We discuss geometry underlying orientifolds with non-trivial NS-NS B-flux. If D-branes wrap a torus with B-flux the rank of the gauge group is reduced due to non-commuting Wilson lines whose presence is implied by the B-flux. In the case of D-branes transverse to a torus with B-flux the rank reduction is due to a smaller number of D-branes required by tadpole cancellation conditions in the pres...

We consider non-perturbative six dimensional N = 1 space-time supersymmetric orientifolds of Type IIB on K3 with non-trivial NS-NS B-flux. All of these models are non-perturbative in both orientifold and heterotic pictures. Thus, some states in such compactifications arise in “twisted” open string sectors which lack world-sheet description in terms of D-branes. We also discuss their dual F-theo...

Abstract We show that under the assumption of existence canonical inner model with one Woodin cardinal $M_1$ , there is a $\mathsf {ZFC}$ in which $\mbox {NS}_{\omega _{1}}$ $\aleph _2$ -saturated and ${\Delta }_{1}$ -definable $\omega _1$ as parameter answers question S. D. Friedman L. Wu. also starting from an arbitrary universe cardinal, saturated ladder system $\vec {C}$ full Suslin tree T ...

ns c is LBNL’s Network Simulator [20]. The simulator is written in C++; it uses OTcl as a command and configuration interface. ns v2 has three substantial changes from ns v1: (1) the more complex objects in ns v1 have been decomposed into simpler components for greater flexibility and composability; (2) the configuration interface is now OTcl, an object oriented version of Tcl; and (3) the inte...

We give a construction for a general class of vertices in superstring field theory which include integration over bosonic moduli as well as the required picture changing insertions. We apply this procedure to find a covariant action for the NS-NS sector of Type II closed superstring field theory.

We consider six dimensional N = 1 space-time supersymmetric Type IIB orientifolds with non-zero untwisted NS-NS sector B-field. The B-field is quantized due to the requirement that the Type IIB spectrum be left-right symmetric. The presence of the B-field results in rank reduction of both 99 and 55 open string sector gauge groups. We point out that in some of the models with non-zero B-field th...