TY - JOUR
T1 - D-branes, B fields, and Ext groups
AU - Cǎldǎraru, Andrei
AU - Katz, Sheldon
AU - Sharpe, Eric
PY - 2003/5
Y1 - 2003/5
N2 - In this paper we extend previous work on calculating massless boundary Ramond sector spectra of open strings to include cases with nonzero flat B fields. In such cases, D-branes are no longer well-modeled precisely by sheaves, but rather they are replaced by 'twisted' sheaves, reflecting the fact that gauge transformations of the B field act as affine translations of the Chan-Paton factors. As in previous work, we find that the massless boundary Ramond sector states are counted by Ext groups - this time, Ext groups of twisted sheaves. As before, the computation of BRST cohomology relies on physically realizing some spectral sequences. Subtleties that cropped up in previous work also appear here.
AB - In this paper we extend previous work on calculating massless boundary Ramond sector spectra of open strings to include cases with nonzero flat B fields. In such cases, D-branes are no longer well-modeled precisely by sheaves, but rather they are replaced by 'twisted' sheaves, reflecting the fact that gauge transformations of the B field act as affine translations of the Chan-Paton factors. As in previous work, we find that the massless boundary Ramond sector states are counted by Ext groups - this time, Ext groups of twisted sheaves. As before, the computation of BRST cohomology relies on physically realizing some spectral sequences. Subtleties that cropped up in previous work also appear here.
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U2 - 10.4310/atmp.2003.v7.n3.a1
DO - 10.4310/atmp.2003.v7.n3.a1
M3 - Article
AN - SCOPUS:29444433358
SN - 1095-0761
VL - 7
SP - 381
EP - 405
JO - Advances in Theoretical and Mathematical Physics
JF - Advances in Theoretical and Mathematical Physics
IS - 3
ER -