Infinity cancellations in SO(32) superstring theory

Type I superstring theory was previously shown to be anomaly-free if the gauge group is SO(32). Here it is demonstrated that the same group is also singled out by the requirement that infinities can be canceled by combining diagrams.     

Relation between anomaly in type-I superstring and anomaly in its effective theory

We explicitly calculate the hexagon and heptagon (covariant) gauge anomaly including the precise numerical coefficients in type-I open superstring. The calculation is performed by using the Pauli-Villars regularization on the basis of the stringy Ward identity, which is an assumption weaker than the cancelled propagator argument. We show that the anomalies in the effective theory are realized as the zero slope limit (α^′→0) of the string anomalies in a very non-trivial way in the present calculational scheme. This non-trivial realization in higher point (n≧8) anomalies is also discussed.     

Phenomenology of superstring theories with SO(10) unification

The phenomenology of superstring theories in which the gauge symmetry after compactification is SO(10) × E′₈, instead of E₆ × E′₈, is discussed. In particular, the generation of an intermediate scale, the radiative breaking of electroweak symmetry, and the supersymmetric particle spectrum are investigated.     

Equivalence of two-loop superstring amplitudes in the pure spinor and Ramond-Neveu-Schwarz formalisms

The pure spinor formalism for the superstring has recently been used to compute massless four-point two-loop amplitudes in a manifestly super-Poincaré covariant manner. In this Letter, we show that when all four external states are Neveu-Schwarz states, the two-loop amplitude coincides with the Ramond-Neveu-Schwarz result.     

Cancellation of leading divergences in multiloop closed superstring amplitudes

We discuss the general problem of divergences and the particularly important “tadpole” configuration for multiloop amplitudes in the closed superstring - or heterotic string - covariant theory, with any number of external legs. We show that, due to a factor coming from the supermoduli, the tachyon divergence in the tadpole is cancelled in each spin structure contribution separately.     

SO(4) theory of antiferromagnetism and superconductivity in Bechgaard salts

Motivated by recent experiments with Bechgaard salts, we investigate the competition between antiferromagnetism and triplet superconductivity in quasi-one-dimensional electron systems. We unify the two orders in an SO(4) symmetric framework, demonstrating the existence of such symmetry in one-dimensional Luttinger liquids. SO(4) symmetry strongly constrains the phase diagram, leading to coexistence regions of antiferromagnetic, superconducting, and normal phases, as observed in (TMTSF)(2)PF(6). We predict a sharp neutron scattering resonance in superconducting samples.     

Graded constraint algebras,OSP(1, 1|2) and superstring theory

Earlier, we have established that, for a constrained system with a first class bosonic constraint algebra, the standard BRST invariance generalizes to an OSP(1, 1|2) symmetry, with four nilpotent and anticommuting BRST-type operators. Here we generalize this to arbitrary constrained systems with a graded first class constraint algebra. Our approach is based on the Fradkin- Vilkovisky formalism and uses a relation between abelian and nonabelian constraint algebras. Subsidiary constraints and generalized structure constants play an important role in the construction. As an application, we construct the OSP(1, 1|2) generators for superstrings. Here the subsidiary constraints are identified with physically relevant operators used in the unitarity proof.     

An SO(10) supersymmetric grand unified theory

A realistic supersymmetric SO(10) grand unified theory is explicitly constructed. The neutrino masses turn out to be 10^?5 eV or less. It is also found that the proton life time can be longer than 10³¹ yr.     

Fixed twist dynamics of SO(3) gauge theory

We perform a thorough study of 3+1-dimensional SO(3) LGT for fixed-twist background. We concentrate in particular on the physically significant trivial and 1-twist sectors. Introducing a ℤ₂ monopole chemical potential the 1st order bulk transition is moved down in the strong coupling region and weakened to 2nd order in the 4-dimensional Ising model universality class. In this extended phase diagram we gain access to a confined phase in every fixed-twist sector of the theory. The Pisa disorder operator is employed together with the Polyakov loop to study the confinement–deconfinement transition in each sector. Due to the specific properties of both operators, most results can be used to gain insight in the ergodic theory, where all twist sectors should be summed upon. An explicit mapping of each fixed-twist theory to effective positive plaquette models with fixed-twisted boundary conditions is applied to better establish their properties in the different phases.     

Picture changing operation and BRST-cohomology in superstring field theory

It is shown that the BRST-cohomology in the enlarged bosonized formulation of the superstring field theory is trivial, and the “homotopy operation” that implements this traviality is given. As a result of truncating the enlarged representation to the irreducible one, the picture changing operation emerges in a quite natural way as a residual effect of the underlying structure.     

Gravitational scattering of massless scalars in QFT and superstring theory

In this paper we perform the calculation of the gravitational scattering amplitude for 4 massless scalars in quantum field theory and Type II superstring theory. We show that the results agree, providing an example of how gravity is incorporated in the superstring theory. During the calculation we quantize gravitational action to derive graviton propagator and interaction vertex with massless scalar. We also calculate general 3‐point and 4‐point scattering amplitudes in SST for open and closed massless strings in NS sector.     

Potentials of pointlike particles in gauge theory with a dilaton

I examine the potential of a pointlike particle carrying SU (N _c) charge in a gauge theory with a dilaton. The potential depends on boundary conditions imposed on the dilaton: For a dilaton that vanishes at infinity the resulting potential is a regulatized Coulomb potential of the form (r+r _ϕ)⁻¹, withr _ϕ, inversely proportional to the decay constant of the dilaton. Another natural constraint on the dialaton ϕ is independence of (1/g ²) exp(ϕ/f_ϕ) from the gauge couplingg. This requirement yields a confining potential proportional tor.