Just as D-brane charge of Type IIA and Type IIB superstrings is classified, respectively, by K(X) and K(X), Ramond-Ramond fields in these theories are classified, respectively, by K(X) and K(X). By analyzing a recent proposal for how to interpret quantum self-duality of RR fields, we show that the Dirac quantization formula for the RR p-forms, when properly formulated, receives corrections that...

We describe the geometry of type II string compactifications to 6– and 7–dimensional backgrounds with Ramond–Ramond–fields in terms of principal fibre bundle as generalised SU(3)– and G2– structures. We endow these structures with an integrability condition which can be characterised as a constrained critical point for the generalised Hitchin functional and provides a solution to the supersymme...

These lectures provide an introduction to perturbative string theory and its construction on spaces with background Ramond flux. Traditional covariant quantization of the string and its connection with vertex operators and conformal invariance of the worldsheet theory are reviewed. A supersymmetric covariant quantization of the superstring in six and ten spacetime dimensions is discussed. Corre...

We give a detailed discussion of the disk amplitudes with one closed string insertion, which we used to construct the supergravity couplings of noncommutative D-branes to the RR potentials, given in hep-th/0104139. We prove the inclusion of Elliott’s formula, the integer-valued modification of the noncommutative Chern character, to all orders in the gauge field. We also give a detailed comparis...

We study how non-BPS type II D-branes couple to R-R potentials. Upon tachyon condensation the couplings we find give rise to the Wess-Zumino action of BPS D-branes. In a seminal series of papers, Sen has shown how to obtain an exact conformal field theory description of non-BPS D-branes (see [1] for two of the main papers and two recent reviews). In this setup, a non-BPS D(p − 1)-brane remains ...

We glue together two branched spheres by sewing of two Ramond (dual) two-fermion string vertices and present a rigorous analytic derivation of the closed expression for the four-fermion string vertex. This method treats all oscillator levels collectively and the obtained answer verifies that the closed form of the four vertex previously argued for on the basis of explicit results restricted to ...

nitrogen acquisition of Chrysanthemum morifolium under salt stress 2 3 Yanhong Wang1*, Minqiang Wang1, Yan Li1, Aiping Wu2, Juying Huang3 4 5 1 State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University , Hangzhou 311300, 6 Zhejiang, China; [email protected] 7 2 Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, Hunan 8 Agricultural University, Chang...

In the Green-Schwarz formalism, the closed string worldsheet of the IIB theory couples to Ramond-Ramond (RR) fluxes through spinor bilinears. We study the effect of such fluxes by analyzing the supersymmetry transformation of the worldsheet in general backgrounds. We show that, in the presence RR fields, the closed string can get ‘polarized’, as the spinors acquire non-zero vevs in directions c...

We find a new stable rotator solution in D0-brane matrix mechanics. The solution is interpreted as a D2/D0 brane bound state, constructed as a transversely rotating ellipsoidal membrane with N D0-branes pinned over it. From the membrane point of view the attractive force of tension is exactly cancelled by the repulsive centrifugal force. Dynamical properties of the system are investigated, in p...

In order to study vertex operators for the Type IIB superstring on AdS space, we derive supersymmetric constraint equations for the vertex operators in AdS3 × S backgrounds with Ramond-Ramond flux, using Berkovits-Vafa-Witten variables. These constraints are solved to compute the vertex operators and show that they satisfy the linearized D = 6, N = (2, 0) equations of motion for a supergravity ...