Today's View on Strangeness

There are several different experimental indications, such as the pion-nucleon sigma term and polarized deep-inelastic scattering, which suggest that the nucleon wave function contains a hidden s bar s component. This is expected in chiral soliton models, which also predicted the existence of new exotic baryons that may recently have been observed. Another hint of hidden strangeness in the nucleon is provided by copious phi production in various N bar N annihilation channels, which may be due to evasions of the Okubo-Zweig-Iizuka rule. One way to probe the possible polarization of hidden s bar s pairs in the nucleon may be via Lambda polarization in deep-inelastic scattering.Comment: 8 pages LaTeX, 10 figures, to appear in the Proceedings of the International Conference on Parity Violation and Hadronic Structure, Grenoble, June 200

Critical Analysis of Theoretical Estimates for BB to Light Meson Form Factors and the B→ψK(K∗)B \to \psi K(K^{\ast}) Data

We point out that current estimates of form factors fail to explain the non-leptonic decays $B \to \psi K(K^{\ast})$ and that the combination of data on the semi-leptonic decays $D \to K(K^{\ast})\ell \nu$ and on the non-leptonic decays $B \to \psi K(K^{\ast})$ (in particular recent po\-la\-ri\-za\-tion data) severely constrain the form (normalization and $q^2$ dependence) of the heavy-to-light meson form factors, if we assume the factorization hypothesis for the latter. From a simultaneous fit to \bpsi and \dk data we find that strict heavy quark limit scaling laws do not hold when going from $D$ to $B$ and must have large corrections that make softer the dependence on the masses. We find that $A_1(q^2)$ should increase slower with \qq than $A_2, V, f_+$. We propose a simple parametrization of these corrections based on a quark model or on an extension of the \hhs laws to the \hl case, complemented with an approximately constant $A_1(q^2)$. We analyze in the light of these data and theoretical input various theoretical approaches (lattice calculations, QCD sum rules, quark models) and point out the origin of the difficulties encountered by most of these schemes. In particular we check the compatibility of several quark models with the heavy quark scaling relations.Comment: 48 pages, DAPNIA/SPP/94-24, LPTHE-Orsay 94/1

Multiple WLW_L Production from Inelastic WLWLW_L W_L Scattering at s^≫MH\sqrt{\hat{s}} \gg M_H

We explore the inelastic production of multiple longitudinal weak bosons as a manifestation of a strongly interacting symmetry breaking sector. By analogy with QCD, final states with large multiplicities are expected to occur not far above the energy scale of the lowest resonances of the underlying strong theory. We consider the feasibility of observing such phenomena in the environment of a very high energy hadron collider.Comment: 23 pages, Latex, 4 figures in separate postscript file, UCLA Report 92/TEP/4

Anharmonic effects in the coherent scattering of neutrons by crystals : A formal treatment of shift and width of the peaks in the scattering spectrum

As predicted by harmonic theory the outgoing inelastic spectrum of neutrons, scattered coherently by a single crystal, for a particular angle of scattering consists of a number of delta-function peaks superposed on a continuous background. The peaks correspond to one-phonon processes in which one phonon is absorbed or emitted by the neutron; the background corresponds to multi-phonon processes. When anharmonic forces are present the delta-function peaks are broadened into finite peaks and are shifted relative to those predicted in the harmonic approximation. These anharmonic effects are treated by means of many particle perturbation theory, in which the anharmonic part of the Hamiltonian is considered as the perturbation (phonon-phonon interaction). Use has been made of diagrams for representing the various matrix elements. Since the one-phonon peaks are considered as separate from the background without confining oneself to lowest order perturbation theory, the treatment is restricted to the case where the line width of a phonon state is small with respect to the energy of the phonon also for strong coupling between the phonons. In this connection the results obtained are expected to be valid only in the temperature range from absolute zero up to temperatures not much higher than the Debye temperature. For these temperatures the influence of two-phonon processes on the line shape may be neglected. An expansion for calculating the line shift and line width in powers of u/d and in terms of simple connected diagrams is obtained (u is the average atomic displacement, d is the smallest interatomic distance in the crystal). Formulae, which express the shift and width in the parameters of the lattice, are given valid to order (u/d2

Influence of electron-phonon interaction on the scattering of neutrons by conducting crystals

The theory of the influence of phonon-phonon interactions on the location and width of the one-phonon peaks in the spectrum of inelastically scattered neutrons by single crystals, as developed earlier1), is extended to the case of metals to include the interaction between phonons and conduction electrons. Expressions are derived for the shift and width as a result of electron-phonon coupling and estimates are given for these quantities. In general the influence of electron-phonon interaction on the line shape of the scattering peaks will be small

MANY-PARTICLE THEORY OF INTERACTING PHONONS IN A CRYSTAL

Many-particle perturbation theory and diagram techniques are used to examine the effects of phonon-phonon interactions in an ideal insulating crystal. The perturbation theory and diagram techniques are introduced, and are used to obtain expressions for the free energy of an anharmonic crystal, correlation functions, thermal averages, the one-phonon Green function, and phonon lifetime and self-energy. Lattice thermal conductivity and the coherent scattering of thermal neutrons by nuclei in a perfect, single crystal are also treated. (D.C.W.