Showing papers in "Physical Review D in 1980"
TL;DR: In this article, the neutrinos belonging to isodoublets and neutrino isosinglets should decay into three lighter ones, which has the same effect as the neutral currents.
Abstract: We analyze SU(2)\ifmmode\times\else\texttimes\fi{}U(1) theories, denoted by ($n, m$), in which there are $n$ neutrinos belonging to isodoublets and $m$ neutrino isosinglets. The charged-current weak interactions are described by a rectangular matrix $K$ which we explicitly parametrize. The neutral-current neutrino interactions are described by a square matrix $P={K}^{+}K$. This has the consequences that neutrinos may decay into three lighter ones and that neutrino oscillations involving neutral-current interactions should exist. The general formalism for the latter situation is given. Associated material on parametrization of unitary matrices and the quantum theory of Majorana particles is also briefly discussed.
2,929 citations
TL;DR: In this article, a systematic analysis in perturbative quantum chromodynamics (QCD) of large-momentum-transfer exclusive processes is presented, where the scaling behavior, angular dependence, helicity structure, and normalization of elastic and inelastic form factors and large-angle exclusive scattering amplitudes for hadrons and photons are given.
Abstract: We present a systematic analysis in perturbative quantum chromodynamics (QCD) of large-momentum-transfer exclusive processes. Predictions are given for the scaling behavior, angular dependence, helicity structure, and normalization of elastic and inelastic form factors and large-angle exclusive scattering amplitudes for hadrons and photons. We prove that these reactions are dominated by quark and gluon subprocesses at short distances, and thus that the dimensional-counting rules for the power-law falloff of these amplitudes with momentum transfer are rigorous predictions of QCD, modulo calculable logarithmic corrections from the behavior of the hadronic wave functions at short distances. These anomalous-dimension corrections are determined by evolution equations for process-independent meson and baryon "distribution amplitudes" $\ensuremath{\varphi}({x}_{i}, Q)$ which control the valence-quark distributions in high-momentum-transfer exclusive reactions. The analysis can be carried out systematically in powers of ${\ensuremath{\alpha}}_{s}({Q}^{2})$, the QCD running coupling constant. Although the calculations are most conveniently carried out using light-cone perturbation theory and the light-cone gauge, we also present a gauge-independent analysis and relate the distribution amplitude to a gauge-invariant Bethe-Salpeter amplitude.
2,239 citations
TL;DR: The physical interpretation of perturbations of homogeneous, isotropic cosmological models in the early Universe, when the perturbation is larger than the particle horizon, is clarified by defining a complete set of gauge-invariant variables as discussed by the authors.
Abstract: The physical interpretation of perturbations of homogeneous, isotropic cosmological models in the early Universe, when the perturbation is larger than the particle horizon, is clarified by defining a complete set of gauge-invariant variables. The linearized perturbation equations written in these variables are simpler than the usual versions, and easily accommodate an arbitrary background equation of state, entropy perturbations, and anisotropic pressure perturbations. Particular attention is paid to how a scalar (density) perturbation might be generated by stress perturbations at very early times, when the non-gauge-invariant perturbation in the density itself is ill-defined. The amplitude of the fractional energy density perturbation at the particle horizon cannot be larger, in order of magnitude, than the maximum ratio of the stress perturbation to the background energy density at any earlier time, unless the perturbation is inherent in the initial singularity.
2,114 citations
TL;DR: In this article, the decay of the ground state of higher energy is modeled as a false vacuum, rendered unstable by barrier penetration, and the effect of gravitation on the decay process is considered.
Abstract: It is possible for a classical field theory to have two stable homogeneous ground states, only one of which is an absolute energy minimum. In the quantum version of the theory, the ground state of higher energy is a false vacuum, rendered unstable by barrier penetration. There exists a well-established semiclassical theory of the decay of such false vacuums. In this paper, we extend this theory to include the effects of gravitation. Contrary to naive expectation, these are not always negligible, and may sometimes be of critical importance, especially in the late stages of the decay process.
