Orientifolds and Twisted KR Theory


Distler, J. (2008). Orientifolds and Twisted KR Theory. Perimeter Institute. https://pirsa.org/08090003


Distler, Jacques. Orientifolds and Twisted KR Theory. Perimeter Institute, Sep. 09, 2008, https://pirsa.org/08090003


          @misc{ pirsa_08090003,
            doi = {},
            url = {https://pirsa.org/08090003},
            author = {Distler, Jacques},
            keywords = {Quantum Fields and Strings},
            language = {en},
            title = {Orientifolds and Twisted KR Theory},
            publisher = {Perimeter Institute},
            year = {2008},
            month = {sep},
            note = {PIRSA:08090003 see, \url{https://pirsa.org}}


I will report on some work in progress with Dan Freed and Greg Moore. In an orientifold background, D-brane charge takes values in a certain twisted version of KR Theory. Moreover, there is a nontrivial background charge (\'tadpole\'). Up \'til now, this background charge has only been calculated rationally -- i.e., ignoring torsion. We derive a formula for it, over the integers. Only after \'inverting 2\', does the charge localize to the fixed point sets of the orientifold action, and we can give a compact formula for it. This reproduces the previously known rational results, but contains new information.