Measurements of the CKM angle phi_3/gamma

We present a review on the measurements of the CKM angle gamma (phi_3) as performed by the BABAR and Belle experiments at the asymmetric-energy e+e- B factories colliders PEP-II and KEKB.Comment: 11 pages, 10 figures, proceedings of the 5th Flavor Physics And CP Violation Conference (FPCP 2007

Space based microlensing planet searches

The discovery of extra-solar planets is arguably the most exciting development in astrophysics during the past 15 years, rivalled only by the detection of dark energy. Two projects unite the communities of exoplanet scientists and cosmologists: the proposed ESA M class mission EUCLID and the large space mission WFIRST, top ranked by the Astronomy 2010 Decadal Survey report. The later states that: "Space-based microlensing is the optimal approach to providing a true statistical census of planetary systems in the Galaxy, over a range of likely semi-major axes". They also add: "This census, combined with that made by the Kepler mission, will determine how common Earth-like planets are over a wide range of orbital parameters". We will present a status report of the results obtained by microlensing on exoplanets and the new objectives of the next generation of ground based wide field imager networks. We will finally discuss the fantastic prospect offered by space based microlensing at the horizon 2020-2025.Comment: 8 pages, Proceedings to the ROPACS meeting "Hot Planets and Cool Stars" (Nov. 2012, Garching), invited contributio

Charmed-B decays at BaBar

We present recent results on charmed-B decays using data collected by the BaBa

Beyond Gravitoelectromagnetism: Critical Speed in Gravitational Motion

A null ray approaching a distant astronomical source appears to slow down, while a massive particle speeds up in accordance with Newtonian gravitation. The integration of these apparently incompatible aspects of motion in general relativity is due to the existence of a critical speed. Dynamics of particles moving faster than the critical speed could then be contrary to Newtonian expectations. Working within the framework of gravitoelectromagnetism, the implications of the existence of a critical speed are explored. The results are expected to be significant for high energy astrophysics.Comment: 13 pages, to appear in the Special December 2005 Issue of Int. J. Mod. Phys.

Adaptation de la mesure potentiométrique à l'estimation en continu de la teneur en cuivre de solutions aqueuses présentant de fortes variations physico-chimiques