1,467 citations
TL;DR: In this article, a systematic investigation of all simple possibilities of having massive neutrinos in SU(2) models of electroweak interactions, without the ad hoc imposition of lepton number conservation, is presented.
Abstract: We make a systematic investigation of all simple possibilities of having massive neutrinos in SU(2)\ifmmode\times\else\texttimes\fi{}U(1) models of electroweak interactions, without the ad hoc imposition of lepton-number conservation. The minimal standard model is enlarged with triplet or singly or doubly charged singlet scalars as well as fermions in singlet and doublet representations. We find that in all cases the neutrino mass eigenstates are Majorana fields. This is so even though right-handed neutrino fields are added to the model. When mass terms of the Dirac type are also present (and if ${\ensuremath{
u}}_{R}'\mathrm{s}$ also have small masses) neutrinos will oscillate into antineutrinos (which, we argue, are most likely "sterile"). General fermion mass terms of both Dirac and Majorana types are studied and the results are included in the Appendix.
920 citations
TL;DR: In this article, the large-$N$ limit of the two-dimensional Wilson lattice gauge theory is explicitly evaluated for all fixed ε = 2 by steepest-descent methods.
Abstract: The large-$N$ limit of the two-dimensional $\mathrm{U}(N)$ (Wilson) lattice gauge theory is explicitly evaluated for all fixed $\ensuremath{\lambda}={g}^{2}N$ by steepest-descent methods. The $\ensuremath{\lambda}$ dependence is discussed and a third-order phase transition, at $\ensuremath{\lambda}=2$, is discovered. The possible existence of such a weak- to strong-coupling third-order phase transition in the large-$N$ four-dimensional lattice gauge theory is suggested, and its meaning and implications are discussed.
897 citations
TL;DR: In this paper, the authors compared the results of the naive model with the data on the π-psi family and showed that the latter model does not give acceptable values of the absolute leptonic widths, which is attributed to large quantum-chromodynamic corrections to the van Royen-Weisskopf formula.
Abstract: The charmonium model, formulated in detail in an earlier publication, is compared in a comprehensive fashion with the data on the $\ensuremath{\psi}$ family. The parameters of the "naive" model, in which the system is described as a $c\overline{c}$ pair, are determined from the observed positions of $\ensuremath{\psi}$, ${\ensuremath{\psi}}^{\ensuremath{'}}$, and the $P$ states. The model then yields a successful description of the spectrum of spin-triplet states above the charm threshold. It also accounts for the ratio of the leptonic widths of ${\ensuremath{\psi}}^{\ensuremath{'}}$ and $\ensuremath{\psi}$. When the $c\overline{c}$ potential is applied to the $\ensuremath{\Upsilon}$ family, it accounts, without any readjustment of parameters, for the positions of the $2S$ and $3S$ levels and for the leptonic widths of $\ensuremath{\Upsilon}$ and ${\ensuremath{\Upsilon}}^{\ensuremath{'}}$ relative to that of $\ensuremath{\psi}$. The model does not give acceptable values of the absolute leptonic widths, a shortcoming which is ascribed to large quantum-chromodynamic corrections to the van Royen-Weisskopf formula. The calculated $E1$ rates are about twice the values observed in the $\ensuremath{\psi}$ family. This naive model is also extended with considerable success to mesons composed of one heavy and one light quark. A significant extension of the model is achieved by incorporating coupling to charmed-meson decay channels. This gives a satisfactory understanding of $\ensuremath{\psi}(3772)$ as the $1^{3}D_{1}$ $c\overline{c}$ state, mixed via open and closed decay channels to $2^{3}S$. The model has decay amplitudes that are oscillatory functions of the decay momentum; these oscillations are a direct consequence of the radial nodes in the $c\overline{c}$ parent states. These amplitudes provide a qualitative understanding of the observed peculiar branching ratios into various charmed-meson channels near the resonance at 4.03 GeV, which is assigned to $3^{3}S$. The coupling of the $c\overline{c}$ states below the charm threshold to closed decay channels modifies the bound states and leads to reduction of about 20% in $E1$ rates in comparison to those of the naive model.
