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High energy physics theory

Articles 1 - 17 of 17

Full-Text Articles in Physics

Dynamical Supersymmetry Breaking And The Linear Multiplet, P. Binétruy, M. K. Gaillard, T. R. Taylor Feb 2011

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 Feb 2011

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 Feb 2011

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 Feb 2011

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 Feb 2011

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 Feb 2011

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 Jan 2011

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 Jan 2011

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 Jan 2011

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 Jan 2011

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 Jan 2011

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 Jan 2011

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 ...


Asymptotic Infrared Fractal Structure Of The Propagator For A Charged Fermion, S. Gulzari, J. Swain, A. Widom Jan 2011

Asymptotic Infrared Fractal Structure Of The Propagator For A Charged Fermion, S. Gulzari, J. Swain, A. Widom

John Swain

It is well known that the long-range nature of the Coulomb interaction makes the definition of asymptotic "in" and "out" states of charged particles problematic in quantum field theory. In particular, the notion of a simple particle pole in the vacuum charged particle propagator is untenable and should be replaced by a more complicated branch cut structure describing an electron interacting with a possibly infinite number of soft photons. Previous work suggests a Dirac propagator raised to a fractional power dependent upon the fine structure constant, however the exponent has not been calculated in a unique gauge invariant manner. It ...


Can Hidden Gauginos Form Condensates?, Haim Goldberg Jan 2011

Can Hidden Gauginos Form Condensates?, Haim Goldberg

Haim Goldberg

Supersymmetry breaking may be linked to the formation of gaugino condensates in a hidden sector. In this work, the process of formation of the condensate is examined in a cosmological context, using an effective field theory of the gaugino bilinear which provides a reasonable interpolation between the high- and low-temperature phases. The implementation of anomaly requirements generates a large potential barrier between the zero-condensate configuration and that of the true (SUSY-breaking) vacuum. As a consequence, the transition to bubbles of true vacuum may be subject to an enormous exponential suppression. This leads to the same difficulties with inhomogeneity of the ...


Asymptotic Infrared Fractal Structure Of The Propagator For A Charged Fermion, S. Gulzari, J. Swain, A. Widom Jan 2011

Asymptotic Infrared Fractal Structure Of The Propagator For A Charged Fermion, S. Gulzari, J. Swain, A. Widom

Allan Widom

It is well known that the long-range nature of the Coulomb interaction makes the definition of asymptotic "in" and "out" states of charged particles problematic in quantum field theory. In particular, the notion of a simple particle pole in the vacuum charged particle propagator is untenable and should be replaced by a more complicated branch cut structure describing an electron interacting with a possibly infinite number of soft photons. Previous work suggests a Dirac propagator raised to a fractional power dependent upon the fine structure constant, however the exponent has not been calculated in a unique gauge invariant manner. It ...


Charged Lepton Oscillations And (G-2) Measurements, A. Widom, Y. N. Srivastava Jan 2011

Charged Lepton Oscillations And (G-2) Measurements, A. Widom, Y. N. Srivastava

Allan Widom

Traditional analysis of g = 2(1+κ) experiments for charged leptons use a classical spin vector picture. For muons, we here employ a more exact Dirac quantum four component spinor theory. Survival probabilities (including wave packet effects) are computed. These oscillate with the frequency Ω = (κeB/Mc) as has been assumed in previous muon (g −2) experimental analyses; i.e. muon survival probability oscillations are already at the root of previous succesful (g − 2) measurements. Further oscillations should also be observed if mixed neutrino mass matrices were to enter into the reactions (e.g. π+ → μ+ + νμ) producing muons.


Coupling The Supersymmetric 210 Vector Multiplet To Matter In So(10), Pran Nath, Raza M. Syed Jan 2011

Coupling The Supersymmetric 210 Vector Multiplet To Matter In So(10), Pran Nath, Raza M. Syed

Pran Nath

An analysis of the couplings of the 210 dimensional SO(10) vector multiplet to matter is given. Specifically we give an SU(5) × U(1) decomposition of the vector couplings 1̄6̄± − 16± − 210, where 16± is the semispinor of SO(10) chirality ±, using a recently derived basic theorem. The analysis is carried out using the Wess-Zumino gauge. However, we also consider the more general situation where all components of the vector multiplet enter in the couplings with the chiral fields. Here elimination of the auxiliary fields leads to a sigma model type nonlinear Lagrangian. Interactions of the type analysed ...