Showing papers on "Spin-½ published in 1983"
TL;DR: In this paper, the spin and statistics of solitons in the (2 + 1)- and (3 + 1) nonlinear sigma models are considered. And for the 3 + 1 dimensions, the usual spin-statistics relation is demonstrated, using the linking-number interpretation of the Hopf invariant and the use of suspension.
Abstract: The spin and statistics of solitons in the (2 + 1)- and (3 + 1)-dimensional nonlinear sigma models is considered. For the (2 + 1)-dimensional case, there is the possibility of fractional spin and exotic statistics; for 3 + 1 dimensions, the usual spin-statistics relation is demonstrated. The linking-number interpretation of the Hopf invariant and the use of suspension considerably simplify the analysis.
545 citations
Book•
03 Oct 1983
TL;DR: In this paper, Faddeev Equations and other Coupling Schemes and Spuriosities were used for the transition of a two-nucleon system to a three-body force.
Abstract: 1 Elements of Potential Scattering Theory- 11 The Moller Wave Operator- 12 The Cross Section- 13 Resolvent Operators and Green's Functions- 14 Asymptotic Behaviour of the Scattering Wave Function- 15 The S-, T-, and K-Matrices- 16 S-Matrix Pole Trajectories- 17 Criteria for Divergence or Convergence of the Neumann Series- 2 Scattering Theory for the Two-Nucleon System- 21 Density Matrices for the Initial and Final State- 22 The General Spin Observable- 23 The Wolfenstein Parametrisation of the Scattering Amplitude- 24 Examples for Spin Observables- 241 Polarisation- 242 Asymmetry- 243 Depolarisation- 244 Spin Correlation Parameters- 25 Partial-Wave Decomposition- 26 Standard S-Matrix Representations- 27 Numerical Methods- 271 Coordinate Space- 272 Momentum Space- 273 Pade Method- 3 Three Interacting Particles- 31 Channels- 32 The Fundamental Set of Lippmann-Schwinger Equations- 33 Faddeev Equations and Other Coupling Schemes- 331 Faddeev Equations- 332 Faddeev Equations in Differential Form and the Asymptotic Behaviour of the Faddeev Amplitudes- 333 Other Coupling Schemes and Spuriosities- 34 Transition Operators- 341 AGS-Equations- 342 Unitarity- 343 Multiple Scattering Series- 344 Identical Particles- 35 Examples of Numerical Studies in Few-Nucleon Scattering- 351 Lovelace Equations- 352 Kinematical Curves- 353 Selected Numerical Studies- 36 The Three-Nucleon Bound State- 361 The Faddeev Equations with a Three-Body Force- 362 Momentum Space Representation- 363 A Technical Remark- 364 Physical Remarks About the Triton- 365 Appendix: The Recoupling Coefficient in Momentum Space- 4 Four Interacting Particles- 41 The Fundamental Set of Lippmann-Schwinger Equations- 42 Coupled Equations in Dummy Variables- 43 Yakubovsky Equations- 44 AGS-Equations for Transition Operators- 45 Remarks on Equations of Higher Connectivity- References- Reviews, Monographies, and Conferences
430 citations
TL;DR: In this article, the Bloch vector model has been used for the analysis of high-resolution NMR spectroscopy, and the main areas of application are signal assignment, sensitivity enhancement, and selective excitation of individual resonances.
