60,013 research outputs found

### SU(3) Flavor Breaking in Hadronic Matrix Elements for $B - \bar B$ Oscillations

We present an analysis, using quenched configurations at $6/g^2=$5.7, 5.85,
6.0, and 6.3 of the matrix element \MP\equiv\langle \bar P_{hl}|\bar h
\gamma_\mu (1-\gamma_5)l \bar h \gamma_\mu(1-\gamma_5)l|P_{hl}\rangle for
heavy-light pseudoscalar mesons. The results are extrapolated to the physical
$B$ meson states, \Bd and \Bs. We directly compute the ratio \MS/\MB, and
obtain the preliminary result \MS/\MB=1.54(13)(32). A precise value of this
SU(3) breaking ratio is important for determining $V_{td}$ once the mixing
parameter $x_s$ for \Bs-\bar\Bs is measured experimentally. We also determine
values for the corresponding B parameters, $B_{bs}(2 \rm{GeV})=B_{bd}(2
\rm{GeV})=1.02(13)$, which we cannot distinguish in the present analysis.Comment: Poster presented at LATTICE96(heavy quarks). LaTeX, uses espcrc2.sty
and epsf, 4 pages, 4 postscript figures include

### A Nonlinear Least Squares Fit procedure for analysis of immittance data of electrochemical systems

A Nonlinear Least Squares Fit (NLLSF) program is described, with which frequency dispersion data of electrochemical systems can be analyzed in terms of an equivalent circuit. The NLLSF procedure uses a combination of an analytical and gradient search according to the Marquardt algorithm. Through the use of an unique Circuit Description Code (CDC) different equivalent circuits may be used with the program. The use of an analytical derivatives routine enhances the execution speed. The power of such a fit procedure is demonstrated in multi parameter fits, on synthetic and real data, performed by the program “EQIVCT”

### A package for impedance/admittance data analysis

An outline is given of a Basic computer program which facilitates the analysis of frequency dispersion data. With this program an equivalent circuit, and starting values for the corresponding circuit parameters, can be extracted from the dispersion data. A circuit description together with crude parameter values form an essential requirement for a subsequent NLLSF procedure. A brief description is given of a frequency dispersion simulation program, also written in Basic, which can be used to compare measured data with a calculated response. Both programs employ the Circuit Description Code (CDC), thus allowing the use of a variety of equivalent circuits. The use of both programs is demonstrated with the analysis of a dispersion measurement performed on a sample of Sn-doped AgCrS2, which is a pure ionic conductor

### Threshold Two-Pion Photo- and Electroproduction: More neutrals than expected

We present an exploratory study of two pion photo-- and electroproduction off
the nucleon in the threshold region. To calculate the pertinent amplitudes, we
make use of heavy baryon chiral perturbation theory. We show that due to finite
chiral loops the production cross section for final states with two neutral
pions is considerably enhanced. The experimental implications are briefly
discussed.Comment: 23pp, plain TeX, 11 figures available upon request, CRN 94/1

### Staggered Chiral Perturbation Theory for Heavy-Light Mesons

We incorporate heavy-light mesons into staggered chiral perturbation theory,
working to leading order in 1/m_Q, where m_Q is the heavy quark mass. At first
non-trivial order in the chiral expansion, staggered taste violations affect
the chiral logarithms for heavy-light quantities only through the light meson
propagators in loops. There are also new analytic contributions coming from
additional terms in the Lagrangian involving heavy-light and light mesons.
Using this heavy-light staggered chiral perturbation theory, we perform the
one-loop calculation of the B (or D) meson leptonic decay constant in the
partially quenched and full QCD cases. In our treatment, we assume the validity
both of the "fourth root trick" to reduce four staggered tastes to one, and of
the prescription to represent this trick in the chiral theory by insertions of
factors of 1/4 for each sea quark loop.Comment: 48 pages, 6 figures. v3: Some clarifying comments/caveats added;
typos fixed. Corresponds to published versio

### The GRADIO spaceborne gravity gradiometer: Development and accommodation

The European ARISTOTELES mission aims at the determination of the Earth's gravity field at short wavelength with a global coverage. Gravity gradient measurements will be achieved during six months by the GRADIO instrument onboard a dedicated satellite in a near dawn-dusk sun-synchronous orbit at an altitude of 200 km. The objective is an accuracy of better than 5 mgals for gravity anomalies, at ground level for blocks of 1 x 1 deg. According to present knowledge of the potential, the recovery of higher spherical harmonics (degree and order greater than 30) is of main importance. This leads to focus on the variations of the measured components T(sub ij) of the gravity gradient tensor, at frequencies greater than 5 x 10(exp -3) Hz. The resolution, required for the gradiometer is 10(exp -2) Eotvos (i.e., 10(exp -11)/s squared) with an averaging time of 4 s

### Errata for: Differential Equations for Sine-Gordon Correlation Functions at the Free Fermion Point

We present some important corrections to our work which appeared in Nucl.
Phys. B426 (1994) 534 (hep-th/9402144). Our previous results for the
correlation functions $\langle e^{i\alpha \Phi(x)} e^{i\alpha' \Phi (0) }
\rangle$ were only valid for $\alpha = \alpha'$, due to the fact that we didn't
find the most general solution to the differential equations we derived. Here
we present the solution corresponding to $\alpha \neq \alpha'$.Comment: 4 page

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