3,178 research outputs found
Ultra Fast Nonlinear Optical Tuning of Photonic Crystal Cavities
We demonstrate fast (up to 20 GHz), low power (5 ) modulation of
photonic crystal (PC) cavities in GaAs containing InAs quantum dots. Rapid
modulation through blue-shifting of the cavity resonance is achieved via free
carrier injection by an above-band picosecond laser pulse. Slow tuning by
several linewidths due to laser-induced heating is also demonstrated
W mass and Triple Gauge Couplings at Tevatron
On behalf of CDF and D0 CollaborationsInternational audienceThe W mass is a crucial parameter in the Standard Model (SM) of particle physics, providing constraints on the mass of the Higgs boson as well as on new physics models via quantum loop corrections. On the other hand, any deviation of the triple gauge boson couplings (TGC) from their values predicted by the SM would be also an indication for new physics. We present recent measurements on W boson mass and searches for anomalous TGC (aTGC) in Wγ, Zγ, WW, WZ and ZZ at Fermilab Tevatron both by CDF and DØ Collaborations. The CDF Collaboration has measured the W boson mass using data corresponding to 2.2 fb−1 of integrated luminosity. The measurement, performed using electron and muon decays of W boson, yields a mass of MW = 80387 ± 19 MeV. The DØ Collaboration has measured MW = 80367 ± 26 MeV with data corresponding to 4.3 fb−1 of integrated luminosity in the channel W → ev. The combination with an earlier DØ result, using independant data sample at 1 fb−1 of integrated luminosity, yields MW = 80375 ± 23 MeV. The limits on anomalous TGCs parameters are consistent with the SM expectations
W and Z physics at TeVatron
14 pages, XXV Physics in Collision "PIC05", Prague, July 06-09 2005, On behalf of the CDF and D0 Collaborations - On behalf of the CDF and D0 CollaborationsElectroweak measurements performed by CDF and D0 are reported, corresponding to data collected at the centre-of-mass energy of 1.96 TeV with approximately a luminosity of . We present measurements of W and Z cross sections and decay asymmetries, recent results in diboson physics with new limits on anomalous couplings, preliminary results on the direct determination of the W width, and preliminary studies for the W mass measurement
Dynamics of the triple contact line on a non-isothermal heater at partial wetting
The dynamics of the triple gas-liquid-solid contact line is analysed for the
case where the gas is the saturated vapour corresponding to the liquid, like in
the vapour bubble in boiling. It is shown that even small superheating (with
respect to the saturation temperature) causes evaporation of the adsorption
liquid film and the true triple contact is established. It is shown that the
hydrodynamic contact line singularity cannot be relaxed with the Navier slip
condition under such circumstances. Augmented with the second derivative slip
condition is proposed to be applied. For the partial wetting conditions, a
non-stationary contact line problem where the contact line motion is caused by
evaporation or condensation is treated in the lubrication approximation in the
vicinity of the contact line. High heat fluxes in this region require the
transient heat conduction inside the heater to be accounted for. Two 2D
problems, those of drop retraction with no phase change and of drop evaporation
are solved and analysed as illustrations of the proposed approach
Spectroscopy of nanoscopic semiconductor rings
Making use of self-assembly techniques, we demonstrate the realization of
nanoscopic semiconductor quantum rings in which the electronic states are in
the true quantum limit. We employ two complementary spectroscopic techniques to
investigate both the ground states and the excitations of these rings. Applying
a magnetic field perpendicular to the plane of the rings, we find that when
approximately one flux quantum threads the interior of each ring, a change in
the ground state from angular momentum to takes place.
This ground state transition is revealed both by a drastic modification of the
excitation spectrum and by a change in the magnetic field dispersion of the
single-electron charging energy
Radiative cascades in charged quantum dots
We measured, for the first time, two photon radiative cascades due to
sequential recombination of quantum dot confined electron hole pairs in the
presence of an additional spectator charge carrier. We identified direct, all
optical cascades involving spin blockaded intermediate states, and indirect
cascades, in which non radiative relaxation precedes the second recombination.
Our measurements provide also spin dephasing rates of confined carriers.Comment: 4 pages, 3 figure
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