843 citations
TL;DR: In this article, it was shown that the Jacobian factor in the path-integral measure, which corresponds to the Adler-Bell-Jackiw anomaly, is independent of any smooth regularization procedure of large eigenvalues of Euclidean theory.
Abstract: The Atiyah-Singer index theorem indicates that a naive unitary transformation of basis vectors for fermions interacting with gauge fields is not allowed in general. On the basis of this observation, it was previously shown that the path-integral measure of a gauge-invariant fermion theory is transformed nontrivially under the chiral transformation, and thus leads to a simple derivation of "anomalous" chiral Ward-Takahashi identities. We here clarify some of the technical aspects associated with the discussion. It is shown that the Jacobian factor in the path-integral measure, which corresponds to the Adler-Bell-Jackiw anomaly, is independent of any smooth regularization procedure of large eigenvalues of $D$ in Euclidean theory; this property holds in any even-dimensional space-time and also for the gravitational anomaly. The appearance of the anomaly and its connection with the index theorem are thus related to the fact that the primary importance is attached to the Lorentz-covariant "energy" operator $D$ and that $D$ and ${\ensuremath{\gamma}}_{5}$ do not commute. The abnormal behavior of the path-integral measure at the zero-frequency sector in the presence of instantons and its connection with spontaneous symmetry breaking is also clarified. We comment on several other problems associated with the anomaly and on the Pauli-Villars regularization method.
640 citations
TL;DR: In this article, a simple renormalization framework to carry out practical calculations in the √ √ U(1)$ theory is discussed, where the basic counterterms associated with the mass matrix of the gauge bosons and their interactions with quarks and leptons are generated and determined in a straightforward manner.
Abstract: A simple renormalization framework to carry out practical calculations in the $\mathrm{SU}{(2)}_{L}\ifmmode\times\else\texttimes\fi{}\mathrm{U}(1)$ theory is discussed. The basic counterterms associated with the mass matrix of the gauge bosons and their interactions with quarks and leptons are generated and determined in a straightforward manner. They can then be applied, in a systematic fashion, to study the radiative corrections to the various processes of interest: $\ensuremath{\mu}$ decay, $\ensuremath{\beta}$ decay, $\ensuremath{
u}$-induced reactions, and other leptonic and semileptonic processes. The role played by ${cos\ensuremath{\theta}}_{W}$ is discussed in some detail. Using the results and methods of the current-algebra formulation of radiative corrections, an effective Lagrangian is derived for $\ensuremath{\mu}$ decay in which the contributions of the heavy particles and some of the photonic corrections are reduced to a renormalization factor of the zeroth-order amplitude. This analysis determines the connection between the renormalized constants of the present framework and ${G}_{\ensuremath{\mu}}$. The corrections to the relation ${m}_{W}=\frac{{(\frac{\ensuremath{\pi}\ensuremath{\alpha}}{\sqrt{2}{G}_{\ensuremath{\mu}}})}^{\frac{1}{2}}}{{sin\ensuremath{\theta}}_{W}}$ are discussed. This leads to some relevant observations concerning certain model-dependent hadronic contributions to these corrections and their cancellation in the comparison between charged-current transitions and neutral-current processes occurring at large momentum transfers.
590 citations
TL;DR: In this paper, the authors evaluate path integrals for pure SU(2) gauge fields using Monte Carlo techniques, and show that when the string tension is fixed, the coefficient of the asymptotic linear potential between sources between sources in the fundamental representation of the gauge group decays in a manner consistent with perturbative renormalization-group prediction.
Abstract: Using Monte Carlo techniques, we evaluate path integrals for pure SU(2) gauge fields. Wilson's regularization procedure on a lattice of up to ${10}^{4}$ sites controls ultraviolet divergences. Our renormalization prescription, based on confinement, is to hold fixed the string tension, the coefficient of the asymptotic linear potential between sources in the fundamental representation of the gauge group. Upon reducing the cutoff, we observe a logarithmic decrease of the bare coupling constant in a manner consistent with the perturbative renormalization-group prediction. This supports the coexistence of confinement and asymptotic freedom for quantized non-Abelian gauge fields.
