Measurement of the $\bar{B}^0$ and $B^{-}$ meson lifetimes
The lifetimes of the B0 and B- mesons are measured using a sample of about four million hadronic Z decays collected from 1991 to 19 95 with the ALEPH detector at LEP. The data sample has been recently reprocessed, achieving a substantial improvement in the tracking performance. Semileptonic decays of B0 and B- mesons are partially reconstructed by identifying events containing a lepton with an associated D* or D0 meson. The proper time of the B meson is estimated from the measured decay length and the momentum of the D-lepton system. A fit to the proper time of 1880 D* l- and 2856 D0 l- candidates yields the following results: tau B0 = 1.518 +- 0.053 +- 0.034 ps, tau B- = 1.648 +- 0.049 +- 0.035 ps, tau B- / tau B0 = 1.085 +- 0.059 +- 0.018.

title: Measurement of the tau lepton lifetime
abstract: The mean lifetime of the lepton is measured in a sample of 25700 pairs collected in 1992 with the ALEPH detector at LEP. A new analysis of the 1-1 topology events is introduced. In this analysis, the dependence of the impact parameter sum distribution on the daughter track momenta is taken into account, yielding improved precision compared to other impact parameter sum methods. Three other analyses of the oneand three-prong decays are updated with increased statistics. The measured lifetime is 293:5 3:1 1:7 fs. Including previous (1989{1991) ALEPH measurements, the combined lifetime is 293:7 2:7 1:6 fs.

title: Production of D**s mesons in hadronic Z decays
abstract: The production rates of the orbitally excited Ds** mesons, Ds1 and Ds2*, are measured with the 4.1 million hadronic Z decays recorded by the ALEPH detector during 1991--1995. The Ds** mesons are reconstructed in the decay modes Ds1+ -> D*+ K0, Ds1+ -> D*0 K+ and Ds2*+ -> D0 K+. The production rate of the Ds1 is measured to be n(Z->Ds1+-)=(0.52+-0.09+-0.06)%, under the assumption that the two considered decay modes of the Ds1 saturate the branching ratio. The production rate of the Ds2* is determined to be n(Z->Ds2*+-)=(0.83+-0.29+0.07-0.13)%, assuming that the branching fraction of the decay Ds2*+ -> D0 K+ is 45%. The production rates in Z->cc and Z->bbar decays are measured separately.

title: Charm counting in b decays
abstract: The inclusive production of charmed particles in decays has been measured from the yield of D0, D+, Ds+ and Λc+ decays in a sample of events with high b purity collected with the ALEPH detector from 1992 to 1995. From these measurements, adding the charmonia production rate and an estimate of the charmed strange baryon contribution, the average number of charm quarks per b decay is determined to be nc = 1.230 ± 0.036 ± 0.038 ± 0.053, where the uncertainties are due to statistics, systematic effects and branching ratios, respectively.

title: A precise determination of the number of families with light neutrinos and of the Z boson partial widths
abstract: More extensive and precise results are reported on the parameters of Z decay. On the basis of 20 000 Z decays collected with the ALEPH detector at LEP we find Mz=91.182±0.026 (exp.) ±0.030 (beam) GeV, Γz=2.541±0.056 GeV and σhad0=41.4±0.8 nb. The partial widths for the hadronic and leptonic channels are Γhad=1804±44 MeV, Γe+e−=82.1±3.4 MeV, Γμ+μ−=87.9±6.0 MeV and Γτ+τ−=86.1±5.6 MeV, in good agreement with the standard model. On the basis of the average leptonic width Γl+l−=83.9±2.2 MeV, the effective weak mixing angle is found to be sin2θw(Mz)=0.231±0.008. Usin g the partial widths calculated in the standard model, the number of light neutrino families is Nν=3.01±0.15 (exp.)±0.05 (theor.).

title: Measurement of W pair production in e+ e- collisions at 183-GeV
abstract: The production of W + W − pairs is analysed in a data sample collected by ALEPH at a mean centre-of-mass energy of 182.7 GeV, corresponding to an integrated luminosity of 57 pb −1 . Cross sections are given for different topologies of W decays into leptons or hadrons. Under Standard Model assumptions for the W-pair production and decay, the W-pair cross section is measured to be 15.57±0.62 (stat.) ±0.29 (syst.) pb . Using also the W-pair data samples collected by ALEPH at lower centre-of-mass energies, the decay branching ratio of the W boson into hadrons is measured to be B(W→hadrons) =68.93±1.21 (stat.) ±0.51 (syst.) % , allowing a determination of the CKM matrix element |V cs |=1.043±0.058 (stat.) ±0.026 (syst.) . The agreement of the cross sections with the Standard Model prediction allows a limit to be set on the W decay rate to undetectable final states.

