H.E.S.S.—the high energy stereoscopic system—is a new system of large atmospheric Cherenkov telescopes for GeV/TeV astronomy. Each of the four telescopes of 107 m2 mirror area is equipped with a 960-pixel photomultiplier-tube camera. This paper describes the methods used to convert the photomultiplier signals into the quantities needed for Cherenkov image analysis. Two independent calibration techniques have been applied in parallel to provide an estimation of uncertainties. Results on the long-term stability of the H.E.S.S. cameras are also presented.

We report the detection of a point-like source of very high energy (VHE) gamma-rays coincident within 1' of Sgr A*, obtained with the H.E.S.S. array of Cherenkov telescopes. The gamma-rays exhibit a power-law energy spectrum with a spectral index of -2.2 +/- 0.09 +/- 0.15 and a flux above the 165 GeV threshold of (1.82 +/- 0.22) \times 10^{-7} m^{-2} s^{-1}. The measured flux and spectrum differ substantially from recent results reported in particular by the CANGAROO collaboration.

Exotic hadrons made of five quarks (pentaquarks) are searched for in hadronic Z decays collected by the ALEPH detector at LEP. No significant signal is observed. At 95% C.L., upper limits are set on the production rates N of such particles and their charge-conjugate state per Z decay: N Theta(1535)+ . BR(Theta(1535)^+ -> pK0s < 6.2 x 10^-4, N Xi(1862)-- . BR(Xi(1862)^-- -> xi^- pi^-) < 4.5 x 10^-4, N Xi(1862)^0 . BR(Xi(1862)^0 -> Xi^-pi^+ < 8.9 x 10^-4, N Theta_c(3100)^0 . BR(Theta_c(3100)^0 -> D*-p) < 6.3 x 10^-4, N Theta_c(3100)^0 . BR(Theta_c(3100)^0 -> D^-p) < 31 x 10^-4.

The W+W- production cross section is measured from a data sample corresponding to a total integrated luminosity of 683 pb-1, collected by the Aleph experiment at LEP at centre-of-mass energies from 183 to 209 GeV. Individual cross sections for the different topologies arising from W decays into leptons or hadrons, as well as the total W-pair cross section are given at eight centre-of-mass energies. The results are found to be in agreement with recently developed Standard Model calculations at the one percent level. The branching fraction of the W boson into hadrons is measured to be B (W--> hadrons) = (67.15 +- 0.37(stat) +- 0.15(syst))%, from which the CKM matrix element |Vcs| is determined to be 0.959 +- 0.017(stat) +- 0.008(syst).

The hadronic final states observed with the ALEPH detector at LEP in e+e- annihilation are analysed using 730 pb-1 of data collected between 91 and 209 GeV in the framework of QCD. In particular event-shape variables and inclusive charged particle spectra are measured. The energy evolution of quantities derived from these measurements is compared to analytic QCD predictions. The mean charged particle multiplicity, the charged particle momentum spectrum and its peak position are compared to predictions of the modified-leading-logarithmic approximation. The strong coupling constant alpha_s is determined from a fit of the QCD prediction to distributions of six event-shape variables at eight centre-of-mass energies. A study of non-perturbative power law corrections is presented

Bose-Einstein correlations are studied in pairs of charged pions from hadronic Z decays, collected by the ALEPH detector.The correlation function, measured using either the unlike-sign or the mixed reference sample, is studied in terms of the Lorentz-invariant four-momentum difference and its transverse, $Q_{\textrm{T}}$, and longitudinal, $Q_{\textrm{L}}$, components with respect to the longitudinal centre-of-mass system. Values for the correlation radii, $R_{\textrm{T}}$ and $R_{\textrm{L}}$, are obtained from the fit of the Goldhaber parametrisation.The results indicate that the correlation radii values depend on the chosen kind of reference sample and on the two-jet purity.

The rate of gluons splitting into $c \bar{c}$ pairs in hadronic $Z$ decays is measured using the data sample collected by ALEPH from 1991 to 1995. The selection is based on the identification of leptons (electrons and muons) originating from semileptonic charm decays, and on the topological properties of signal events. The result derived from the selected sample is $g_{c \bar{c}}=(3.26 \pm 0.23 \rm{(stat)} \pm 0.42 \rm{(syst)}) %$