Open Access. Powered by Scholars. Published by Universities.^{®}

- File Type

Articles **1** - **12** of ** 12**

## Full-Text Articles in Physics

Dynamical Supersymmetry Breaking And The Linear Multiplet, P. Binétruy, M. K. Gaillard, T. R. Taylor

#### Dynamical Supersymmetry Breaking And The Linear Multiplet, P. Binétruy, M. K. Gaillard, T. R. Taylor

*Tomasz Taylor*

We analyze gaugino condensation in the presence of a dilaton and an antisymmetric tensor field, with couplings reminiscent of string theories. The degrees of freedom relevant to a supersymmetric description of the effective theory below the scale of condensation are discussed in this context.

Duality Of N = 2 Heterotic-Type I Compactifications In Four Dimensions, I. Antoniadis, H. Partouche, T. R. Taylor

#### Duality Of N = 2 Heterotic-Type I Compactifications In Four Dimensions, I. Antoniadis, H. Partouche, T. R. Taylor

*Tomasz Taylor*

We discuss type I -- heterotic duality in four-dimensional models obtained as a Coulomb phase of the six-dimensional U(16) orientifold model compactified on T^2 with arbitrary SU(16) Wilson lines. We show that Kahler potentials, gauge threshold corrections and the infinite tower of higher derivative F-terms agree in the limit that corresponds to weak coupling, large T^2 heterotic compactifications. On the type I side, all these quantities are completely determined by the spectrum of N=2 BPS states that originate from D=6 massless superstring modes.

Duality In Superstring Compactifications With Magnetic Field Backgrounds, I. Antoniadis, E. Gava, K. S. Narain, T. R. Taylor

#### Duality In Superstring Compactifications With Magnetic Field Backgrounds, I. Antoniadis, E. Gava, K. S. Narain, T. R. Taylor

*Tomasz Taylor*

Motivated by the work of Polchinski and Strominger on type IIA theory, where the effect of non-trivial field strengths for p-form potentials on a Calabi-Yau space was discussed, we study four-dimensional heterotic string theory in the presence of magnetic field on a 2-cycle in the internal manifold, for both N=4 and N=2 cases. We show that at special points in the moduli space, certain perturbative charged states become tachyonic and stabilize the vacuum by acquiring vacuum expectation values, thereby restoring supersymmetry. We discuss both the cases where the tachyons appear with a tower of Landau levels, which become ...

Duality Symmetries In N = 2 Heterotic Superstring, I. Antoniadis, S. Ferrara, E. Gava, K. Narain, T. Taylor

#### Duality Symmetries In N = 2 Heterotic Superstring, I. Antoniadis, S. Ferrara, E. Gava, K. Narain, T. Taylor

*Tomasz Taylor*

We review the derivation and the basic properties of the perturbative prepotential in N=2 compactifications of the heterotic superstring. We discuss the structure of the perturbative monodromy group and the embedding of rigidly supersymmetric monodromies associated with enhanced gauge groups, at both perturbative and non-perturbative level.

Dual N = 2 Susy Breaking, I. Antoniadis, T. Taylor

#### Dual N = 2 Susy Breaking, I. Antoniadis, T. Taylor

*Tomasz Taylor*

We discuss spontaneous supersymmetry breaking in $N=2$ globally supersymmetric theories describing abelian vector multiplets. The most general form of the action admits, in addition to the usual Fayet-Iliopoulos term, a magnetic Fayet-Iliopoulos term for the auxiliary components of dual vector multiplets. In a generic case, this leads to a spontaneous breakdown of one of the two supersymmetries. In some cases however, dyon condensation restores $N=2$ SUSY vacuum. This talk is based on the work done in collaboration with H. Partouche \cite{apt}.

Effective Μ-Term In Superstring Theory, I. Antoniadis, E. Gava, K. Narain, T. Taylor

#### Effective Μ-Term In Superstring Theory, I. Antoniadis, E. Gava, K. Narain, T. Taylor

*Tomasz Taylor*

In four-dimensional compactifications of the heterotic superstring theory the K\"ahler potential has a form which generically induces a superpotential mass term for Higgs particles once supersymmetry is broken at low energies. This ``$\mu$-term'' is analyzed in a model-independent way at the tree level and in the one-loop approximation, and explicit expressions are obtained for orbifold compactifications. Additional contributions which arise in the case of supersymmetry breaking induced by gaugino condensation are also discussed.

