Gamov states in the generator coordinate method

Starting from the generator coordinate theory, a method is developed for calculating-decay widths within a microscopic dynamical theory. Antisymmetrization is taken into account exactly between all nucleons of the decaying system. For illustration, the method is applied to the-decay of⁸Be and²⁰Ne.     

Hydrodynamics of superionic conductors

Using the Mori method we present a rigorous hydrodynamic theory for the collective excitations in superionic conductors at low frequencies and long wavelengths. By means of static and dynamic linear response theory all microscopic quantities of the theory are expressed as derivatives of the free energy or as transport coefficients. Explicit expressions for the dispersion and the damping of the modes and for the density correlation function are worked out for high-symmetry directions and numerically evaluated for-AgI. In particular we show that the two non-propagating modes can give rise to a small central component (width~k ², constant intensity) and a broad central component (constant width fork0, intensity ~k ²) in scattering spectra. Extrapolating our theory to larger wave vectors we offer a new explanation for the broad central component found recently in neutron scattering spectra of-AgI.     

On the Relation Between U q (sl(2)) Vertex Operators and q-Zonal Functions

We show how the states constructed from the action of the modes of bosonized vertex operators that intertwine U modules are related toq -zonal functions.     

Very-short-wavelength collective modes in fluids

The existence of very-short-wavelength collective modes in fluids is discussed. These collective modes are the extensions of the five hydrodynamic (heat, sound, viscous) modes to wavelengths of the order of the mean free path in a gas or to a fraction of the molecular size in a liquid. They are computed here explicitly on the basis of a model kinetic equation for a hard sphere fluid. At low densities all five modes are increasingly damped with decreasing wavelength till each ceases to exist at a cutoff wavelength. At high densities the extended heat mode softens very appreciably for wavelengths of the order of the size of the particles and becomes a diffusion-like mode that persists till much shorter wavelengths than the other modes. Except for the shortest wavelengths these collective modes and in particular the heat mode dominate the dynamical structure factorS(k, ) for all densities. The agreement of the theory with experimentalS(k, ) of liquid Ar seems to imply that very-short-wavelength collective modes also occur in real fluids.     

On the consistent solution of the gap-equation for spontaneously brokenλΦ 4-theory

We present a self-consistent solution of the finite temperature gap-equation for ⁴ theory beyond the Hartree-Fock approximation using a composite operator effective action. We find that in a spontaneously broken theory not only the so-called daisy and superdaisy graphs contribute to the resummed mass, but also resummed non-local diagrams are of the same order.herby@lapphpl.in2p3.fr     

The effective action of a BPS Alice string

Recently a BPS Alice string has been found in a \(U(1)\times SO(3)\) gauge theory coupled with three charged complex scalar fields in the triplet representation (in JHEP 1709:046 arXiv:1703.08971 [hep-th], 2017). It is a half BPS state preserving a half of the supercharges when embedded into a supersymmetric gauge theory. In this paper, we study zero modes of a BPS Alice string. After presenting U(1) and translational zero modes, we construct the effective action of these modes. In contrast to a previous analysis of the conventional Alice string for which only large distance behaviors are known, we can exactly perform a calculation in the full space thanks to the BPS properties.     

One-loop surface tension on a boundary inλφ 4 theory

We calculate quantum corrections to the vacuum energy in ⁴ theory with a tachyonic mass term in a half space, where the scalar field is required to satisfy the Dirichlet boundary condition on the surface. It is found that the one-loop self-energy diagram includes a finite energy portion, representing a repulsive surface tension on the boundary.     

Ab initio phonon dispersion relations of $\mathsf{\alpha}$-Ga

We present the ab initio phonon dispersion relations of -Ga. The calculations are carried out within density functional perturbation theory by using either norm-conserving pseudopotential and 4s and 4p electrons in the valence or ultrasoft pseudopotential and 3d electrons in the valence as well. The inclusion of 3d electrons in the valence turned out to be necessary to better reproduce the experimental frequencies of the stretching modes of the Ga₂ dimers present in the -Ga structure.Received: 29 July 2003, Published online: 19 November 2003PACS: 63.20.Dj Phonon states and bands, normal modes, and phonon dispersion - 71.15.Nc Total energy and cohesive energy calculations - 71.15.Mb Density functional theory, local density approximation, gradient and other corrections     