Abstract: The introduction of Fourier transform methods has not only remarkably enhanced the sensitivity of high-resolution NMR spectroscopy, thus allowing measurements to be made on less sensitive nuclei of the Periodic Table, but also has paved the way for the development of a large number of new experimental techniques. On the one hand, procedures already known have been improved and can now be performed more rapidly, and, on the other, completely new experimental approaches have become available. This situation resulted mainly from the introduction of programmable pulse transmitters and the separation of the experiment into preparation, evolution, and detection. In particular, the concept of two-dimensional spectroscopy has opened up new possibilities important for the analysis of complicated spectra and is able to provide information previously not accessible. As elsewhere, optimum application of the techniques and correct interpretation of the results require sound understanding of the underlying physical principles. Since a rigorous mathematical treatment is complicated and does not necessarily improve the comprehensibility, this article attempts to give an illustrative presentation of the new pulse techniques within the framework of the Bloch vector model. After a short introduction covering the basic principles, one-dimensional pulse techniques that can be applied using standard experimental equipment are dealt with. The main areas of application are signal assignment, sensitivity enhancement for measurements on less abundant nuclei, and selective excitation of individual resonances. Subsequently, the various techniques of two-dimensional NMR spectroscopy are treated: these enable shift correlations for different types of nuclei to be made, the presentation of spin multiplets without overlap, and the analysis of geometrical relations as well as of chemical exchange phenomena.
336 citations
TL;DR: In this paper, the algebraic Bethe ansatz is constructed for the GL(n) invariant transfer matrices with arbitrary GL(N) spin, which can be interpreted as an integrable discrete approximation of vector or matrix nonlinear Schrodinger models.
Abstract: The algebraic Bethe ansatz is constructed for the GL(N) invariant transfer matrices with arbitrary GL(N) spin. For this purpose the notion of vacuum subspace is introduced. It is shown that the GL(N) magnet can be interpreted as an integrable discrete approximation of vector or matrix nonlinear Schrodinger models or of the quantum N-wave system.
296 citations
199 citations
TL;DR: On etudie la mecanique lagrangienne des particules sans masse a spin, basee sur l'interpretation que le spin correspond au deplacement dans des directions complexes.
Abstract: On etudie la mecanique lagrangienne des particules sans masse a spin, basee sur l'interpretation que le spin correspond au deplacement dans des directions complexes
166 citations
TL;DR: In this paper, the authors used time-reversal pulse sequences to generate all lines in phase in order to ensure that overlapping lines add constructively and to enhance sensitivity, up to 22-quantum 1H absorption in solid adamantane is observed.
Abstract: Multiple‐quantum NMR has typically been observed in small groups of spins in isolated molecules. Due to the profusion of spin transitions in a solid, individual lines are unresolved. Excitation of high quantum transitions by normal schemes is thus difficult. To ensure that overlapping lines add constructively and to enhance sensitivity, time‐reversal pulse sequences are used to generate all lines in phase. Up to 22‐quantum 1H absorption in solid adamantane is observed.
130 citations
128 citations
TL;DR: In this article, the Bethe ansatz equations of the XXZ model in the antiferromagnetic region were analyzed without assuming a priori the existence of strings, and it was shown that strings are only particular solutions of these equations.
126 citations
124 citations
TL;DR: In this article, it was shown that the finite-temperature transition in 4-dimensional SU(N) gauge theories is in the universality class of 3-dimensional ZN spin models.
TL;DR: In this article, a general theoretical description of double frequency (df) pulsed NMR experiments on multilevel spin systems is presented using the theory of Shirley for time dependent Hamiltonians.
Abstract: Multiple quantum effects in double frequency (df) pulsed NMR experiments on multilevel spin systems are studied. In these experiments, the spin systems are irradiated by two rf fields, applied simultaneously. A general theoretical description of these experiments is presented using the theory of Shirley for time dependent Hamiltonians. Multiphoton resonance conditions are given and time independent fictitious spin‐1/2 Hamiltonians are derived using his perturbation theory treatment. With these Hamiltonians, the evolution of the spin systems during df irradiation is approximated. The example of df NMR experiments on an I=1/2 spin system is discussed. High order perturbation theory is developed to describe the time evolution of this spin system at a three photon resonance. Accurate computer calculations are performed to examine this time evolution. Df NMR experiments are performed on the single 31P(I=1/2) transition of phosphoric acid to check the theoretical results. The three photon resonance condition fo...
TL;DR: Two-dimensional double quantum 1H NMR spectra are recorded for a protein and it is established whether amide and beta-protons belong to the same spin system or not, degeneracy of beta-proton chemical shifts can be demonstrated, and glycine amide protons can be distinguished from all others.
