Quantum theory of spontaneous and stimulated emission of surface plasmons

We introduce a quantization scheme that can be applied to surface waves propagating along a plane interface. An important result is the derivation of the energy of the surface wave for dispersive non-lossy media without invoking any specific model for the dielectric constant. Working in Coulomb's gauge, we use a modal representation of the fields. Each mode can be associated with a quantum harmonic oscillator. We have applied the formalism to derive quantum-mechanically the spontaneous emission rate of surface plasmon by a two-level system. The result is in very good agreement with Green's tensor approach in the non-lossy case. Green's approach allows also to account for losses, so that the limitations of a quantum approach of surface plasmons are clearly defined. Finally, the issue of stimulated versus spontaneous emission has been addressed. Because of the increasing density of states near the asymptote of the dispersion relation, it is quantitatively shown that the stimulated emission probability is too small to obtain gain in this frequency region.Comment: 14 pages, 5 figures, submitted to Phys. Rev. B

Green thermoelectrics: Observation and analysis of plant thermoelectric response

Plants are sensitive to thermal and electrical effects; yet the coupling of both, known as thermoelectricity, and its quantitative measurement in vegetal systems never were reported. We recorded the thermoelectric response of bean sprouts under various thermal conditions and stress. The obtained experimental data unambiguously demonstrate that a temperature difference between the roots and the leaves of a bean sprout induces a thermoelectric voltage between these two points. Basing our analysis of the data on the force-flux formalism of linear response theory, we found that the strength of the vegetal equivalent to the thermoelectric coupling is one order of magnitude larger than that in the best thermoelectric materials. Experimental data also show the importance of the thermal stress variation rate in the plant's electrophysiological response. Therefore, thermoelectric effects are sufficiently important to partake in the complex and intertwined processes of energy and matter transport within plants

Precision measurement of the CKM parameter sin() with the LHCb experiment

This thesis presents a decay-time dependent measurement of CP violation in the decay of B0 and B0-bar mesons into their common J/ψ KS final state. The CP observables S(J/ψ KS) and C(J/ψ KS) allow access to the magnitude of the symmetry violation in the interference between the B meson decay and mixing amplitudes and can directly be related to the CKM angle β. Using a dataset of selected signal B0 to J/ψ KS candidates corresponding to an integrated luminosity of 3.0 fb-1 collected at centre-of-mass energies of 7 and 8 TeV by the LHCb experiment, the CP observables are measured to be S(J/ψ KS) = -0.731 ± 0.035 (stat) ± 0.020 (syst), C(J/ψ KS) = -0.038 ± 0.032 (stat) ± 0.005 (syst), resulting in the worlds most precise measurement of these quantities at a hadron collider. With the parameter C(J/ψ S) fixed to zero, S(J/ψ KS) equals sin(2β) = 0.746 ± 0.030 (stat). The results have a similar precision as previous measurements at the B factories Babar and Belle and are consistent with these and with expectations from measurements of other CKM matrix parameters.Die vorliegende Dissertation beschreibt eine zerfallszeitabhängige Messung von CP-Verletzung im Zerfall von B0- und Anti-B0-Mesonen in ihren gemeinsamen Endzustand J/ψ KS. Die Größe der Symmetrieverletzung in der Interferenz der Zerfalls- und Mischungs-Amplituden der B-Mesonen lässt sich durch die CP-Observablen S(J/ψ KS) und C(J/ψ KS) ausdrücken und mit dem CKM-Winkel β in Bezug setzen. Die Messung wurde auf einem Datensatz von selektierten B0 nach J/ψ KS Signal-Kandidaten durchgeführt, der einer integrierten Luminosität von 3.0 fb-1 entspricht und bei Schwerpunktsenergien von 7 und 8 TeV am LHCb-Experiment aufgenommen wurde. Mit S(J/ψ KS) = -0.731 ± 0.035 (stat) ± 0.020 (syst), C(J/ψ KS) = -0.038 ± 0.032 (stat) ± 0.005 (syst), wurden die CP-Observablen mit einer Genauigkeit gemessen, die weltweit bisher an keinem anderen hadronischen Beschleuniger erreicht werden konnte. Unter der Annahme von C(J/ψ KS) = 0 folgt S(J/ψ KS) = sin(2β) = 0.746 ± 0.030 (stat). Die Ergebnisse sind von ähnlicher Präzision wie bisherige Messungen an den B-Fabriken Babar und Belle und sind bestens vereinbar mit diesen und Erwartungen aus Messungen von anderen CKM-Matrix-Parametern

