5,568 research outputs found
The Status of MSSM Higgs Boson Searches at LEP
The most recently available results from searches conducted by the four LEP
experiments at 189 GeV center-of-mass energy for Higgs bosons of the Minimal
Supersymmetric Standard Model (MSSM) are presented. No evidence for a signal
has been observed, and the null result is used by the experiments, both
individually and collectively, to exclude regions of the MSSM parameter space
and to set lower limits on Higgs boson masses at 95% confidence level in
constrained MSSM scenarios.Comment: 7 pages, 6 figures, REVTeX, to appear in the proceedings of the DPF
'99 conference, 5-9 January 1999, Los Angeles, C
New Results on the Hadronic Contributions to alpha(M_Z) and to (g-2)_mu
We reevaluate the dispersion integrals of the leading order hadronic
contributions to the running of the QED fine structure constant alpha(s) at
s=M_Z^2, and to the anomalous magnetic moments of the muon and the electron.
Finite-energy QCD sum rule techniques complete the data from e+e- annihilation
and tau decays at low energy and at the cc-bar threshold. Global quark-hadron
duality is assumed in order to resolve the integrals using the Operator Product
Expansion wherever it is applicable.
We obtain delta_alpha_had(M_Z) = (276.3 +/- 1.6)x10^{-4} yielding
alpha^{-1}(M_Z) = 128.933 +/- 0.021, and a_mu^had = (692.4 +/- 6.2)x10^{-10}
with which we find for the complete Standard Model prediction a_mu^SM =
(11659159.6 +/- 6.7)x10^{-10}. For the electron, the hadronic contribution
reads a_e^had = (187.5 +/- 1.8)x10^{-14}.Comment: 16 pages, 3 figure
Updated Estimate of the Muon Magnetic Moment Using Revised Results from e+e- Annihilation
A new evaluation of the hadronic vacuum polarization contribution to the muon
magnetic moment is presented. We take into account the reanalysis of the
low-energy e+e- annihilation cross section into hadrons by the CMD-2
Collaboration. The agreement between e+e- and tau spectral functions in the pi
pi channel is found to be much improved. Nevertheless, significant
discrepancies remain in the center-of-mass energy range between 0.85 and 1.0
GeV, so that we refrain from averaging the two data sets. The values found for
the lowest-order hadronic vacuum polarization contributions are a_mu[had,LO] =
(696.3 +- 6.2[exp] +- 3.6[rad])e-10 (e+e- -based) and a_mu[had,LO] = (711.0 +-
5.0[exp] +- 0.8[rad] +- 2.8[SU2])e-10 (tau-based), where the errors have been
separated according to their sources: experimental, missing radiative
corrections in e+e- data, and isospin breaking. The corresponding Standard
Model predictions for the muon magnetic anomaly read a_mu = (11,659,180.9 +-
7.2[had] +- 3.5[LBL] +- 0.4[QED+EW])e-10 (e+e- -based) and a_mu = (11,659,195.6
+- 5.8[had] +- 3.5[LBL] +- 0.4[QED+EW])e-10 (tau-based), where the errors
account for the hadronic, light-by-light (LBL) scattering and electroweak
contributions. The deviations from the measurement at BNL are found to be (22.1
+- 7.2 +- 3.5 +- 8.0)e-10 (1.9 sigma) and (7.4 +- 5.8 +- 3.5 +- 8.0)e-10 (0.7
sigma) for the e+e- and tau-based estimates, respectively, where the second
error is from the LBL contribution and the third one from the BNL measurement.Comment: 14 pages, 7 figures (to be submitted to Phys Lett B
CAMIEM: Compact Additively Manufactured Innovative Electric Motor
New manufacturing methods are needed to obtain innovative electric motor designs that have much higher power densities and/or efficiencies compared to the current state-of-the-art. Additive manufacturing offers the potential to radically change motor designs so that they have compact designs, multi-material components, innovative cooling, and optimally designed and manufactured components. New component designs enabled by additive manufacturing technologies have been designed and were fabricated to include the housing, rotors, stator cooling ring, a direct printed stator, and a wire embedded stator. The new components were integrated into the motor and tested evaluate the performance gains in comparison to the baseline electric motor configuration. Partners on the sub-project include NASA GRC, NASA LaRC, NASA AFRC, LaunchPoint Technologies, and the University of Texas El Paso
Two-dimensional oscillating airfoil test apparatus
