Experimental results: an update

This article is a summary of experimental results from highest energy cosmic ray measurements, focusing on data and analyses that became available after 1999. To cite this article: R. Engel, H. Klages, C. R. Physique 5 (2004).     

Quarks and gluons: tests of QCD in e+e− annihilations

This article gives an overview of the main experimental tests of perturbative QCD performed at LEP. It covers the following topics: determination of α_s from event shapes, tests of flavour independence of α_s, studies of heavy quark mass effects, differences between quark and gluon jet fragmentation and study of the triple gluon vertex. To cite this article: D. Duchesneau et al., C. R. Physique 3 (2002) 1211–1222.     

Quantum transitions in bilayer states

The possible phase transitions when two layers at filling factor ν_t=1 are gradually separated are studied in this article. In the bosonic case the system should undergo a pairing transition from a Fermi liquid to an incompressible state. In the Fermionic case, the state evolves from an incompressible (1,1,1) state to a Fermi liquid. It is speculated that there is an intermediate phase involving charge two quasiparticles. To cite this article: V. Pasquier, C. R. Physique 3 (2002) 709–715.     

Calculation and error analysis for magnetic field parameters of a standard saddle coil

The calculation and measurement of field parameters and their derivatives play a very important role in designing and constructing saddle-shaped bipolar-magnetic coils [1]. In this article, new distribution function F_n and its derivatives along z-axis are defined, formularized and presented. Calculation and error analysis for the magnetic field parameters of a standard saddle coil are conducted and presented using the formulas. It is shown that the method and formulas can be used in calculating the field parameters, derivatives and the magnetic vector H for the bipolar-magnetic coils.     

Ab initio properties of gaseous helium

Recent ab initio calculations of the interaction potential of helium, and the effects of the new potentials on the calculated properties of helium gas (density and acoustic virials, viscosity, and thermal conductivity) are reviewed. To cite this article: J.B. Mehl, C. R. Physique 10 (2009).     

Quelques problèmes posés par les découvertes de Pluton et de Neptune

This Note reviews the history of the discovery of the planets Pluto and Neptune. To cite this article: V. Kourganoff, C. R. Physique 4 (2003).     

Colloidal quantum dots

The applications and physical properties of colloidal quantum dots are briefly reviewed and contrasted with those of Stransky–Krastanov grown quantum dots. To cite this article: P. Guyot-Sionnest, C. R. Physique 9 (2008).     

Probing spin physics in the quantum Hall regime by heat capacity and magnetotransport measurements

We review recent heat capacity and magnetotransport experiments on GaAs/AlGaAs heterostructures containing multilayer two-dimensional electron systems (2DESs) in the quantum Hall regime. Emphasis in this article is on the study of the heat capacity near Landau level filling factor ν=1. We also present a detailed survey of the development of the quantum Hall effect in tilted-magnetic fields for ν≲2. Among the novel phenomena we address is the strong coupling between the nuclear spins and the electrons associated with the spin phase transitions of the 2DES at ν=4/3 and near ν=1. To cite this article: S. Melinte et al., C. R. Physique 3 (2002) 667–676.     

Comment on “A new model of charge transfer during ice–ice collisions”: [C. R. Physique 3 (2002) 1293–1303]

A model which proposes modifications of a theory of collisional charging of ice is criticized. To cite this article: J.G. Dash, J.S. Wettlaufer, C. R. Physique 4 (2003).     

Séparation physique de molécules chirales

One examines the order of magnitude of the speed of separation of optically active molecules bearing a permanent dipole under the effect of a rotating electric field. To cite this article: Y. Pomeau, C. R. Physique 3 (2002) 1269–1271.     

A personal view of some issues involved in the structure of nuclei with large neutron excess

Large neutron excess poses new issues concerning the competition of deformation and pairing as well as changes in nuclear shell structure. To cite this article: I. Hamamoto, B.R. Mottelson, C. R. Physique 4 (2003).     

Towards a new kilogram definition based on a fundamental constant

The further development of the International System of Units and the redefinition of the mass unit based on a fundamental constant is a priority task of the metrology community. Two main strategies are pursued today, counting atoms and relating mechanical to electrical power. In this article the actual status of the kilogram and the different proposed methods are reviewed. To cite this article: W. Schwitz et al., C. R. Physique 5 (2004).     

Pfaffians,superpotentials and vector bundle moduli

We present a method for explicitly computing the non-perturbative superpotentials associated with the vector bundle moduli in heterotic superstrings and M-theory. This method is applicable to any stable, holomorphic vector bundle over an elliptically fibered Calabi–Yau threefold. Superpotentials of vector bundle moduli potentially have important implications for small instanton phase transitions and the vacuum stability and cosmology of superstrings and M-theory. To cite this article: B.A. Ovrut, C. R. Physique 4 (2003).     