title: RADIATIVE ACTIVITY OF MAGNETIC WHITE DWARF UNDERGOING LORENTZ-FORCE-DRIVEN TORSIONAL VIBRATIONS
abstract: We study radiative activity of magnetic white dwarf undergoing torsional vibrations about axis of its own dipole magnetic moment under the action of Lorentz restoring force. It is shown that pulsating white dwarf can convert its vibration energy into the energy of magneto-dipole emission, oscillating with the frequency equal to the frequency of Alfven torsional vibrations, provided that internal magnetic field is decayed. The most conspicuous feature of the vibration energy powered radiation in question is the lengthening of periods of oscillating emission; the rate of period elongation is determined by the rate magnetic field decay.

title: Towards the properties of long gamma-ray burst progenitors with Swift data
abstract: We investigate the properties of both the prompt and X-ray afterglows of gamma-ray bursts (GRBs) in the burst frame with a sample of 33 Swift GRBs. Assuming that the steep decay segment in the canonical X-ray afterglow light curves is due to the curvature effect, we fit the light curves with a broken power law to derive the zero time of the last emission epoch of the prompt emission (t 1 ) and the beginning as well as the end time of the shallow decay segment (t 2 and t 3 ). We show that both the isotropic peak gamma-ray luminosity (L peak,γ ) and gamma-ray energy (E iso,γ ) are correlated with the isotropic X-ray energy (E iso,γ ) of the shallow decay phase and the isotropic X-ray luminosity at t 2 (L x ,t 2 ). We infer the properties of the progenitor stars based on a model proposed by Kumar et al. who suggested that both the prompt gamma-rays and the X-ray afterglows are due to the accretions of different layers of materials of the GRB progenitor star by a central black hole (BH). We find that most of the derived masses of the core layers are M c = 0.1 ~ 5 M ☉ , and their average accretion rates in the prompt gamma-ray phase are M c = 0.01~ 1 M ☉ s -1 , with a radius of r c = 10 8 ~ 10 10 cm. The rotation parameter is correlated with the burst duration, being consistent with the expectation of collapsar models. The estimated radii and the masses of the fall-back materials for the envelope layers are r e = 10 10 ~ 10 12 cm and M e = 10 -3 ~ 1 M ☉ , respectively. The average accretion rates in the shallow decay phase are correlated with those in the prompt gamma-ray phase, but they are much lower, i.e. M e = 10 -8 ~ 10 -4 M ☉ s -1 . The r e values are smaller than the photospheric radii of Wolf-Rayet stars. In our calculation, we assume a uniform mass of the central BH (M BH = 10M ☉ ). Therefore, we may compare our results with simulation results. It is interesting that the assembled mass density profile for the bursts in our sample is well consistent with the simulation for a pre-supernova star with mass M = 25M ☉ .

title: 1E 1207.4-5209: a low-mass bare strange star?
abstract: Both rotation- and accretion-powered low-mass bare strange stars are studied, with particular regard to their astrophysical appearance. It is suggested that low-mass bare strange stars, with weaker ferromagnetic fields than that of normal pulsars, could result from the accretioninduced collapse of white dwarfs. According to its peculiar timing behaviour, we propose that the radio-quiet object, 1E 1207.4−5209, could be a low-mass bare strange star with a polar surface magnetic field of ∼6 × 10 10 G and a radius of a few kilometres. The low-mass bare strange star idea is helpful in distinguishing neutron and strange stars, and is testable by imaging pulsar-like stars with the future Constellation-X telescope. Ke yw ords: dense matter ‐ elementary particles ‐ stars: neutron ‐ pulsars: general ‐ pulsars: individual: 1E 1207.4−5209.

title: Nucleon sea in the effective chiral quark model
abstract: The asymmetries of both light-flavor antiquark d(x)-u(x) and strange-antistrange s(x)-s(x) distributions of the nucleon sea are considered with more details in the effective chiral quark model. We find that the asymmetric distribution of light-flavor antiquarks d(x)-u(x) matches the experimental data well and that the asymmetry of strange and antistrange distributions can bring about 60%-100% correction to the NuTeV anomaly of sin{sup 2}{theta}{sub w}, which are 3 standard deviations from the world average value measured in other electroweak processes. The results on the correction to the NuTeV anomaly are insensitive to the inputs of the constituent quark distributions and the cutoff parameters. The ratios of d(x)/u(x) and s(x)/s(x) are also discussed, and it is found that the ratio s(x)/s(x) is compatible with the available experiments with an additional symmetric sea contribution being considered effectively.

title: Experimental measurement of the mass of the tau lepton at the Beijing Electron Positron Collider (BEPC)