587 citations
TL;DR: In this article, the contribution of photon effective action from one-loop vacuum polarization on a general curved background manifold was calculated, and the corrections to the local propagation of photons were investigated, and it was shown that the quantum corrections introduce tidal gravitational forces on the photons which in general alter the characteristics of propagation, so that in some cases photons travel at speeds greater than unity.
Abstract: We calculate in QED the contribution to the photon effective action from one-loop vacuum polarization on a general curved background manifold, and use it to investigate the corrections to the local propagation of photons. We find that the quantum corrections introduce tidal gravitational forces on the photons which in general alter the characteristics of propagation, so that in some cases photons travel at speeds greater than unity. The effect is nondispersive and gauge invariant. We look at a few examples, including a background Schwarzschild geometry, and we argue that although these results are controversial they do not in fact exhibit any obvious inconsistency.
TL;DR: In this paper, it is argued that if the Hamiltonian of a system of charged fermions does not conserve parity, then an equilibrium electric current parallel to the value of the magnetic field can develop in such a system in an external magnetic field.
Abstract: It is argued that if the Hamiltonian of a system of charged fermions does not conserve parity, then an equilibrium electric current parallel to $\stackrel{\ensuremath{\rightarrow}}{\mathrm{B}}$ can develop in such a system in an external magnetic field $\stackrel{\ensuremath{\rightarrow}}{\mathrm{B}}$. The equilibrium current is calculated (i) for noninteracting left-handed massless fermions and (ii) for a system of massive particles with a Fermitype parity-violating interaction. In the first case a nonzero current is found, while in the second case the current vanishes in the lowest order of perturbation theory. The physical reason for the cancellation of the current in the second case is not clear and one cannot rule out the possibility that a nonzero current appears in other models.
TL;DR: In this paper, the Klein-Gordon equation for a scalar field of mass in the geometry of a rotating black hole was analyzed and it was shown that in the limit of the particle Compton wavelength much larger than the size of the black hole, the scalar fields is unstable with an $e$-folding time of
Abstract: The Klein-Gordon equation for a scalar field of mass $\ensuremath{\mu}$ is analyzed in the geometry of a rotating black hole. It is shown that in the limit $\ensuremath{\mu}M\ensuremath{\ll}1$, i.e., particle Compton wavelength much larger than the size of the black hole, the scalar field is unstable with an $e$-folding time of $\ensuremath{\tau}={(\frac{a}{M})}^{\ensuremath{-}1}24{(\ensuremath{\mu}M)}^{\ensuremath{-}8}{\ensuremath{\mu}}^{\ensuremath{-}1}$.
TL;DR: In this article, a simple solution to the vacuum field equations of general relativity in 4 + 1 space-time dimensions leads to a cosmology which at the present epoch has 3 + 1 observable dimensions in which the Einstein-Maxwell equations are obeyed.
Abstract: We show that a simple solution to the vacuum field equations of general relativity in 4 + 1 space-time dimensions leads to a cosmology which at the present epoch has 3 + 1 observable dimensions in which the Einstein-Maxwell equations are obeyed. The large ratio of the electromagnetic to gravitational forces is a consequence of the age of the Universe, in agreement with Dirac's large-number hypothesis.
TL;DR: In this paper, experimental constraints on possible lepton and quark substructure are analyzed and expressed in terms of a general formalism for describing composite particles in term of their constituents. But the authors do not consider the effect of the measured gyromagnetic ratios on the internal structure of light leptons.