A two dimensional oscillating airfoil test apparatus is presented as a method of measuring unsteady aerodynamic forces on an airfoil or rotor blade section. The oscillating airfoil test rig, which is being built for use in an 11 X 11-foot transonic wind tunnel (speed range M = 0.4 - 1.4), will allow determination of unsteady loadings and detailed pressure distributions on representative airfoil sections undergoing simulated pitching and flapping motions. The design details of the motion generating system and supporting structure are presented. This apparatus is now in the construction phase
Strange Quark Mass from the Invariant Mass Distribution of Cabibbo-Suppressed Tau Decays
Quark mass corrections to the tau hadronic width play a significant role only
for the strange quark, hence providing a method for determining its mass. The
experimental input is the vector plus axial-vector strange spectral function
derived from a complete study of tau decays into strange hadronic final states
performed by ALEPH. New results on strange decay modes from other experiments
are also incorporated. The present analysis determines the strange quark mass
at the Mtau mass scale using moments of the spectral function. Justified
theoretical constraints are applied to the nonperturbative components and
careful attention is paid to the treatment of the perturbative expansions of
the moments which exhibit convergence problems. The result obtained,
m_s(Mtau^2) = (120 +- 11_exp +- 8_Vus +- 19_th) MeV = (120^+21_-26) MeV, is
stable over the scale from Mtau down to about 1.4 GeV. Evolving this result to
customary scales yields m_s(1 GeV^2) = (160^+28_-35) MeV and m_s(4 GeV^2) =
(116^+20_-25) MeV.Comment: LaTex, 8 pages, 4 figures (EPS
Receptor tyrosine kinase expression and phosphorylation in canine nasal carcinoma
Master of Science in Biomedical SciencesDepartment of Clinical SciencesMary Lynn HigginbothamThis study evaluated sixteen canine nasal carcinoma and five normal nasal epithelium samples for expression and phosphorylation of known targets of toceranib [vascular endothelial growth factor receptor-2 (VEGR2), platelet derived growth factor alpha (PDGFR-[alpha]), platelet derived growth factor receptor beta (PDGFR-[beta]), and stem cell factor receptor (c-KIT)] and epidermal growth factor receptor 1 (EGFR1) using immunohistochemistry, RT-PCR and a receptor tyrosine kinase (RTK) phosphorylation panel. Protein for VEGFR2 was expressed in neoplastic cells of all carcinomas, PDGFR-[alpha] was noted in 15/16, whereas PDGFR-[beta] was detected in 3/16 samples, but showed primarily stromal staining. Protein expression for c-KIT was present in 4/16 and EGFR1 was noted in 14/16 samples. Normal tissue showed variable protein expression of the RTKs. Messenger RNA for VEGFR2, PDGFR-[beta], and c-KIT were noted in all samples. Messenger RNA for PDGFR-[alpha] and EGFR1 were detected in 15/16 samples. All normal nasal tissue detected messenger RNA for all RTKs of interest. Constitutive phosphorylation of VEGFR2, PDGFR-[alpha], PDGFR-[beta] and c-KIT was not observed in any carcinoma or normal nasal sample, but phosphorylation of EGFR1 was noted in 10/16 carcinoma and 3/5 normal samples. The absence of major phosphorylated RTK targets of toceranib suggests the clinical effect of toceranib may occur through inhibition of alternative and currently unidentified RTK pathways in canine nasal carcinomas. The observed protein and message expression and phosphorylation of EGFR1 in the nasal carcinoma samples merits further inquiry into EGFR1 as a therapeutic target for this cancer
Testing the dynamics of B -> \pi\pi and constraints on \alpha
In charmless nonleptonic B decays to \pi\pi or \rho\rho, the "color allowed"
and "color suppressed" tree amplitudes can be studied in a systematic expansion
in \alphas(mb) and \Lambda/mb. At leading order in this expansion their
relative strong phase vanishes. The implications of this prediction are
obscured by penguin contributions. We propose to use this prediction to test
the relative importance of the various penguin amplitudes using experimental
data. The present B->\pi\pi data suggest that there are large corrections to
the heavy quark limit, which can be due to power corrections to the tree
amplitudes, large up-quark penguin amplitude, or enhanced weak annihilation.
Because the penguin contributions are smaller, the heavy quark limit is more
consistent with the B->\rho\rho data, and its implications may become important
for the extraction of \alpha from this mode in the future.Comment: 8 pages, 6 figures, includes special style file; final version to
appear in Phys. Rev.
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