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The lineal-path function L(z) gives the probability of finding a line segment of length z entirely in one of the phases of a disordered multiphase medium. We develop an exact methodology to determine L(z) for the particle phase of systems of overlapping particles, thus providing a measure of particle clustering in this prototypical model of continuum percolation. We describe this procedure for systems of overlapping disks and spheres with a polydispersivity of sizes and randomly aligned equal-sized overlapping squares. We also study the effect of polydispersivity on the range of the lineal-path function. We note that the lineal-path function L(z) is a rigorous lower bound on the two-point cluster function C 2 (z), which is not available analytically for overlapping particle models for spatial dimension d 2. By evaluating the second derivative of L(z), we then evaluate the chord-length distribution function for the particle phase. Computer simulations that we perform are in excellent a...

Colossal magnetoresistance in metallic oxides such as R1−xXxMnO3 (where R = La,

We present a new determination of f Ds using 5 million e + e \Gamma ! cc events obtained with the CLEO II detector. Our value is derived from our new measured ratio \Gamma(D + s ! ¯ + )=\Gamma(D + s ! OEß + ) = 0:173 \Sigma 0:021 \Sigma 0:031. Using B(D + s ! OEß + ) = (3:6 \Sigma 0:9)%, we extract f Ds = (280 \Sigma 17 \Sigma 25 \Sigma 34) MeV. We compare this result with various model calculations. PACS number(s): 1320.Fc, 13.20.-v M. Chadha, 1 S. Chan, 1 G. Eigen, 1 J. S. Miller, 1 C. O'Grady, 1 M. Schmidtler, 1 J. Urheim, 1 A. J. Weinstein, 1 F. Wurthwein, 1 D. W. Bliss, 2 G. Masek, 2 H. P. Paar, 2 S. Prell, 2 V. Sharma, 2 D. M. Asner, 3 J. Gronberg, 3 T. S. Hill, 3 D. J. Lange, 3 R. J. Morrison, 3 H. N. Nelson, 3 T. K. Nelson, 3 D. Roberts, 3 A. Ryd, 3 R. Balest, 4 B. H. Behrens, 4 W. T. Ford, 4 H. Park, 4 J. Roy, 4 J. G. Smith, 4 J. P. Alexander, 5 R. Baker, 5 C. Bebek, 5 B. E. Berger, 5 K. Berke...

From an investigation of the optical conductivity of FeSi single crystals using FTIR spectroscopy in the frequency range from 30 to 20000 cm−1 we conclude that the transverse effective charge of the Fe and Si ions is approximately 4e. Of the five optical phonons which are allowed by symmetry we observe only four, three of which have a Fano line shape presumably resulting from an interaction of these modes with the electronic continuum. We show that the large oscillator strength of the phonons results from a relatively weak coupling (λ ≈ 0.1) of the lattice degrees of freedom to an electronic resonance above the semiconductor gap, which is also responsible for the large electronic polarizability (ǫ ∞ ≈ 200) of the medium.

The abundance of diffractive reactions observed at HERA indicates the presence of multiple interactions in DIS. These interactions are analysed, first in a qualitative way, in terms of QCD Feynman diagrams. Then a quantitative

VJe describe the underlying concept and experimental demonstration of the basic building bloclts of a scalable quantum information processor archikcture using trapped ion-clubits. The trap structure is divided into many subregions. In eacl~ several ion-qubits can be trapped in complete isolation from all the other ion-qubits in the system. In a particular subregion, ion-qubits can either be st,ored as memory or subjected to individual rotations or multi-qubit gates. The ion-qubits are'guided through the array by appropriately switching control electrode potentials. Excess energy that is gained through the motion of ion-qubits in the array or other heating mecha.nisrr~s can be removed by sympathetic cooling of the ion-qubits with another ion species. The proposed architecture can be used in a highly parallel fashion, an imporlanl prerequisite for fault-tolerant quantum computation.

Data collected by the H1 detector in the years 1994 to 1997 have been used to search for a signal of diffractively produced \Upsilon (\Upsilon(1S ), \Upsilon(2S ), \Upsilon(3S )) decaying into two muons. The cross section for exclusive photoproduction at an average photon proton centre-of-mass energy of 160 GeV is determined to be oe(fl p ! \Upsilon p) \Theta BR(\Upsilon ! ¯ + ¯ \Gamma ) = 16 \Sigma 8 \Sigma 4 pb (H1 preliminary). Abstract: 574 Parallel sessions: 7,5 Plenary sessions: 9,7 Introduction Measurements of diffractive photoproduction of J=/ mesons at HERA demonstrate cross sections of the order of 100 nb [1] at a photon proton centre-of-mass energy of 100 GeV. Good progress was made in describing the production properties within the framework of perturbative QCD [2, 11]. Predictions from such models lead to a cross section for \Upsilon production about three orders of magnitude lower. Since a recent measurement of inclusive photoproduction of b quarks [3] yields a hig...

We have studied semileptonic B meson decays with a P-wave charm meson in the final state using 3:29 \Theta 10 6 B ¯ B events collected by the CLEO II detector at the Cornell Electron-positron Storage Ring. We find a value for the exclusive semileptonic product branching fraction: B(B \Gamma ! D 0 1 ` \Gamma ¯ ` )B(D 0 1 ! D + ß \Gamma ) = (0:373 \Sigma 0:085 \Sigma 0:052 \Sigma 0:024)% and an upper limit for B(B \Gamma ! D 0 2 ` \Gamma ¯ ` )B(D 0 2 ! D + ß \Gamma ) ! 0:16% (90% C.L.). These results indicate that at least 20% of the total B \Gamma semileptonic rate is unaccounted for by the observed exclusive decays, B \Gamma ! D 0 ` \Gamma ¯ , B \Gamma ! D 0 ` \Gamma ¯ , B \Gamma ! D 0 1 ` \Gamma ¯ , and B \Gamma ! D 0 2 ` \Gamma ¯ . (Submitted to Physical Review Letters) A. Anastassov, 1 J. E. Duboscq, 1 D. Fujino, 1;a K. K. Gan, 1 T. Hart, 1 K. Honscheid, 1 H. Kagan, 1 R. Kass, 1 J. Lee, 1 M. B. Spencer, 1 M. S...

We propose a model for statistically inhomogeneous two-phase random media, including functionally graded materials, consisting of inhomogeneous fully penetrable (Poisson distributed) spheres. This model can be constructed for any specified variation of volume fraction and permits one to represent and evaluate certain n-point correlation functions that statistically characterize the microstructure for this model. Unlike the case of statistically homogeneous media, the microstructure functions depend upon the absolute positions of their arguments. However, as with homogeneous random media, this microstructural information will be useful in obtaining rigorous estimates of the effective properties of such systems. Typeset using REVT E X I. INTRODUCTION Much progress has been made in recent years in characterizing the microstructure of statistically homogeneous two-phase random media via a variety of n-point correlation functions [1--3]. For ergodic ensembles, the n-point correlation func...