arXiv subjects
Publications and source records attributed to Ghadir Jafari.
Gravitational couplings in bulk space-time include those terms which are fixed by scattering amplitude of strings and ambiguous terms that are coming from the field redefinitions. These field redefinitions can be fixed in the bulk by ghost-free condition. In this paper we have revised the effective gravitational couplings on D-branes by including the field redefinitions. We find the gravitational effective action up to $α'^2$-order.
Recently, it has been observed that in a T-duality invariant world-volume theory in flat spacetime, all orders of gauge field strength and all orders of the D-brane velocity appear in two specific matrices. Using these two matrices, we construct the world-volume couplings of two massless NSNS states at order $α'^2$ and all orders of the velocity and the gauge field strength, by requiring them to be invariant under the linear T-duality. The standard extension $F\rightarrow F+P[B]$, then produces all orders of the pull-back of B-field into the action. We compare the resulting couplings for zero velocity and gauge field strength, with the $α'^2$ terms of the disk-level S-matrix element of two massless NSNS vertex operators in the presence of a constant background B-field. We have found an exact agreement.
In bosonic string theory, it is known that the Buscher rules for the T-duality transformations receive quantum corrections at order $α'$. In this paper, we use the consistency of the gravity couplings on the D-brane effective action at order $α'$, with the above T-duality transformations to find the B-field and the dilaton couplings. We show that these couplings are fully consistent with the corresponding disk-level S-matrix elements in string theory.