TL;DR: In this paper, the authors simplify the quenching prescription for large N reduced spin models by introducing twisting matrices of 't Hooft, and eliminate the integral over the quENched random variables.
TL;DR: Galactic halos of massive fermions, of arbitrary half integer spin, or of massive bosons are considered in this article, and the results show that the fermion with spin s should have a mass m ∼- 10 eV /c 2 /(2s + 1) 1 4, while the bosons a mass in the range from 10eV/c2 to 10−24eV / c2.
TL;DR: In this paper, the authors discuss the renormalization prescription for fermions at finite temperature and describe the procedure for calculating radiative corrections, showing that there is a lack of explicit Lorentz invariance, and the absorption of soft photons from the background heat bath.
Abstract: We discuss the renormalization prescription for fermions at finite temperature and describe the procedure for calculating radiative corrections. Novel features arise, such as a lack of explicit Lorentz invariance, $\frac{1}{{k}^{2}}$ singularities, and the absorption of soft photons from the background heat bath. The methods are illustrated by explicit calculation of the electron renormalization and the radiative corrections to $H\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}$ (with $H$ being spin zero) in finite-temperature QED.
TL;DR: In this paper, the internal spin structure of the nucleon has been studied in the context of deep inelastic scattering, which has played a central role in establishing the quark-parton theory of the composition of hadrons and of quantum chromodynamics (QCD).
Abstract: The study of the structure of the proton and neutron through deep inelastic scattering, initially with electrons but subsequently with muons and neutrinos as well, has played a central role in establishing the quark-parton theory of the composition of hadrons and of quantum chromodynamics (QCD). One important aspect of these theoretical and experimental developments is the two spin-dependent structure functions, which are independent of the two spin-averaged structure functions and define the internal spin structure of the nucleon. Since both quarks and gluons possess spin and the forces between them are spin dependent, we can expect important information on these forces and on nucleon structure to be obtained through the study of the spindependent aspects of the nucleon wave function, as has been the case before in atomic and nuclear physics.
TL;DR: Experiments have been completed which demonstrate the greatly enhanced sensitivity of the multiple quantum version of the NMR spin echo diffusion experiment as mentioned in this paper, particularly well suited to studies of anisotropic diffusion where the presence of dipolar couplings may make the standard experiment technically infeasible.
Abstract: Experiments have been completed which demonstrate the greatly enhanced sensitivity of the multiple quantum version of the NMR spin echo diffusion experiment. These experiments are particularly well‐suited to studies of anisotropic diffusion where the presence of dipolar couplings may make the standard experiment technically infeasible. (AIP)
TL;DR: In this paper, the influence of 13C-1H dipole-dipole coupling on 13C spin diffusion was investigated by determining spectral overlap in the 13C system, and 2D 13C spectra were obtained for several values of mixing time τm and compared with spectra calculated in the limit of nearest neighbor coupling.
Abstract: Two‐dimensional exchange spectroscopy of natural abundance 13C–13C spin diffusion in solid adamantane illustrates the influence that 13C–1H dipole–dipole coupling exerts on 13C spin diffusion by determining spectral overlap in the 13C system. 2D 13C spectra were obtained for several values of mixing time τm and compared with spectra calculated in the limit of nearest‐neighbor coupling. Good agreement is obtained for short τm, during which the equilibration of neighboring spins dominates. For longer τm, slower spin diffusion that is not acounted for by the simple model is seen; after nearest‐neighbor spins equilibrate, communication over larger distances produces further mixing. It is possible to modify spin diffusion rates by altering experimental conditions, e.g., magic‐angle spinning, low‐power 1H decoupling, or spin locking 13C in the rotating frame during τm.
TL;DR: On montre qu'une extension naturelle du formalisme hydrodynamique de la mecanique quantique for une particule de Schrodinger pour inclure des ecoulements tourbillonnaires conduit au formalistique hydrodynamic de la MECANIQUE as mentioned in this paper.
