D-branes, orbifolds, and Ext groups

Sheldon Katz, Tony Pantev, Eric Sharpe

Research output: Contribution to journalArticlepeer-review


In this note we extend previous work on massless Ramond spectra of open strings connecting D-branes wrapped on complex manifolds, to consider D-branes wrapped on smooth complex orbifolds. Using standard methods, we calculate the massless boundary Ramond sector spectra directly in BCFT, and find that the states in the spectrum are counted by Ext groups on quotient stacks (which provide a notion of homological algebra relevant for orbifolds). Subtleties that cropped up in our previous work also appear here. We also use the McKay correspondence to relate Ext groups on quotient stacks to Ext groups on (large radius) resolutions of the quotients. As stacks are not commonly used in the physics community, we include pedagogical discussions of some basic relevant properties of stacks.

Original languageEnglish (US)
Pages (from-to)263-300
Number of pages38
JournalNuclear Physics B
Issue number1-2
StatePublished - Nov 24 2003

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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