Subquark pregeometry with spontaneously broken conformal invariance

We present a model of subquark pregeometry in which the Higgs scalar as well as the space-time metric appears as a composite of subquark-antisubquark pairs. The effective langrangian becomes the einstein one with no cosmological term when conformal invariance is broken spontaneously.     

Low energy excitations in spin glasses

We discuss the nature of excitations that govern the low temperature thermodynamic behaviour of spin glasses and propose that the spin glass state is a space-time dependent ground state of a system of interacting spins wherein rotational invariance is broken spontaneously.     

About the realization of chiral symmetry in QCD2

Two dimensional massless quantum chromodynamics presents many features which resemble those of the true theory. In particular the spectrum consists of mesons and baryons arranged in flavour multiplets without parity doubling. We analyze the implications of chiral symmetry, which is not spontaneously broken in two dimensions, in the spectrum and in the quark condensate. We study how parity doubling, an awaited consequence of Coleman's theorem, is avoided due to the dimensionality of space-time and confinement. We prove that a chiral phase transition is not possible in the theory.     

Dynamical supersymmetry breaking in a finite field theoretical model

We present a supersymmetric field theory in two or three space-time dimensions with an internal symmetry of the O(N) type. In the large-N limit the model is finite and supersymmetry is spontaneously broken. The fields representing the order parameters of the broken supersymmetry phase acquire dynamics through quantum corrections. In particular the Goldstone fermion is a zero-mass fermionic bound state.     

Conformal invariance in quantum gravity

Trace anomalies in a conformal invariant theory do not arise when its conformal invariance in four dimensions is extended to an arbitrary number n of space-time dimensions: the theory can be made finite in any order of perturbation theory by conformal invariant counterterms in n dimensions. Such an extension of conformal invariance is possible provided one works in the framework of spontaneously broken conformal invariance. This is shown explicitly by working out several examples at the one-loop level and by examining the Ward identities which lead to a general proof.We speculate upon possible consequences of these results on the nature of gravitation and other fundamental interactions.     

Effective lagrangian for spontaneously broken N = 2 superconformal symmetry

In a general framework of non-linear realizations for space-time symmetries, we investigate the effective lagrangian for N = 2 superconformal symmetry which is spontaneously broken down to N = 2 super-Poincaré symmetry. For the case in which the dilation multiplet is a massless N = 2 gauge multiplet, we derive a low-energy effective lagrangian which describes the interaction of Nambu-Goldstone particles.     

A chiral SU(4) × SU(4) gauge theory of weak and electromagnetic interactions

A lepton hadron analogy is considered based on the gauge group SU(4)_L × SU(4)_R × U(1), which is broken entirely spontaneously. The model satisfies the physical requirements of the V-A theory, muon-electron universality, no neutral strangeness changing currents, the Cabibbo structure for the SU(3) currents, and triangle anomalies can be avoided. The contribution of the existing neutral currents to various neutrino processes are calculated.     

Topological Fermi liquids from Coulomb interactions in the doped honeycomb lattice

We propose a simple method for obtaining time reversal symmetry (T) broken phases in simple lattice models based on enlarging the unit cell. As an example we study the honeycomb lattice with nearest neighbor hopping and a local nearest neighbor Coulomb interaction V. We show that when the unit cell is enlarged to host six atoms that permits Kekulé distortions, self-consistent currents spontaneously form creating nontrivial magnetic configurations with total zero flux at high electron densities. A very rich phase diagram is obtained within a variational mean field approach that includes metallic phases with broken time reversal symmetry (T). The predominant (T) breaking configuration is an anomalous Hall phase, a realization of a topological Fermi liquid.     

Spontaneous breaking of electric-magnetic charge symmetry in local quantum field theory

It is shown that in local quantum field theory with electric and magnetic currents, duality transformations are always spontaneously broken. Possible implications are discussed leading to the screening of magnetic charge and the failure of the cluster property as in two-dimensional quantum electrodynamics.     

Mass matrix models: the sequel

The smallness of the quark sector parameters and the hierarchy between them could be the result of a horizontal symmetry broken by a small parameter. Such an explicitly broken symmetry can arise from an exact symmetry which is spontaneously broken. Constraints on the scales of new physics arise from new flavor-changing interactions and from Landau poles, but do not exclude the possibility of observable signatures at the TeV scale. Such a horizontal symmetry could also lead to many interesting results: (i) quark—squark alignment that would suppress, without squark degeneracy, flavor-changing neutral currents induced by supersymmetric particles, (ii) exact relations between mass ratios and mixing angles, (iii) a solution of the μ-problem and (iv) a natural mechanism for obtaining hierarchy among various symmetry-breaking scales.     

Degrees of symmetry in quantum field theories

A hierarchy of possible symmetries in quantum field theory is defined, which reaches from a purely mathematical invariance to the conventional physical invariance, including the commonly discussed type of spontaneously broken symmetry (SBS). It is shown that one type of SBS, which is usually not considered, naturally leads to theories with an algebra of non-conserved currents and a non-linearly transforming phenomenological Lagrangian. An exactly solvable model is given and some general remarks are made.     