Abstract: Experimental constraints on possible lepton and quark substructure are analyzed and expressed in terms of a general formalism for describing composite particles in terms of their constituents. In particular, the measured gyromagnetic ratios may very severely restrict possible internal structure of light leptons (electrons and muons) in some models. Simple expressions for hadronic $g$ values and electromagnetic radii are given in terms of their quarkgluon infinite-momentum-frame wave function. The contribution to the anomalous moment of a fermion due to internal structure is shown to vanish as the mass or inverse-size scale of the internal state becomes infinitely large.
TL;DR: In this paper, the analytic properties of the vertex functions for massless scalar and massless and massive spinor electrodynamics are investigated, and complete expressions for each vertex are obtained which contain only one nonelementary function.
Abstract: The analytic properties of the vertex functions for massless scalar and massless and massive spinor electrodynamics are investigated. First, a general tensor form for the vertex consistent with the Ward identities and free of kinematic singularities is constructed. All of the scalar functions that appear are then calculated to one-loop order in perturbation theory. It is found that in both massive and massless theories the infrared singularities appear in the longitudinal parts of the vertex. The massless theories have additional photon mass-shell singularities which appear in the transverse terms. Complete expressions for each vertex are obtained which contain only one nonelementary function.
TL;DR: In this paper, the authors study nonsingular vacuum Cauchy hypersurfaces with two isometric asymptotically flat ends connected by an Einstein-Rosen-type bridge and show that the complete initial data transform invariantly under inversion through a minimal two-surface that represents the "throat" of the geometry.
Abstract: As a first step in constructing initial data for dynamic black holes and general black-hole collisions, we study nonsingular vacuum Cauchy hypersurfaces with two isometric asymptotically flat ends connected by an Einstein-Rosen-type bridge. These hypersurfaces are assumed to be conformally flat and maximally embedded in space-time but are neither spherically symmetric nor time symmetric. Three of the four constraints are solved explicitly for suitable extrinsic curvature tensors that possess linear momentum and/or intrinsic angular momentum. The complete initial data are shown to transform invariantly, modulo the sign of the extrinsic curvature tensor, under inversion through a minimal two-surface that represents the ''throat'' of the geometry. These and other properties show that the data represent a particular epoch in the history of a dynamic black hole. We describe the relation of our data to that of the Schwarzschild and Kerr black holes. Finally, we discuss the generalization to encounters of two or more black holes.
TL;DR: In this paper, the polarization of the vacuum induced by gravitation is studied for massless fields in the region exterior to the horizon of a Schwarzschild black hole and the form of the renormalized expectation value of the stress tensor near the horizon and at infinity is discussed for each of these three states.
Abstract: The polarization of the vacuum induced by gravitation is studied for massless fields in the region exterior to the horizon of a Schwarzschild black hole. The renormalized value of $〈{\ensuremath{\varphi}}^{2}(x)〉$ is calculated according to the "covariant point-separation scheme" for each of the Boulware, Hartle-Hawking, and Unruh "vacua." The form of the renormalized expectation value of the stress tensor near the horizon and at infinity is discussed for each of these three states. It is found that the Unruh vacuum best approximates the state that would obtain following the gravitational collapse of a massive body in the sense that the expectation values of physical observables are finite, in a freely falling frame, on the future horizon and that this state is empty near infinity apart from an outgoing flux of a blackbody radiation. The response of an Unruh box is examined further in the light of the results obtained for the stress tensor. Finally it is shown by explicit solution of the linearized Einstein equations that the area of the horizon decreases at the rate expected from the flux at infinity.
TL;DR: In this article, the sensitivity of present-energy weak interactions to a strongly interacting heavy-Higgs-boson sector is discussed, and the effects are found to be small, of the order of the square of the gauge coupling times logarithms (but not powers) of the Higgs boson mass divided by the W mass.
Abstract: The sensitivity of present-energy weak interactions to a strongly interacting heavy-Higgs-boson sector is discussed. The gauged nonlinear sigma model, which is the limit of the linear model as the Higgs-boson mass goes to infinity, is used to organize and catalogue all possible heavy-Higgs-boson effects. As long as the SU(2)/sub L/ x SU(2)/sub R/ symmetry of the Higgs sector is preserved, these effects are found to be small, of the order of the square of the gauge coupling times logarithms (but not powers) of the Higgs-boson mass divided by the W mass. We work in the context of a simplified model with gauge group SU(2)/sub L/; the extension to SU(2)/sub L/ x U(1) is briefly discussed.
