118695268
Evidence for anti-muon-neutrino ---> anti-electron-neutrino oscillations from the LSND experiment at LAMPF
A search for $\bar\nu_{\mu}\to \bar\nu_{e}$ oscillations has been conducted at the Los Alamos Meson Physics Facility by using $\bar\nu_\mu$ from $\mu^+$ decay at rest. The $\bar\nu_e$ are detected via the reaction $\bar\nu_e\,p \rightarrow e^{+}\,n$, correlated with a $\gamma$ from $np\rightarrow d\gamma$ ($2.2\,{\rm MeV}$). The use of tight cuts to identify $e^+$ events with correlated $\gamma$ rays yields 22 events with $e^+$ energy between 36 and $60\,{\rm MeV}$ and only $4.6 \pm 0.6$ background events. A fit to the $e^+$ events between 20 and $60\,{\rm MeV}$ yields a total excess of $51.8^{+18.7}_{-16.9} \pm 8.0$ events. If attributed to $\bar \nu_\mu \rightarrow \bar \nu_e$ oscillations, this corresponds to an oscillation probability of ($0.31^{+0.11}_{-0.10} \pm 0.05$)\%.
140089864
Critical current, electro-mechanical properties and specific heat of bronze Nb-3_Sn conductors
123029043
Evidence of soft and collinear gluon emission ine+e− hadronic events
In the study of rapidity distributions of charged pions produced ine+e− annihilation at 29 GeV, we observe a significant dip in the rapidity distributions aty≈0 for events with low sphericity. A comparison of data with several QCD-based phenomenological models strongly suggests that this structure is related to the emission of multiple soft and/or collinear gluons.
120548922
EXPERIMENTAL LIMITS ON THE PRODUCTION OF EXCITED LEPTONS AND STABLE HEAVY-LEPTONS
The results are reported of a search for excited muons (..mu..*) and electrons (e*) and for a stable charged heavy lepton by measurements of the e/sup +/e/sup -/..--> mu../sup +/..mu../sup -/, ..mu../sup +/..mu../sup -/..gamma.., ..mu../sup +/..mu../sup -/..gamma gamma.., and ..gamma gamma.. final states. Excluded are large regions of the lambda (coupling constant), M (mass) planes for spin-(1/2) ..mu..* and e*, and a new stable charged heavy lepton with mass<14 GeV.
125293645
EXPERIMENTAL STUDY OF HEAVY CHARGED LEPTONS AT PETRA
18317704
Measurement of Tau branching ratios
Using the data accumulated at LEP in 1989 and 1990 with the ALEPH detector, the inclusive and exclusive branching ratios of the τ lepton have been measured assuming lepton universality inZ0 decays. The inclusive branching fractions for the τ decay into one, three, and five charged particles have been determined to be (85.45±0.97)%, (14.35±0.48)%, and (0.10±0.05)%, respectively, in agreement with the world averages. New undetected decay modes are determined to have a branching fraction of less than 2.1% at 95% CL. The measured branching ratios for quasi-exclusive channels are slightly larger than, but consistent with the world averages, except for the modes τ→3 hadrons+vτ andτ→hadron+2π0vτ, which are significantly larger. These latter branching ratios have been found to be (9.5±0.7)% and (10.2±1.1)%, respectively. The sum of all the measured quasi-exclusive branching ratios is (100.4±1.8)%. A fully exclusive analysis of modes with neutral pions shows no evidence for new photonic decay modes with a branching fraction limit of 3.4% at 95% CL.
6120041
N-body simulations for testing the stability of triaxial galaxies in MOND
We perform a stability test of triaxial models in Modified Newtonian Dynamics (MOND) using N-body simulations. The triaxial models considered here have densities that vary with r −1 in the centre and r −4 at large radii. The total mass of the model varies from 10 8 to 10 10 M� , representing the mass scale of dwarfs to medium-mass elliptical galaxies, respectively, from deep MOND to quasi-Newtonian gravity. We build triaxial galaxy models using the Schwarzschild technique, and evolve the systems for 200 Keplerian dynamical times (at the typical length-scale of 1.0 kpc). We find that the systems are virial overheating, and in quasi-equilibrium with the relaxation taking approximately 5 Keplerian dynamical times (1.0 kpc). For all systems, the change of the inertial (kinetic) energy is less than 10 per cent (20 per cent) after relaxation. However, the central profile of the model is flattened during the relaxation and the (overall) axis ratios change by roughly 10 per cent within 200 Keplerian dynamical times (at 1.0 kpc) in our simulations. We further find that the systems are stable once they reach the equilibrium state.