La mesure en continu, sans prélèvement et sous conditions physico-chimiques variables, de la teneur en cuivre d'une solution aqueuse, constitue le cadre de ce travail. La méthode d'estimation proposée est basée sur la potentiométrie sélective à l'aide d'une électrode spécifique au cuivre. Le comportement de l'électrode est modélisé par une loi non linéaire s'inspirant de la relation de Nernst généralisée. Le modèle intègre les paramètres température, conductivité et pH de la solution. Il rend possible une estimation de la concentration totale de cuivre même en présence de complexations hydroxyles. La phase de modélisation est présentée en détail. Les performances de l'estimateur sont évaluées puis discutées.Ion Selective electrodes (ISEs) offer an attractive solution for continuously evaluating the content of certain ionic species in aqueous media. Manufacturers propose a wide range of electrodes specific to heavy metals (Cu2+, Pb2+ …). Because they eliminate the need for sampling, are of reasonable size and have few electronic parts, ISEs seem highly appropriate for continuous monitoring in urban purification systems. Measurements obtained by these sensors in controlled media in the laboratory are usually precise, reliable and reproducible. However, it is not so with complex and uncontrolled media. This work falls within the general scope of the continuous measurement of heavy metals in wastewater. More particularly, it is devoted to the description of the behaviour of a copper-selective electrode (ISECu) in a medium presenting wide physicochemical variations.Experimental set-upIn order to study ISE behaviour, we developed an experimental platform that allowed us to reproduce in a reactor the physicochemical variations observed in wastewater, particularly with regards to salinity and acidity. The reactor was fitted with a measuring set consisting of five electrodes that measured the following parameters: pH (ref. integrated Ag/Agcl), redox (red), ISECu (ECu), temperature (T) and conductivity (s). A computer system carried out the acquisition of the five signals with a 10-second sampling period. The species concentration in the reactor was determined by calculating the weight of the solutions extracted from or injected into the reactor. Controlling the temperature of the system was undertaken using a cryostat. Sequential tests allowed the pH, redox potential and conductivity of the medium to be varied and were carried out by successive injections of different chemical products. The response times of the conductivity probe and of the pH and redox electrodes are shown here; the short response time of the sensors (20 to 30 s) and the strong correlation between the measured pH and redox are noted. ISE modellingThe model used to explain the ISE response is based on a generalization of Nernst's Law that takes into account the temperature and the activity of the free ions (Cu2+). Taking into consideration chemical equilibria and mass equations allowed us to link the activity of the free copper ions to the total injected copper concentration |Cu2+|tot and to the pH. Redox, strongly correlated to pH, was ignored in the mathematical model. Since hydroxyl complexation is the major complexation reaction (compared to other copper-binding ligands), the potential measured with the ISE took the following form:ECu=b0+b1T.log[(ϒ2|Cu2+|tot) / (1+b2ϒ210pH+b3ϒ2102pH) + b4]The activity coefficient ϒ2 of the Cu2+ ions was calculated from the ionic strength (I) of the solution, using the Debye-Hückel approximation. Ionic strength was derived from conductivity corrected to 25 °C. In wastewater, the ranges of the physicochemical parameters were as follows: T from 5 to 35°C; pH from 4 to 9; Omega from 500 to 2000 mS/cm; redox from 400 to -400 mV/ENH; and copper concentrations 10-3 mol/dm3.In order to identify the bi coefficients of the model, we established an experimental plan comprising 108 measurement points that covered, with a minimal number of experiments, the ranges of variations of the parameters of influence. A dispersion diagram of measured and modelled values gave a linear adjustment coefficient close to 0.99 and a standard deviation of 8.8 mV, which corresponds to a 0.34 decadal standard error in the concentration estimate. With a temperature of 25 °C, the model has a sensitivity of -26.4 mV/decade, very close to the theoretical slope of an electrode sensitive to divalent ions.ISE measurement of the copper concentration with large pH variations pH is the parameter which exerts the greatest influence on ISE response, which is why tests simulating copper pollution with large variations of pH were carried out. These tests enabled us to evaluate the performances of the model in terms of the estimation of copper content. Four solutions of total copper concentration equal to 10-6, 10-5, 10-4, 10-3 mol/dm3 respectively, were used. Their temperature was 25 °C and their conductivity was fixed at approximately 500 mS/cm. We varied the pH of each solution between 4 and 10. For the four tests, we show the estimate of the copper concentration obtained with our model starting from the potential measured by the ISE.In the case of strong copper pollution (10-3 mol/dm3), the model yields an overestimated concentration below pH 7 with a decadal error of less than 0.5. Above pH 7, the concentration is underestimated while maintaining a decadal error of less than 0.5. At pH 7, a 0.04-decade minimal error is found. For pollution equal to or less than 10-4 mol/dm3, the model gives good results in an acid or neutral medium with a decadal error usually less than 0.3. In an alkaline medium, concentration is overestimated. In this case the error increases in a roughly linear manner with the pH and the co-logarithm of copper concentration. From the results of these tests, we defined a valid domain of ISE copper concentration measurement using our model. In conclusion, the suggested method, although not very accurate, could be used as an indicator of the copper concentration level in wastewater. The ISE-response correction model is currently being tested under operational conditions at a water treatment plant in Nancy-Maxéville (France)

Measurement of the CKM-angle gamma at BABAR

The authors present the results of the measurements employed by the BABAR Collaboration, to determine the value of the Cabibbo-Kobayashi-Maskawa (CKM) CP-violating phase {gamma} ({triple_bond} arg [-V{sub ud}V*{sub ub}/V{sub cd}V*{sub cb}]). These measurements are based on the studies performed with the charged B-decays B{sup -} {yields} {tilde D}{sup 0} K{sup -}, B{sup -} {yields} {tilde D}*{sup 0} K*{sup -}, where {tilde D}{sup 0} indicates either a D{sup 0} or a {bar D}{sup 0} meson. A sample of about 230 million B{bar B} pairs collected by the BABAR detector [1], at the PEP-II asymmetric-energy e{sup +}e{sup -} collider at SLAC, is used