Abstract: On montre qu'une extension naturelle du formalisme hydrodynamique de la mecanique quantique pour une particule de Schrodinger pour inclure des ecoulements tourbillonnaires conduit au formalisme hydrodynamique de la mecanique quantique pour une particule a spin
TL;DR: In this article, the spin-wave response of the Ising-like antiferromagnetic chain compounds CsCo${\mathrm{Br}}_{3}$ and CsCl${Cl}$ has been studied by inelastic neutron scattering.
Abstract: The spin-wave response of the $S=\frac{1}{2}$ Ising-like antiferromagnetic chain compounds CsCo${\mathrm{Br}}_{3}$ and CsCo${\mathrm{Cl}}_{3}$ has been studied by inelastic neutron scattering. The asymmetry at low temperatures of the line shape of the spin-wave continuum is not correctly predicted by the existing theory of isolated chains to first order in the transverse exchange interaction. The effective spin Hamiltonian for a chain has been rederived and shown to include a slow internal staggered field from exchange mixing that influences the rapid spin fluctuations. Three-dimensional correlations are shown to be important above but close to N\'eel temperature. The first-order calculation of Ishimura and Shiba has been extended to include these effects and numerical calculations made for $0lTl\frac{J}{{k}_{B}}$. A good account is obtained of the spin-wave continuum and its temperature dependence. The results show that the highly asymmetric line shape arises from local staggered fields which vary on a much slower time scale than the transverse spin motion, and whose effect decreases with increasing temperature in the manner expected for the decay of the intrachain and interchain correlations. An improved and simplified account of the Zeeman ladder as seen in the Raman scattering at low temperatures has also been obtained.
TL;DR: Unitary representations of the infinite parameter group Diff(R/sup 3/) are presented which describe particles with spin as well as tightly bound composite particles. as mentioned in this paper support the idea that the group can serve as a ''universal group'' for quantum theory.
Abstract: Unitary representations of the infinite parameter group Diff(R/sup 3/) are presented which describe particles with spin as well as tightly bound composite particles. These results support the idea that Diff(R/sup 3/) can serve as a ''universal group'' for quantum theory.
TL;DR: In this article, the magnetic behavior of exchange-coupled closed chains (rings) of increasing length made of two alternating spin sublattices S a = 1 2, S b = 1.
TL;DR: In this paper, the transverse susceptibility of a one-dimensional spin S Ising system can be calculated by combining linear response theory with the transfer matrix technique, and closed form expressions for infinite chains are obtained for S = 1/2 and S=1.
Abstract: It is shown that the transverse susceptibility of a one-dimensional spin S Ising system can be calculated by combining linear response theory with the transfer matrix technique. Closed form expressions for infinite chains are obtained for S=1/2 and S=1, and numerical results are displayed for S=1/2 to S=5/2.
TL;DR: In this article, the inner hysteresis loops of the high spin ⇄ low spin transition of [Fe(bt)2(NCS)2] were measured by magnetic susceptibility measurements in two different preparations and in a mechanically treated (ball mill) sample.
Abstract: The hysteresis in the high spin ⇄ low spin transition of [Fe(bt)2(NCS)2] (bt=2,2′‐bi‐2‐thiazoline) has been studied by magnetic susceptibility measurements in two different preparations and in a mechanically treated (ball mill) sample. From the measurement of two inner hysteresis loops and a comparison with Everett’s theorems for hysteresis effects, it could be established that independent domains (i.e., groups of complex molecules of like spin that can only change their state simultaneously) participate in the spin transition in the unperturbed sample. The domains were found to be no longer independent in the milled sample. This property may result from a different limitation in the size of the domains caused by lattice defects as compared to the unperturbed sample.
TL;DR: In this article, techniques for the recognition of specific spin patterns in complex overlapping proton NMR spectra are introduced based on the efficient and selective excitation of high-order multiple quantum coherence in systems of specified coupling network topology.