Hartree-Fock theory of spiral magnetic order in the 2-d Hubbard model

The magnetic order in the 2-d Hubbard model is investigated within Hartree-Fock theory. For the class of states with uniform particle density and spiral arrangement of spins the phase diagram is obtained by minimizing the free energy. At zero temperature and large Hubbard interactionU there is a continuous transition from the antiferromagnetic solution at half filling over a spiral state of increasing wavelength along the diagonal of the lattice to the ferromagnetic state at doping _c 2t/U. At finite temperatureT, the antiferromagnetic state remains stable for doping smaller than _AF 2T/U. For intermediate values ofU and finite doping there exists also a phase with a spiral wave vector of the form Q=(Q, ).     

Monopole charges for arbitrary compact gauge groups and Higgs fields in any representation

The topological invariants of monopoles are described for an arbitrary compact gauge groupG and Higgs field in any representation. The results generalize those obtained recently for compact and simply connectedG and in the adjoint representation. The cases when the residual symmetry group isH=U(1) orH=U(3) are worked out explicitly. This latter is needed to accommodate fractional electric charge with monopoles having one Dirac unit magnetic charge.The general theory is illustrated on the SU(5) monopole.     

Mind,matter, and quantum mechanics

A theory of psychophysical phenomena is proposed. It resolves simultaneously four basic problems of science, namely the problems of the connections between:(1) mind and matter,(2) quantum theory and reality,(3) relativity theory and becoming, and (4) relativity theory and Bell's theorem.This work was supported by the Director, Office of Energy Research, Office of High Energy and Nuclear Physics, Division of High Energy Physics of the U.S. Department of Energy under Contract W-7405-EN-G-48.     

Almost positive perturbations of positive selfadjoint operators

LetA be a positive selfadjoint operator and letB be a symmetric perturbation ofA. We establish sufficient conditions for the essential selfadjointness ofA+B on domains whereA is essentially selfadjoint. The results have application to the ⁴ field theory in two space-time dimensions.Supported in part by the U.S. Air Force under Grant AFOSR 68-1453 MOD C.     

Dispersion in momentum space and the existence ofU(t,t')

The operatorU(t,t') giving transition probabilities between finite times or connecting free and interacting fields does not exist (apart from the ultraviolet divergence problem) because of the 3-translation invariance of current quantum field theory. To remedy this, the idealization that one has an infinite timeT = to prepare initial, or measure final,n-particle momentum eigenstates is discarded here. It is shown that random space-time (which itself eliminates ultraviolet divergences from field theory) implies and fixes uniquely a random momentum space if free particle momentaK are determined by time-of-flight measurements withT < . In particular, the dispersion ofK m/T, where is the space-time dispersion andm is the particle mass. Stochastic momentum space is incorporated into field theory in a preliminary way; because 3-translation form-invariance is slightly violated, the unitaryU-operator expressed as the usualT-exponential exists and the limitU S ast ,t' – is welldefined withoutad hoc tricks like the adiabatic cut-off. A frame-dependence is necessarily introduced into fields andU-operator, and the transformation properties expressing Lorentz covariance are of the same more general type encountered in previous work on quantum field theory over stochastic spacetime.     

Ohmic selection in open coaxial resonators: An experimental study

A study of ohmic selective properties of open coaxial cylindrical resonators has been conducted experimentally and compared with theory. The resonator consists of an inner cylinder made of silicon carbide symmetrically located inside an outer cylindrical, tube shaped waveguide. Several fundamental TE modes were identified over the range 9 to 17 GHz through measurements of the resonant frequencies and the associated quality factors. Mode discrimination is achieved both by exploring selective ohmic effects and examining the electrodynamical properties of the coaxial cylindrical waveguide. The effectiveness of a silicon carbide coaxial insert in providing ohmic mode selection is demonstrated in that the totalQ factors of TE _mp modes with radial indexp2 become well below the quality factors for surface TE _m1 modes. It has been verified that both structure and number of resonant modes are strongly dependent on the diameter and the resistivity of the coaxial insert.