Search results for "D-branes"
showing 2 items of 2 documents
Q7-branes and their coupling to IIB supergravity
2007
We show how, by making use of a new basis of the IIB supergravity axion-dilaton coset, SL(2,R)/SO(2), 7-branes that belong to different conjugacy classes of the duality group SL(2,R) naturally couple to IIB supergravity with appropriate source terms characterized by an SL(2,R) charge matrix Q. The conjugacy classes are determined by the value of the determinant of Q. The (p,q) 7-branes are the branes in the conjugacy class detQ = 0. The 7-branes in the conjugacy class detQ > 0 are labelled by three numbers (p,q,r) which parameterize the matrix Q and will be called Q7-branes. We construct the full bosonic Wess--Zumino term for the Q7-branes. In order to realize a gauge invariant coupling …
Oh, wait, O8 de Sitter may be unstable!
2021
We analyze the stability of four-dimensional de Sitter vacua constructed by compactifying massive Type IIA supergravity in the presence of two O8 sources [1]. When embedded in String Theory the first source has a clear interpretation as an O8$_-$ plane, but the second one could correspond to either an O8$_+$ plane or to an O8$_-$ plane with 16 D8-branes on top. We find that this latter solution has a tachyonic instability, corresponding to the D8-branes moving away from the O8$_-$ plane. We comment on the possible ways of distinguishing between these sources.