8,960 research outputs found
B-Physics Observables and Electroweak Precision Data in the CMSSM, mGMSB and mAMSB
We explore electroweak precision observables (EWPO) and -physics
observables (BPO) in the CMSSM, the mGMSB and the mAMSB. We perform a chi^2
analysis based on the combination of current EWPO and BPO data. For the first
time this allows the comparison of the mGMSB and mAMSB in terms of EWPO and BPO
with the CMSSM. We find that relatively low mass scales in all three scenarios
are favored. However, the current data from EWPO and BPO can hardly exclude any
parameters at the level of Delta chi^2 = 9. Remarkably the mAMSB scenario,
despite having one free GUT scale parameter less than the other two scenarios,
has a somewhat lower total minimum chi^2. We present predictions for the
lightest Higgs boson mass, based on the chi^2 analysis of current data, where
relatively good compatibility with the bounds from Higgs searches at LEP is
found. We also present the predictions for other Higgs sector parameters and
SUSY mass scales, allowing to compare the reach of the LHC and the ILC in the
three scenarios. We furthermore explore the future sensitivities of the EWPO
and BPO for the current best-fit results and for a hypothetical point with
somewhat higher mass scales that results in a similar Higgs and SUSY spectrum
in the three scenarios. We find that the future improvement of the accuracy of
the EWPO and BPO will lead to a significant gain in the indirect parameter
determination. The improvement is similar in the CMSSM, mGMSB and mAMSB and
will yield constraints to the parameter space even for heavy Higgs and SUSY
mass scales.Comment: 53 pages, 27 figures, discussion extended. Version to appear in JHE
Activation of additional energy dissipation processes in the magnetization dynamics of epitaxial chromium dioxide films
The precessional magnetization dynamics of a chromium dioxide film is
examined in an all-optical pump-probe setup. The frequency dependence on the
external field is used to extract the uniaxial in-plane anisotropy constant.
The damping shows a strong dependence on the frequency, but also on the laser
pump fluency, which is revealed as an important experiment parameter in this
work: above a certain threshold further channels of energy dissipation open and
the damping increases discontinuously. This behavior might stem from spin-wave
instabilities
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Microwave-Induced Interfacial Nanobubbles
A new method for generating nanobubbles via microwave irradiation was verified and quantified. AFM measurement showed that nanobubbles with diameters ranging in 200 - 600 nm were generated at water-HOPG surface by applying microwave to aqueous solutions with 9.0 - 30.0 mg/L of dissolved oxygen. Graphite displays strong microwave absorption and transmits high thermal energy to surface. Due to high dielectric constant (20 °C, 80 F/m) and dielectric loss factor, water molecule has strong absorption ability for microwave. The thermal and non-thermal effects of microwave both had contributions to decrease gas solubility and that facilitated nanobubble nucleation. The yield of nanobubbles increased about ten times when irradiation time increased from 60 s to 120 s at 200 W microwave. The nanobubbles density increased from 0.8 to 15 numbers/μm2 by improving working power from 200 to 600 W. An apparent improvement of nanobubbles yield was obtained between 300 and 400 W, and the resulting temperature was 34 - 52 °C. When the initial dissolved oxygen increased from 11.3 to 30.0 mg/L, the density of nanobubbles increased from 1.2 to 13 numbers/μm2. The generation of nanobubbles could be well controlled by adjusting gas concentration, microwave power or irradiation time. The method maybe valuable in preparing surface nanobubbles quickly and conveniently for various applications, such as catalysis, hypoxia/anoxia remediation or as templates to prepare nanoscale materials
Enhanced spin-orbit torques in MnAl/Ta films with improving chemical ordering
We report the enhancement of spin-orbit torques in MnAl/Ta films with
improving chemical ordering through annealing. The switching current density is
increased due to enhanced saturation magnetization MS and effective anisotropy
field HK after annealing. Both damplinglike effective field HD and fieldlike
effective field HF have been increased in the temperature range of 50 to 300 K.
HD varies inversely with MS in both of the films, while the HF becomes liner
dependent on 1/MS in the annealed film. We infer that the improved chemical
ordering has enhanced the interfacial spin transparency and the transmitting of
the spin current in MnAl layer
Imaging atom-clusters by hard x-ray free electron lasers
The ingenious idea of single molecule imaging by hard x-ray Free Electron
Laser (X-FEL) pulses was recently proposed by Neutze et al.
[Nature,406,752(2000)]. However, in their numerical modelling of the Coulomb
explosion several interactions were neglected and no reconstruction of the
atomic structure was given. In this work we carried out improved molecular
dynamics calculations including all quantum processes which affect the
explosion. Based on this time evolution we generated composite elastic
scattering patterns, and by using Fienup's algorithm successfully reconstructed
the original atomic structure. The critical evaluation of these results gives
guidelines and sets important conditions for future experiments aiming single
molecule structure solution.Comment: 8 pages, 4 figures, submitted to Europhysics Letter
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