22,409 research outputs found
CP violating dimuon charge asymmetry in general left-right models
The recently measured charge asymmetry of like-sign dimuon events by the D0
collaboration at Tevatron shows the 3.9 \sigma\ deviation from the standard
model prediction. In order to solve this mismatch, we investigate the
right-handed current contributions to and
mixings which are the major source of the like-sign dimuon events in production in general left-right models without imposing manifest or
pseudo-manifest left-right symmetry. We find the allowed region of new physics
parameters satisfying the current experimental data.Comment: 9 pages, 4 figure
State space collapse and diffusion approximation for a network operating under a fair bandwidth sharing policy
We consider a connection-level model of Internet congestion control,
introduced by Massouli\'{e} and Roberts [Telecommunication Systems 15 (2000)
185--201], that represents the randomly varying number of flows present in a
network. Here, bandwidth is shared fairly among elastic document transfers
according to a weighted -fair bandwidth sharing policy introduced by Mo
and Walrand [IEEE/ACM Transactions on Networking 8 (2000) 556--567] []. Assuming Poisson arrivals and exponentially distributed document
sizes, we focus on the heavy traffic regime in which the average load placed on
each resource is approximately equal to its capacity. A fluid model (or
functional law of large numbers approximation) for this stochastic model was
derived and analyzed in a prior work [Ann. Appl. Probab. 14 (2004) 1055--1083]
by two of the authors. Here, we use the long-time behavior of the solutions of
the fluid model established in that paper to derive a property called
multiplicative state space collapse, which, loosely speaking, shows that in
diffusion scale, the flow count process for the stochastic model can be
approximately recovered as a continuous lifting of the workload process.Comment: Published in at http://dx.doi.org/10.1214/08-AAP591 the Annals of
Applied Probability (http://www.imstat.org/aap/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Solid particle erosion of environmental barrier coatings and ceramic matrix composites
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Article Including Environmental Barrier Coating System
An enhanced environmental barrier coating for a silicon containing substrate. The enhanced barrier coating may include a bond coat doped with at least one of an alkali metal oxide and an alkali earth metal oxide. The enhanced barrier coating may include a composite mullite bond coat including BSAS and another distinct second phase oxide applied over said surface
Modulation of the Curie Temperature in Ferromagnetic/Ferroelectric Hybrid Double Quantum Wells
We propose a ferromagnetic/ferroelectric hybrid double quantum well
structure, and present an investigation of the Curie temperature (Tc)
modulation in this quantum structure. The combined effects of applied electric
fields and spontaneous electric polarization are considered for a system that
consists of a Mn \delta-doped well, a barrier, and a p-type ferroelectric well.
We calculate the change in the envelope functions of carriers at the lowest
energy sub-band, resulting from applied electric fields and switching the
dipole polarization. By reversing the depolarizing field, we can achieve two
different ferromagnetic transition temperatures of the ferromagnetic quantum
well in a fixed applied electric field. The Curie temperature strongly depends
on the position of the Mn \delta-doped layer and the polarization strength of
the ferroelectric well.Comment: 9 pages, 5 figures, to be published in Phys. Rev. B (2006) minor
revision: One of the line types is changed in Fig.
Flux Noise in MgB2 Thin Films
We have performed flux noise and AC-susceptibility measurements on two 400 nm
thick MgB films. Both measurement techniques give information about the
vortex dynamics in the sample, and hence the superconducting transition, and
can be linked to each other through the fluctuation-dissipation-theorem. The
transition widths for the two films are 0.3 and 0.8 K, respectively, and the
transitions show a multi step-like behavior in the AC-susceptibility
measurements. The same phenomenon is observed in the flux noise measurements
through a change in the frequency dependence of the spectral density at each
step in the transition. The results are discussed and interpreted in terms of
vortices carrying an arbitrary fraction of a flux quantum as well as in terms
of different macroscopic regions in the films having slightly different
compositions, and hence, different critical temperatures.Comment: 8 pages, 4 figures, conference contribution to "Fluctuations and
Noise", Santa Fe, New mexico 1-4 june 200
Multilayer article having stabilized zirconia outer layer and chemical barrier layer
A multilayer article includes a substrate that includes at least one of a ceramic compound and a Si-containing metal alloy. An outer layer includes stabilized zirconia. Intermediate layers are located between the outer layer and the substrate and include a mullite-containing layer and a chemical barrier layer. The mullite-containing layer includes 1) mullite or 2) mullite and an alkaline earth metal aluminosilicate. The chemical barrier layer is located between the mullite-containing layer and the outer layer. The chemical barrier layer includes at least one of mullite, hafnia, hafnium silicate and rare earth silicate (e.g., at least one of RE.sub.2 SiO.sub.5 and RE.sub.2 Si.sub.2 O.sub.7 where RE is Sc or Yb). The multilayer article is characterized by the combination of the chemical barrier layer and by its lack of a layer consisting essentially of barium strontium aluminosilicate between the mullite-containing layer and the chemical barrier layer. Such a barium strontium aluminosilicate layer may undesirably lead to the formation of a low melting glass or unnecessarily increase the layer thickness with concomitant reduced durability of the multilayer article. In particular, the chemical barrier layer may include at least one of hafnia, hafnium silicate and rare earth silicate
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