119206435
Search for the weak decays $J/\psi \to D^{(*)}_{s}e\nu_{e}$
Using a sample of $2.25\times 10^8$ $J/\psi$ events collected with the BESIII detector at the BEPCII collider, we search for the $J/\psi$ semi-leptonic weak decay $J/\psi \to D^{-}_{s} e^{+}\nu_{e}+c.c.$ with a much higher sensitivity than previous searches. We also perform the first search for $J/\psi \to D^{*-}_{s} e^{+}\nu_{e}+c.c.$ No significant excess of a signal above background is observed in either channel. At the $90\%$ confidence level, the upper limits are determined to be $\mathcal{B}(J/\psi \to D^{-}_{s}e^{+}\nu_{e}+c.c.)<1.3\times10^{-6}$ and $\mathcal{B}(J/\psi \to {D^{*}_{s}}^{-}e^{+}\nu_{e}+c.c.)<1.8\times10^{-6}$, respectively. Both are consistent with Standard Model predictions.
54686029
Dynamic polarization effects in ion channeling through single-wall carbon nanotubes
Ion channeling through a single-wall carbon nanotube is simulated by solving Newton’s equations for ion motion at intermediate energies, under the action of both the surface-atom repulsive forces and the polarization forces due to the dynamic perturbation of the nanotube electrons. The atomic repulsion is described by a continuum potential based on the Thomas-Fermi-Moliere model, whereas the dynamic polarization of the nanotube electrons is described by a two-dimensional hydrodynamic model, giving rise to the transverse dynamic image force and the longitudinal stopping force. In the absence of centrifugal forces, a balance between the image force and the atomic repulsion is found to give rise to ion trajectories which oscillate over peripheral radial regions in the nanotube, provided the ion impact position is not too close to the nanotube wall, the impact angle is sufficiently small, and the incident speed is not too high. Otherwise, the ion is found to oscillate between the nanotube walls, passing over a local maximum of the potential in the center of the nanotube, which results from the image interaction. The full statistical analysis of 10 3 ion trajectories has been made to further demonstrate the actual effect of dynamic polarization on the ion channeling.
3614734
The Secondary infall model of galactic halo formation and the spectrum of cold dark matter particles on earth
The spectrum of cold dark matter particles on Earth is expected to have peaks in velocity space associated with particles which are falling onto the Galaxy for the first time and with particles which have fallen in and out of the Galaxy only a small number of times in the past. We obtain estimates for the velocity magnitudes and the local densities of the particles in these peaks. To this end we use the secondary infall model of galactic halo formation which we have generalized to take account of the angular momentum of the dark matter particles. The new model is still spherically symmetric and it admits self-similar solutions. In the absence of angular momentum, the model produces flat rotation curves for a large range of values of a parameter \ensuremath{\epsilon} which is related to the spectrum of primordial density perturbations. We find that the presence of angular momentum produces an effective core radius; i.e., it makes the contribution of the halo to the rotation curve go to zero at zero radius. The model provides a detailed description of the large scale properties of galactic halos including their density profiles, their extent, and total mass. We obtain predictions for the kinetic energies of the particles in the velocity peaks and estimates for their local densities as functions of the amount of angular momentum, the age of the Universe, and \ensuremath{\epsilon}.
42340868
New limits on the ultrahigh energy cosmic neutrino flux from the ANITA experiment.
We report initial results of the first flight of the Antarctic Impulsive Transient Antenna (ANITA-1) 2006-2007 Long Duration Balloon flight, which searched for evidence of a diffuse flux of cosmic neutrinos above energies of E(nu) approximately 3 x 10(18) eV. ANITA-1 flew for 35 days looking for radio impulses due to the Askaryan effect in neutrino-induced electromagnetic showers within the Antarctic ice sheets. We report here on our initial analysis, which was performed as a blind search of the data. No neutrino candidates are seen, with no detected physics background. We set model-independent limits based on this result. Upper limits derived from our analysis rule out the highest cosmogenic neutrino models. In a background horizontal-polarization channel, we also detect six events consistent with radio impulses from ultrahigh energy extensive air showers.