TL;DR: In this article, the influence of coherent forward scattering in matter upon neutrino oscillations in the three-neutrino picture is evaluated and illustrated using an oscillation solution suggested by solar and reactor data.
Abstract: We evaluate the influence of coherent forward scattering in matter upon neutrino oscillations in the three-neutrino picture. We write down the exact solution and also approximate first-order solutions that exhibit general features more transparently. Oscillation characteristics in matter that could be observed in deep-mine experiments are discussed and illustrated using an oscillation solution suggested by solar and reactor data.
TL;DR: In this paper, the SO(3,2) de Sitter group was spontaneously broken down to the Lorentz group, and the Goldstone field of the symmetry-breaking mechanism played a central role, representing the coordinates of a point in an internal anti-de Sitter space.
Abstract: The local geometrical structure of general relativity is analyzed in detail from the standpoint of a formulation of gravity as a gauge theory of the de Sitter group SO(3,2). In order to reproduce the structure of the Einstein-Cartan theory, it is essential that the SO(3,2) gauge symmetry be spontaneously broken down to the Lorentz group. In the geometrical analysis of this spontaneously broken theory, the Goldstone field of the symmetry-breaking mechanism plays a central role, representing the coordinates of a point in an internal anti-de Sitter space where the motions induced by parallel transport across space-time take place. In order to establish the connection between the SO(3,2) gauge theory and the Einstein-Cartan theory, the gravitational vierbein and spin connection are derived from the original SO(3,2) gauge fields by passing over to a set of nonlinearly-transforming fields through a redefinition involving the Goldstone field. The original SO(3,2) gauge fields have a different but equally important role: they generate pseudotranslations and rotations in the internal anti-de Sitter space under a kind of parallel transport across space-time that is called "development." Development maps curves in space-time into image curves in the internal space, and vector fields along the curves in space-time into image vector fields along the image curves. Considering development along infinitesimal closed curves in space-time leads to the proper interpretation of the effects of torsion and of curvature in terms of the nonclosure of image curves and of the rotation of image vectors with respect to their original values.
TL;DR: In this paper, an independent discussion of these field theories is given, based on a hierarchy of generalized Christoffel symbols with simple gauge transformation properties, and the necessity of certain constraints on gauge fields and parameters is easily seen.
Abstract: Free-field theories for symmetric tensor and tensor-spinor gauge fields have recently been obtained which describe massless particles of arbitrary integer or half-integer spin. An independent discussion of these field theories is given here, based on a hierarchy of generalized Christoffel symbols with simple gauge transformation properties. The necessity of certain constraints on gauge fields and parameters is easily seen. Wave equations and Lagrangians are expressed in terms of the Christoffel symbols, and the independent modes of the system are counted in covariant gauges. Minimal-coupling inconsistency and a combined system of higher-spin boson gauge fields interacting with relativistic particles is discussed.
TL;DR: It is found that the weak radiative corrections to $\ensuremath{
u}$-hadron neutral-current scattering give rise to a universal renormalization factor, which is useful in the study of radiative Corrections to many other processes of physical interest.
