Claudio A. Scrucca

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We study anomalous Wess-Zumino couplings of D-branes and O-planes in a general background and derive them from a direct string computation by fac-torizing in the RR channel various one-loop amplitues. In particular, we find that Op-planes present gravitational anomalous couplings involving the Hirze-bruch polynomiaî L, similarly to the roof genusˆA encoding(More)
We perform a general study about the existence of non-supersymmetric minima with vanishing cosmological constant in supergravity models involving only chiral superfields. We study the conditions under which the matrix of second derivatives of the scalar potential is positive definite, and show that there exist very simple and strong necessary conditions for(More)
We further develop on the study of the conditions for the existence of locally stable non-supersymmetric vacua with vanishing cosmological constant in supergravity models involving only chiral superfields. Starting from the two necessary conditions for flatness and stability derived in a previous paper (which involve the Kähler metric and its Riemann tensor(More)
We use the boundary state formalism to study the interaction of two moving identical D-branes in the Type II superstring theory compactified on orb-ifolds. By computing the velocity dependence of the amplitude in the limit of large separation we can identify the nature of the different forces between the branes. In particular, in the Z 3 orbifold case we(More)
We study higher-dimensional non-supersymmetric orbifold models where the Higgs field is identified with some internal component of a gauge field. We address two important and related issues that constitute severe obstacles towards model building within this type of constructions: the possibilities of achieving satisfactory Yukawa couplings and Higgs(More)
We give an overview of the issue of anomalies in field theories with extra dimensions. We start by reviewing in a pedagogical way the computation of the standard perturbative gauge and gravitational anomalies on non-compact spaces, using Fujikawa's approach and functional integral methods, and discuss the available mechanisms for their cancellation. We then(More)
We study spin interactions between two moving D-branes using the Green-Schwarz formalism of boundary states. We focus our attention on the leading terms for small velocities v, of the form v 4−n /r 7−p+n (v 2−n /r 3−p+n) for p-p (p-p+4) systems, with 16 (8) supercharges. In analogy with the standard G-S computation of massless four-point one-loop amplitudes(More)
We discuss various D-brane configurations in 4-dimensional orbifold compactifications of type II superstring theory which are point-like 0-branes from the 4-dimensional space-time point of view. We analyze their interactions and compute the amplitude for the emission of a massless NSNS boson from them, in the case where the branes have a non vanishing(More)