On the weak coupling spectrum of N=2 supersymmetric SU(n) gauge theory

The weak coupling spectrum of BPS saturated states of pure $N=2$ supersymmetric SU$(n)$ gauge theory is investigated. The method uses known results on the dyon spectrum of the analogous theory with $N=4$ supersymmetry, along with the action on these states of the semi-classical monodromy transformations. For dyons whose magnetic charge is not a simple root of the Lie algebra, it is found that the weak coupling region is divided into a series of domains, for which the dyons have different electric charge, separated by walls on which the dyons decay. The proposed spectrum is shown to be consistent with the exact solution of the theory at strong coupling in the sense that the states at weak coupling can account for the singularities at strong coupling.Comment: 19 pages, plain tex with macro included, 6 figures included using psfig.te

Discrete transparent boundary conditions for the mixed KDV-BBM equation

International audienceIn this paper, we consider artificial boundary conditions for the linearized mixed Korteweg-de Vries (KDV) Benjamin-Bona-Mahoney (BBM) equation which models water waves in the small amplitude, large wavelength regime. Continuous (respectively discrete) artificial boundary conditions involve non local operators in time which in turn requires to compute time convolutions and invert the Laplace transform of an analytic function (respectively the Z-transform of an holomor-phic function). In this paper, we propose a new, stable and fairly general strategy to carry out this crucial step in the design of transparent boundary conditions. For large time simulations, we also introduce a methodology based on the asymptotic expansion of coefficients involved in exact direct transparent boundary conditions. We illustrate the accuracy of our methods for Gaussian and wave packets initial data

The Earth as an extrasolar transiting planet - II: HARPS and UVES detection of water vapor, biogenic O2_2, and O3_3

The atmospheric composition of transiting exoplanets can be characterized during transit by spectroscopy. For the transit of an Earth twin, models predict that biogenic $O_2$ and $O_3$ should be detectable, as well as water vapour, a molecule linked to habitability as we know it on Earth. The aim is to measure the Earth radius versus wavelength $\lambda$ - or the atmosphere thickness $h(\lambda)$ - at the highest spectral resolution available to fully characterize the signature of Earth seen as a transiting exoplanet. We present observations of the Moon eclipse of 21-12-2010. Seen from the Moon, the Earth eclipses the Sun and opens access to the Earth atmosphere transmission spectrum. We used HARPS and UVES spectrographs to take penumbra and umbra high-resolution spectra from 3100 to 10400 Ang. A change of the quantity of water vapour above the telescope compromised the quality of the UVES data. We corrected for this effect in the data processing. We analyzed the data by 3 different methods. The 1st method is based on the analysis of pairs of penumbra spectra. The 2nd makes use of a single penumbra spectrum, and the 3rd of all penumbra and umbra spectra. Profiles $h(\lambda)$ are obtained with the three methods for both instruments. The 1st method gives the best result, in agreement with a model. The second method seems to be more sensitive to the Doppler shift of solar spectral lines with respect to the telluric lines. The 3rd method makes use of umbra spectra which bias the result, but it can be corrected for this a posteriori from results with the first method. The 3 methods clearly show the spectral signature of the Rayleigh scattering in the Earth atmosphere and the bands of H$_2$O, O$_2$, and O$_3$. Sodium is detected. Assuming no atmospheric perturbations, we show that the E-ELT is theoretically able to detect the $O_2$ A-band in 8~h of integration for an Earth twin at 10pc.Comment: Final version accepted for publication in A&A - 21 pages, 27 figures. Abstract above slightly shortened wrt the original. The ArXiv version has low resolution figures, but a version with full resolution figures is available here: http://www.obs-hp.fr/~larnold/publi_to_download/eclipse2010_AA_v5_final.pd