Search for Higgs bosons decaying to WW in e+e- collisions at LEP
A search for Higgs bosons produced in association with a fermion pair, and decaying to WW, is performed with the data collected by the ALEPH detector at centre-of-mass energies ranging from 191 to 209 GeV. The data correspond to an integrated luminosity of 453.2 pb-1. Thirteen exclusive selections are developed according to the different final state topologies. No statistically significant evidence for a Higgs boson decaying into a WW pair has been found. An upper limit is derived, as a function of the Higgs boson mass, on the product of the e+e-→Hff̄ cross section and the H→WW branching ratio. The data on the search for H→WW are combined with previously published ALEPH results on the search for H→γγ, to significantly extend the limits on the mass of a fermiophobic Higgs boson.

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: 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: 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: 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: Possible evidence that pulsars are quark stars
abstract: It is a pity that the real state of matter in pulsar‐like stars is still not determined confidently because of the uncertainty about cold matter at supranuclear density, even 40 years after the discovery of pulsar. Nuclear matter (related to neutron stars) is one of the speculations for the inner constitution of pulsars even from the Landau's time more than 70 years ago, but quark matter (related to quark stars) is an alternative due to the fact of asymptotic freedom of interaction between quarks as the standard model of particle physics develops since 1960s. Therefore, one has to focus on astrophysical observations in order to answer what the nature of pulsars is. In this presentation, I would like to summarize possible observational evidence/hints that pulsar‐like stars could be quark stars, and to address achievable clear evidence for quark stars in the future experiments.

title: Can the Age Discrepancies of Neutron Stars Be Circumvented by an Accretion-assisted Torque?
abstract: It is found that 1E 1207.4-5209 could be a low-mass bare strange star if its small radius or low-altitude cyclotron formation can be identified. The age problems of five sources could be solved by a fossil-disk-assisted torque. The magnetic dipole radiation dominates the evolution of PSR B1757-24 at present, and the others are in propeller (or tracking) phases.

title: PSR B1828–11: a precession pulsar torqued by a quark planet?
abstract: The pulsar PSR B1828−11 has long-term, highly periodic and correlated variations in both pulse shape and the rate of slow-down. This phenomenon may provide evidence for the precession of the pulsar as suggested previously within the framework of free precession as well as forced. On a presumption of forced precession, we propose a quark planet model to this precession phenomenon instead, in which the pulsar is torqued by a quark planet. We construct this model by constraining the mass of the pulsar (Mpsr), the mass of the planet (Mpl) and the orbital radius of the planet (rpl). Five aspects are considered: the derived relation between Mpsr and rpl, the movement of the pulsar around the centre of mass, the ratio of Mpsr and Mpl, the gravitational wave radiation time-scale of the planetary system, and the death-line criterion. We also calculate the range of the precession period derivative and the gravitational wave strength (at earth) permitted by the model. Under reasonable parameters, the observed phenomenon can be understood by a pulsar (∼10 −4 ‐10 −1 M� ) with a quark planet (∼10 −8 ‐10 −3 M� ) orbiting it. According to the calculations presented, the pulsar would be a quark star because of its low mass, which might eject a lump of quark matter (to become an orbiting planet) during its birth.

title: To probe into pulsar's interior through gravitational waves
abstract: The gravitational radiation from compact pulsar-like stars depends on the state of dense matter at supranuclear densities, i.e., the nature of pulsar (e.g., either normal neutron stars or quark stars). The solid quark star model is focused for the nature of pulsar-like compact objects. Possible gravitational emission of quark stars (either fluid or solid) during the birth and later lifetime is discussed. Several observational features to distinguish various models for pulsar-like stars are proposed. It is suggested that the gravitational wave behaviors should be mass-dependent. Based on the data from the second LIGO science run, the upper limits of R  ·  θ 1/5 and thus M  ·  θ 3/5 ( M : mass, R : radius, and θ : wobble angle) are provided for those targets of millisecond pulsars.

title: The Birth of Quark Stars: Photon-driven Supernovae?
abstract: In this Letter we propose a possible mechanism for trying to alleviate the current difficulty in core-collapse supernovae by forming a strange quark star inside the collapsing core. Although the initial long-time cooling behavior of nascent strange stars is dominated by neutrino emissions, thermal emissions including photons and e± pair plasma do play a significant role in the explosion dynamics in this scenario. The key to promoting a successful shock outside a bare strange star is more likely to be the radiation pressure caused by thermal photons rather than neutrinos in conventional models. We observed through calculation that radiation pressure can push the overlying mantle away through photon-electron scattering with energy (the work done by radiation pressure) as much as ~1051 ergs if protoquark stars are born with temperatures higher than ~30-40 MeV. This result not only indicates that strange quark stars are bare since their formations, it could also provide a possible explanation for the formation of fireballs in cosmic long-soft γ-ray bursts associated with supernovae.