Abstract

We show that the triviality of the entire cohomology of the new BRST operator Q around the tachyon vacuum is equivalent to the Q-exactness of the identity I of the star-algebra. We use level truncation to show that as the level is increased, the identity becomes more accurately Q-exact. We carry our computations up to level nine, where an accuracy of 3% is attained. Our work supports, under a new light, Sen's conjecture concerning the absence of open string degrees of freedom around the tachyon vacuum. As a by-product, a new and simple expression for I in terms of Virasoro operators is found.

Publication Type:	Article
Additional Information:	The original publication is available at http://iopscience.iop.org/1126-6708/2001/07/016/ archiveprefix: arXiv primaryclass: hep-th
Publisher Keywords:	Bosonic strings, BRST symmetry, gauge symmetry
Subjects:	Q Science > QC Physics
Departments:	School of Science & Technology > Mathematics

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