Abstract: Weak corrections of order $\ensuremath{\alpha}$ to $\ensuremath{
u}$-induced neutral-current phenomena are studied in the $\mathrm{SU}{(2)}_{L}\ifmmode\times\else\texttimes\fi{}\mathrm{U}(1)$ theory. Calculations are carried out using a simple renormalization framework in which ${cos\ensuremath{\theta}}_{W}=\frac{{m}_{W}}{{m}_{z}}$ exactly and amplitudes are expressed in terms of ${G}_{\ensuremath{\mu}}$, the universal constant of the weak interactions obtained from muon decay. To rigorously evaluate corrections to hadronic vertices, we employ the current-algebra formulation of radiative corrections. Our main emphasis is on large-momentum-transfer processes such as deep-inelastic scattering; however, we also discuss low-momentum transfers and $\ensuremath{
u}$-lepton interactions. We find that the weak radiative corrections to $\ensuremath{
u}$-hadron neutral-current scattering give rise to a universal renormalization factor ${\ensuremath{\rho}}_{\mathrm{Nc}}^{(\ensuremath{
u};h)}$ multiplying the overall amplitude, a correction factor ${\ensuremath{\kappa}}^{(\ensuremath{
u};h)}({q}^{2})$ multiplying ${{sin}^{2}\ensuremath{\theta}}_{W}$, and two new induced currents not present at the tree level. For nonexotic values of ${m}_{{\ensuremath{\varphi}}_{1}}$ (Higgs-scalar mass) and ${m}_{t}$ $t$-quark mass), the corrections ${\ensuremath{\rho}}_{\mathrm{Nc}}^{(\ensuremath{
u};h)}$- 1 and ${\ensuremath{\kappa}}^{(\ensuremath{
u};h)}({q}^{2})$- 1 turn out to be small over a wide range of momentum transfers. The smallness of these corrections is mainly due to the renormalization framework employed; but it is helped by a subtle partial cancellation between hadronic and bosonic contributions. Photonic corrections to the hadronic vertices are also briefly discussed in the leading-logarithm approximation of the quark-parton model. Detailed expressions for the $\mathrm{ZZ}$, $\mathrm{WW}$, $\ensuremath{\gamma}Z$, and $\ensuremath{\gamma}\ensuremath{\gamma}$ self-energies along with a discussion of the effect of large ${m}_{t}$ on these quantities are given. They play an important role in our renormalization scheme and are useful in the study of radiative corrections to many other processes of physical interest.
TL;DR: In this paper, a fully interacting effective chiral Lagrangian obeying the anomalous axial-baryon current conservation law is constructed, which displays the dependence of amplitudes on the quantum-chromodynamic vacuum angle.
Abstract: A fully interacting effective chiral Lagrangian obeying the anomalous axial-baryon-current conservation law is constructed. This Lagrangian is a generalization of one implied by the $\frac{1}{N}$ approximation. In a certain sense, the old $\ensuremath{\sigma}$ model is recovered. Our Lagrangian displays the dependence of amplitudes on the quantum-chromodynamic vacuum angle $\ensuremath{\theta}$, gives soft ${\ensuremath{\eta}}^{\ensuremath{'}}$ theorems, and hints at a possible complementarity between the instanton and $\frac{1}{N}$ approaches. We can rewrite our model in terms of a gauge-invariant gluon field.
TL;DR: A straightforward SU(3) x U(1) model in which there is effectively one new neutral current parameter (denoted by R) is shown to give the canonical neutrino neutral-current predictions for all values of R as mentioned in this paper.
Abstract: A straightforward SU(3) x U(1) model in which there is effectively one new neutral-current parameter (denoted by R) is shown to give the canonical neutrino neutral-current predictions for all values of R. For small R the ''low-energy'' theory is essentially SU(2) x U(1) while for R of the order of one it has a much richer ''low-energy'' gauge-boson mass spectrum. Even in the latter case, the predicted e-d asymmetry agrees with experiment. It is interesting that the atomic-physics parity violation depends sensitively on R.
TL;DR: In this article, the sensitivity of the Weinberg-Salam model to the heavy Higgs-boson sector was investigated, and it was shown that the sensitivity is logarithmic at one loop.