Aspects Of Type I– Type Ii– Heterotic Triality In Four Dimensions, I. Antoniadis, C. Bachas, C. Fabre, H. Partouche, T. R. Taylor

#### Aspects Of Type I– Type Ii– Heterotic Triality In Four Dimensions, I. Antoniadis, C. Bachas, C. Fabre, H. Partouche, T. R. Taylor

*Tomasz Taylor*

We discuss the equivalence between Type I, Type II and Heterotic N = 2 superstring theories in four dimensions. We study the effective field theory of Type I models obtained by orientifold reductions of Type IIB compactifications on K₃ × T². We show that the perturbative prepotential is determined by the one-loop corrections to the Planck mass and is associated to an index. As is the case for threshold corrections to gauge couplings, this renormalization is entirely due to N = 2 BPS states that originate from D = 6 massless string modes. We apply our result to the so-called S-T-U model which admits ...

Complete Six-Gluon Disk Amplitude In Superstring Theory, Stephan Stieberger, Tomasz R. Taylor

#### Complete Six-Gluon Disk Amplitude In Superstring Theory, Stephan Stieberger, Tomasz R. Taylor

*Tomasz Taylor*

We evaluate all next-to-maximal helicity violating (NMHV) six-gluon amplitudes in type I open superstring theory in four dimensions, at the disk level, to all orders in α′. Although the computation utilizes supersymmetric Ward identities, the result holds for all compactifications, even for those that break supersymmetry and is completely model-independent. Together with the maximally helicity violating (MHV) amplitudes presented in the previous work, our results provide the complete six-gluon disk amplitude.

Amplitude For N-Gluon Superstring Scattering, Stephan Stieberger, Tomasz R. Taylor

#### Amplitude For N-Gluon Superstring Scattering, Stephan Stieberger, Tomasz R. Taylor

*Tomasz Taylor*

We consider scattering processes involving N gluonic massless states of open superstrings with certain Regge slope α′. At the semi-classical level, the string world-sheet sweeps a disk and N gluons are created or annihilated at the boundary. We present exact expressions for the corresponding amplitudes, valid to all orders in α′, for the so-called maximally helicity violating configurations, with N=4, 5 and N=6. We also obtain the leading O(α′²) string corrections to the zero-slope N-gluon Yang-Mills amplitudes.

Branes And Fluxes In D=5 Calabi–Yau Compactifications Of M-Theory, Michał Spaliński, Tomasz R. Taylor

#### Branes And Fluxes In D=5 Calabi–Yau Compactifications Of M-Theory, Michał Spaliński, Tomasz R. Taylor

*Tomasz Taylor*

We discuss Poincaré three-brane solutions in D = 5 M-Theory compactifications on Calabi-Yau (CY) threefolds with G-fluxes. We show that the vector moduli freeze at an attractor point. In the case with background flux only, the spacetime geometry contains a zero volume singularity with the three-brane and the CY space shrinking simultaneously to a point. This problem can be avoided by including explicit three-brane sources. We consider two cases in detail: a single brane and, when the transverse dimension is compactified on a circle, a pair of branes with opposite tensions.

Axion Couplings And Effective Cut-Offs In Superstring Compactifications, Mary K. Gaillard, T. R. Taylor

#### Axion Couplings And Effective Cut-Offs In Superstring Compactifications, Mary K. Gaillard, T. R. Taylor

*Tomasz Taylor*

We use the linear supermultiplet formalism of supergravity to study axion couplings and chiral anomalies in the context of field-theoretical Lagrangians describing orbifold compactifications beyond the classical approximation. By matching amplitudes computed in the effective low energy theory with the results of string loop calculations we determine the appropriate counterterm in this effective theory that assures modular invariance to all loop order. We use supersymmetry consistency constraints to identify the correct ultra-violet cutoffs for the effective low energy theory. Our results have a simple interpretation in terms of two-loop unification of gauge coupling constants at the string scale.

Calculable E−1/Λ Effects, I. Antoniadis, B. Pioline, T. R. Taylor

#### Calculable E−1/Λ Effects, I. Antoniadis, B. Pioline, T. R. Taylor

*Tomasz Taylor*

We identify and evaluate a class of physical amplitudes in four-dimensional N = 4 superstring theory, which receive, in the weak coupling limit, contributions of order e−1/λ, where λ is the type II superstring coupling constant. They correspond to four-derivative Ƒ˜1 interaction terms involving the universal type II dilaton supermultiplet. The exact result, obtained by means of a one-loop computation in the dual heterotic theory compactified on T⁶, is compared with the perturbation theory on the type II side, and the e−1/λ contributions are associated to non-perturbative effects of Euclidean solitons (D-branes) wrapped on K3 × T2 ...