaton The 26D 'vacuum' has tachyonic excitations. It isn't stable. – user1504 Jul 14 '13 at 16:57
The answer is still not known. – user1504 Jul 14 '13 at 16:59
@BebopButUnsteady: Bosonic ST isn't research levelp, shalll I remove the tag? – centralcharge Aug 2 '13 at 12:59