Abstract: We search for a systematic way to characterize the low-energy sensitivity of the minimal Weinberg-Salam model to a heavy-Higgs-boson sector. We find that it is convenient to view this theory as the regulated version of a nonlinear $\ensuremath{\sigma}$ model coupled to an $\mathrm{SU}{(2)}_{L}\ifmmode\times\else\texttimes\fi{}\mathrm{U}(1)$ Yang-Mills theory. Within this framework, ${M}_{H}$ acts as the regulator. Using the symmetry properties of the nonlinear theory, along with a power-counting analysis, we are able to classify low-energy observables according to their sensitivity to ${M}_{H}$. We find that, at one loop, the greatest sensitivity is logarithmic. An illustration of these ideas is provided by a calculation of the one-loop, ${M}_{H}$-dependent corrections to the natural relation $\frac{{M}_{W}}{{M}_{Z}}$ $cos\ensuremath{\theta}=1$. Finally, we discuss other possible applications of this technique.
TL;DR: In this paper, the phase structure of lattice electrodynamics in three and four dimensions using Monte Carlo simulation was studied, with special emphasis on the topological excitations of the theory.
Abstract: We study the phase structure of lattice electrodynamics in three and four dimensions using Monte Carlo simulation, with special emphasis on the topological excitations of the theory. We formulate an operational definition of a monopole and measure the density of monopoles as a function of coupling constant. In three dimensions and for strong coupling in four dimensions monopoles screen external magnetic fields. Below a critical coupling in four dimensions the external field penetrates into the bulk of the medium; this long-range correlation essentially shows that the lattice theory in weak coupling is characterized by a massless photon.
TL;DR: In this article, a restricted gauge theory is obtained as a self-consistent subset of a non-Abelian gauge theory by imposing an extra magnetic symmetry to the gauge symmetry.
Abstract: A restricted gauge theory is obtained as a self-consistent subset of a non-Abelian gauge theory by imposing an extra magnetic symmetry to the gauge symmetry. The theory describes the dual dynamics between the color isocharges (i.e., the electric charges) and the topological charges (i.e., the magnetic charges) of the non-Abelian symmetry, and contains two potentials, the electric and the magnetic potentials, in a dual-symmetric way. The topological charge is identified as the dual of the Noether charge of the magnetic symmetry of the theory. A possible role of the restricted chromodynamics for quark confinement in quantum chromodynamics is speculated.
TL;DR: The classical theory of the geometrical string is developed as the theory of a simple, surface-forming timelike bivector field in an arbitrary background space-time as mentioned in this paper.
Abstract: The classical theory of the geometrical string is developed as the theory of a simple, surface-forming timelike bivector field in an arbitrary background space-time. The stress-energy tensor for a perfect dust of such strings is written down, and the conservation laws for such a dust, as well as the equations of motion of the string, are derived from the vanishing of the divergence of the stress-energy tensor. (The boundary conditions for the open string are also derived from the junction conditions for the stress-energy tensor in Appendix A.) The generalization of this model to null strings, and to a perfect fluid of strings, are discussed, and will form the subject of the second and third papers in this series. The problem of a fully general-relativistic string theory, and an alternate approach to the string, based upon defining an acceleration tensor for two- (and higher) dimensional subspaces, are also discussed.
TL;DR: In this paper, the pseudoscalar and photon couplings of the states associated with up to two orbital or one radial excitation in the nonrelativistic quark model are used to generate a set of baryon amplitudes which resolve the problem of "missing" resonances by essentially decoupling a very large number of states from partial-wave analyses and leaving those resonances which remain in remarkable correspondence to the observed states in both their masses and decay amplitudes.
Abstract: Quark models of hadrons are tested in a very limited way when only their spectroscopy is compared with experiment; at least equally important tests arise from examining the predicted internal structure of the hadrons via analysis of their decay amplitudes. We present here a compilation of one of the most extensive calculations of baryon amplitudes to date, encompassing the pseudoscalar and photon couplings of the states associated with up to two orbital or one radial excitation in the nonrelativistic quark model. These amplitudes are then combined with the baryon compositions predicted by a quark model incorporating some of the features expected to arise from quantum chromodynamics. The result is to generate a set of baryon amplitudes which (1) resolve the problem of "missing" resonances by essentially decoupling a very large number of states from partial-wave analyses and (2) leave those resonances which remain in remarkable correspondence to the observed states in both their masses and decay amplitudes.