Nonlinear electron transport in Si δ-doped GaAs

In this paper we report abnormal non-ohmic behaviour observed in Si δ-doped GaAs. We have performed measurements in Hall bar and Van der Pauw geometries in which electron transport phenomena can be studiekd by looking into the dependence of the device resistance R_xx on the applied current I or input power per electron, P. Transport of electrons in single Si δ-doped layers in GaAs, grown by MOCVD, in the linear and non-linear response regimes was studied. Our experimental results show that: i) R_xx dramatically decreases with increasingI (P) when sample current (input power) is larger than a critical value I_c (P_c); ii) I_c increases with electron density (Si δ-doping concentration); and iii) the decrease in R_xx with increasing I in the non-linear response regime can be observed both at zero and high magnetic fields over a wide temperature range. When R_xx is plotted as a function of the power loss rate per electron (P) the values of the critical power (P_c) for different samples are roughly the same. We suggest that redistribution of the ionised donors in the sample occurring when I >I_c takes the major responsibility for the observed abnormal phenomena.     

From quantum optics to quantum communications

We review the possible roles of quantum optics and quantum information methods for future developments of optical telecommunications. To cite this article: I. Abram, P. Grangier, C. R. Physique 4 (2003).     

Mechanical properties of carbon nanotubes: theoretical predictions and experimental measurements

Mechanical properties of carbon nanotubes are discussed based on recent advances in both modeling and experiment. To cite this article: R.S. Ruoff et al., C. R. Physique 4 (2003).     

Searching for extra dimensions at colliders

The phenomenology as well as the main experimental aspects of large extra space dimensions at colliders are briefly presented. To cite this article: M. Besançon, C. R. Physique 4 (2003).     

The Karlsruhe two-scale dynamo experiment

This article outlines the experimental realization of the Roberts–Busse kinematic dynamo model at the Forschungszentrum Karlsruhe. Essential observations of the spatial and temporal structures of the self-induced magnetic field and features of its saturation mechanism are presented and the experimental findings are compared with predictions from model calculations. To cite this article: U. Müller et al., C. R. Physique 9 (2008).     

North-South asymmetry of some solar parameters: A study based on the dominance of hemispheric sunspot activity during the solar cycles 18–24

Solar activity indices differ over the solar disk, and different activity parameters are not considered to be symmetric between the northern and southern solar hemispheres. In the present paper, the daily data of a set of solar parameters (solar radio flux F10.7, total solar irradiance TSI, plage area PA, coronal index CI, solar flare index SFI, and solar mean magnetic field ǀBǀ) as well as the daily hemispheric sunspot areas (SSAs) and sunspot numbers (SSNs) during a timeframe 1945–2017 (covering almost the last seven solar cycles, 18 ̶ 24) have been employed to investigate the north-south (N-S) asymmetry of the considered solar parameters based on the dominance of hemispheric distributions of SSAs and SSNs. The N-S asymmetry for each solar parameter has been investigated and the results revealed that it is a significant aspect through different years in the entire period. The grand average of each solar parameter for the northern and southern groups over each solar activity cycle has been calculated to investigate the statistical significance of N-S asymmetry of each solar parameter in each solar activity cycle. The solar cycles 19 and 24 displayed the dominance of the southern F10.7 and PA over the northern one. However, the solar cycle 23 showed the reverse. The grand average of CI displayed the southern preference in the solar cycle 19 while, the northern dominance of CI is revealed for the solar cycle 23. The grand averages of CI demonstrated nearly symmetric distribution in solar cycles 18, and 20–22. The N-S asymmetry of the grand averages of SFI exhibited a southern dominance during solar cycles 21 and 24. On the other hand, the northern preference is observed for the grand average of SFI through the solar cycle 23. The asymmetry of the grand averages of ǀBǀ obviously has the same dominance (sign) of hemispheric sunspot activity indices for the solar cycles 21–24. The periodic behavior of the N-S asymmetry of SSAs, SSNs, F10.7, and ǀBǀ has been investigated using Fast Fourier Transformation. Many mid- and long term periodicities have been detected. We present our results and discuss their possible explanations.     

Polarization fluctuations in regions bounded by equi-potentials

It is shown that the integral of <{P(rτ), P(r')}>· n? as a function of r over a volume V_e bounded by an equi-potential is independent of r' and of V_e and is determined solely by [?(ω)?1] · n? provided the dielectric constant is local and that V_e is of macroscopic dimensions.