8,900 research outputs found
Measurements of Absolute Hadronic Branching Fractions of D Mesons
Using e+e- collisions recorded at the psi(3770) resonance with the CLEO-c
detector at the Cornell Electron Storage Ring, we determine absolute hadronic
branching fractions of charged and neutral D mesons. Among measurements for
both Cabibbo-favored and Cabibbo-suppressed modes, we obtain reference
branching fractions B(D0 -> K-pi+)=(3.91 +- 0.08 +- 0.09)% and B(D+ ->
K-pi+pi+)=(9.5 +- 0.2 +- 0.3)%, where the uncertainties are statistical and
systematic, respectively. Using a determination of the integrated luminosity,
we also extract the e+e- -> DDbar cross sections.Comment: 3 pages, to appear in the Proceedings of PANIC'05 (Particles and
Nuclei International Conference), Santa Fe, NM, October 24-28 200
Simultaneous Least Squares Treatment of Statistical and Systematic Uncertainties
We present a least squares method for estimating parameters from measurements
of event yields in the presence of background and crossfeed. We adopt a unified
approach to incorporating the statistical and systematic uncertainties on the
experimental measurements input to the fit. We demonstrate this method with a
fit for absolute hadronic D meson branching fractions, measured in e+e- ->
\psi(3770) -> D\bar D$ transitions.Comment: 9 pages, 2 figures; minor clarifications, one figure adde
Factoring the unitary evolution operator and quantifying entanglement
The unitary evolution can be represented by a finite product of exponential
operators. It leads to a perturbative expression of the density operator of a
close system. Based on the perturbative expression scheme, we present a
entanglement measure, this measure has the advantage that it is easy to compute
for a general dynamical process.Comment: 11 pages, LATEX, no figure
D0D0bar Quantum Correlations, Mixing, and Strong Phases
Due to the presence of the quantum correlation between the pair-produced D0
and D0bar from the decay of the psi(3770), the time-integrated single and
double tag decay rates depend on charm mixing amplitudes,
doubly-Cabibbo-suppressed amplitudes, and the relative strong phase, delta,
between D0 and D0bar decays to identical final states. Using 281 pb^-1 of
integrated luminosity collected with the CLEO-c detector on the psi(3770)
resonance, we measure the absolute branching fractions of D0 decays to K-pi+,
CP eigenstates, and semileptonic final states to determine cos(delta) for K-pi+
and to limit the mixing amplitude y.Comment: 3 pages, to appear in the Proceedings of PANIC'05 (Particles and
Nuclei International Conference), Santa Fe, NM, October 24-28 200
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Fast response time fiber optical pH and oxygen sensors
While fluorescence-based fiber optic sensors for measuring both pH and oxygen concentration (O2) are well known, current sensors are often limited by their response time and drift, which limits the use of existing fiber optic sensors of this type in wider applications, for example in physiology and other fields. Several new fiber optical sensors have been developed and optimized, with respect to key features such as tip shape and coating layer thickness. In this work, preliminary results on the performance of a suite of pH sensors with fast response times, < 3 second and oxygen sensors (O2) with response times < 0.2 second. The sensors have been calibrated and their performance analyzed using the Henderson–Hasselbalch equation (pH) and classic Lehrer-model (O2)
Microscopic Description of Band Structure at Very Extended Shapes in the A ~ 110 Mass Region
Recent experiments have confirmed the existence of rotational bands in the A
\~ 110 mass region with very extended shapes lying between super- and
hyper-deformation. Using the projected shell model, we make a first attempt to
describe quantitatively such a band structure in 108Cd. Excellent agreement is
achieved in the dynamic moment of inertia J(2) calculation. This allows us to
suggest the spin values for the energy levels, which are experimentally
unknown. It is found that at this large deformation, the sharply down-sloping
orbitals in the proton i_{13/2} subshell are responsible for the irregularity
in the experimental J(2), and the wave functions of the observed states have a
dominant component of two-quasiparticles from these orbitals. Measurement of
transition quadrupole moments and g-factors will test these findings, and thus
can provide a deeper understanding of the band structure at very extended
shapes.Comment: 4 pages, 3 eps figures, final version accepted by Phys. Rev. C as a
Rapid Communicatio
Bell Inequalities Classifying Bi-separable Three-qubit States
We present a set of Bell inequalities that gives rise to a finer
classification of the entanglement for tripartite systems. These inequalities
distinguish three possible bi-separable entanglements for three-qubit states.
The three Bell operators we employed constitute an external sphere of the
separable cube.Comment: 8 page
The X-ray coronae of the two brightest galaxies in the Coma cluster
We use deep Chandra X-ray Observatory observations to examine the coronae of
the two brightest cluster galaxies in the Coma cluster of galaxies, NGC 4874
and NGC 4889. We find that NGC 4889 hosts a central depression in X-ray surface
brightness consistent with a cavity or pair of cavities of radius 0.6 kpc. If
the central cavity is associated with an AGN outburst and contains relativistic
material, its enthalpy should be around 5x10^55 erg. The implied heating power
of this cavity would be around an order of magnitude larger than the energy
lost by X-ray emission. It would be the smallest and youngest known cavity in a
brightest cluster galaxy and the lack of over pressuring implies heating is
still gentle. In contrast, NGC 4874 does not show any evidence for cavities,
although it hosts a well-known wide-angle-tail radio source which is visible
outside the region occupied by the X-ray corona. These two galaxies show that
AGN feedback can behave in varied ways in the same cluster environment.Comment: 11 pages, 11 figures, accepted by MNRA
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