Lorentz covariance and kinetic charge

There is a one-to-one correspondence between inequivalent covariant displaced Fock representations of the free relativistic field and the 1-cohomology of the Poincaré group with coefficients in the 1-particle space.Representations with positive energy are obtained from cocycles with finite energy which have particle-like properties and are interpreted as condensed states of matter without a sharply defined mass.The 1-cohomology groups ofP ₊ are calculated. These are trivial in 3- or 4-dimensional space-time, or if the mass is non-zero. Non-trivial cocycles for subgroups lead to representations in whichP-invariance is spontaneously broken. We recoverP-invariance in a direct integral representation possessing a gauge group, and a superselection structure labelled by the velocities of the condensed states of matter which are the cocycles determining each irreducible component of the representation. A model in 4-dimensional space-time is constructed.     

Local approach to dilatation invariance

Scale invariance is analyzed locally by coupling the energy-momentum tensor to a source which is the metric field of curved space-time. The resulting theory at the classical level has no mass parameters only if the general coordinate transformation group can be represented in Weyl's scheme. We further discuss the quantum extension of the theory; the Ward identities become anomalous under radiative corrections and the anomaly is shown to be connected with the instability of the classical metric field representation. The anomalies, recognized as the well-known trace anomalies for the energy-momentum tensor, are then reabsorbed by a perturbative alteration of the original metric field transformation law and we prove the modified Ward identities to be renormalizable in the flat limit. Finally we show that our approach is equivalent to the well-known parametric equations of the Callan-Symanzik type only if the dilatation invariance is not spontaneously broken. In the presence of spontaneous scale breaking we derive a functional equation which will be applied to cases of physical interest in a forthcoming paper.     

Gravitational Aharonov-Bohm Effect

We study a purely gravitational Aharonov-Bohm effect. The space-time curvature is concentrated in the quasiregular singularity of a cosmic string, outside of which space-time is (locally) flat. The symmetries of this field configuration are described by the groupoid symmetries rather than by the usual group symmetries. The groupoid in question is formed by homotopy classes of piecewise smooth paths in the cosmic string region. A gravitational counterpart of the Aharonov-Bohm effect occurs if the symmetry of the system, with respect to the groupoid action, is broken down.     

Dynamical supersymmetry breaking in two-dimensional N = 1 supergravity theories

We investigate a possible dynamical mechanism for spontaneous supersymmetrybreaking in N = 1 supergravity theories in 1 + 1 space-time dimensions. It will be shown that supersymmetry is never broken at the tree level, but it can be broken for a certain class of models by quantum effects due to trace anomalies of the energy-momentum tensor and the supercurrent.     

Spontaneously broken spacetime symmetries and Goldstone's theorem

Goldstone's theorem states that there is a massless mode for each broken symmetry generator. It has been known for a long time that the naive generalization of this counting fails to give the correct number of massless modes for spontaneously broken spacetime symmetries. We explain how to get the right count of massless modes in the general case, and discuss examples involving spontaneously broken Poincaré and conformal invariance.     

Anomaly constraints on supersymmetric effective lagrangians

In this paper we set constraints on the possible effective-lagrangian representations of supersymmetric gauge theories with spontaneously broken chiral flavor symmetries, by finding the conditions under which a Wess-Zumino term to represent the anomalous interactions can be constructed. We find that effective lagrangians for such theories are possible only for nonlinear sigma models defined on noncompact manifolds, and demonstrate the realization of this result in supersymmetric QCD. We also consider the Wess-Zumino term in the nonlinear realization of broken supersymmetry.     

Inflationary universe without GUTs

The existence of a primordial inflationary era is unavoidable due to the puzzling nature of semiclassical gravitation, regulated by Einstein's equations and the laws of quantum mechanics. This interaction appears to be controlled by a mass-dependent effective gravitational coupling constant. The latter undergoes an unexpected transition from a classical gravitational attractive to an antigravitational repulsive regime when the corresponding mass of a quantum matter field passes through a definite threshold. This induces in turn a gravitational, spontaneously broken symmetry phenomenon responsible for the presence of an unusual non-Minkowskian ground state: the inflationary de Sitter space-time. This then acquires the status of the primordial cosmological vacuum, the generic configuration of our cosmological history.     

Conserved currents and associated symmetries; Goldstone's theorem

We consider, in the framework of local field theory with translation symmetry, automorphisms connected with locally conserved currents. We show that such automorphisms lead to symmetries, i.e. are implementable by unitary operators, whenever the smallest mass in the theory is non-zero. Therefore we conclude that a spontaneously broken symmetry is possible only in the event that the smallest mass is zero. This establishes the theorem first conjectured byGoldstone.This work was supported by the National Science Foundation under contract NSF GP 2417.On leave of absence from University of Sao Paulo, Brazil.     

Tests of the space-time properties of neutral currents in electron-positron annihilation

Electron-positron processes are very valuable for investigating neutral currents. Interference between neutral currents and the electromagnetic current provides unambiguous tests of the space-time properties of neutral currents. We discuss the structure of this interference with particular reference to the process e⁺e^? → hadron + anything.