121677731
A direct measurement of |Vcs| in hadronic W decays using a charm tag
Abstract The inclusive charm production rate in W decays is measured from a study of the properties of final state particles. The sample of W pairs is selected from 67.7 pb −1 collected by ALEPH in 1996 and 1997 at centre-of-mass energies near 172 and 183 GeV in the channels W + W − →4q and W + W − →lνq q . The branching fraction of hadronic W decays to a final state containing a c quark, R W c = Γ(W→cX)/Γ(W→hadrons), is measured to be 0.51±0.05 stat ±0.03 syst . This allows a direct determination of the CKM matrix element |V cs |=1.00±0.11 stat ±0.07 syst .
123148086
Charm counting in b decays
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.
144007210
A precise determination of the number of families with light neutrinos and of the Z boson partial widths
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.).
122002257
Production of D**s mesons in hadronic Z decays
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.
15227858
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.
91183149
Measurement of the tau lepton lifetime
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. (Submitted to Physics Letters B) See the following pages for the list of authors. The ALEPH Collaboration D. Buskulic, D. Casper, I. De Bonis, D. Decamp, P. Ghez, C. Goy, J.-P. Lees, A. Lucotte, M.-N. Minard, P. Odier, B. Pietrzyk Laboratoire de Physique des Particules (LAPP), INP-CNRS, 74019 Annecy-le-Vieux Cedex, France F. Ariztizabal, M. Chmeissani, J.M. Crespo, I. Efthymiopoulos, E. Fernandez, M. Fernandez-Bosman, V. Gaitan, Ll. Garrido, M. Martinez, S. Orteu, A. Pacheco, C. Padilla, F. Palla, A. Pascual, J.A. Perlas, F. Sanchez, F. Teubert Institut de Fisica d'Altes Energies, Universitat Autonoma de Barcelona, 08193 Bellaterra (Barcelona), Spain A. Colaleo, D. Creanza, M. de Palma, A. Farilla, G. Gelao, M. Girone, G. Iaselli, G. Maggi, M. Maggi, N. Marinelli, S. Natali, S. Nuzzo, A. Ranieri, G. Raso, F. Romano, F. Ruggieri, G. Selvaggi, L. Silvestris, P. Tempesta, G. Zito Dipartimento di Fisica, INFN Sezione di Bari, 70126 Bari, Italy X. Huang, J. Lin, Q. Ouyang, T. Wang, Y. Xie, R. Xu, S. Xue, J. Zhang, L. Zhang, W. Zhao Institute of High-Energy Physics, Academia Sinica, Beijing, The People's Republic of China G. Bonvicini, M. Cattaneo, P. Comas, P. Coyle, H. Drevermann, A. Engelhardt, R.W. Forty, M. Frank, R. Hagelberg, J. Harvey, R. Jacobsen, P. Janot, B. Jost, E. Kneringer, J. Knobloch, I. Lehraus, C. Markou, E.B. Martin, P. Mato, A. Minten, R. Miquel, T. Oest, P. Palazzi, J.R. Pater, J.F. Pusztaszeri, F. Ranjard, P. Rensing, L. Rolandi, D. Schlatter, M. Schmelling, O. Schneider, W. Tejessy, I.R. Tomalin, A. Venturi, H. Wachsmuth, W. Wiedenmann, T. Wildish, W. Witzeling, J. Wotschack European Laboratory for Particle Physics (CERN), 1211 Geneva 23, Switzerland Z. Ajaltouni, M. Bardadin-Otwinowska, A. Barres, C. Boyer, A. Falvard, P. Gay, C. Guicheney, P. Henrard, J. Jousset, B. Michel, S. Monteil, J-C. Montret, D. Pallin, P. Perret, F. Podlyski, J. Proriol, J.-M. Rossignol, F. Saadi Laboratoire de Physique Corpusculaire, Universit e Blaise Pascal, INP-CNRS, Clermont-Ferrand, 63177 Aubi ere, France T. Fearnley, J.B. Hansen, J.D. Hansen, J.R. Hansen, P.H. Hansen, B.S. Nilsson Niels Bohr Institute, 2100 Copenhagen, Denmark A. Kyriakis, E. Simopoulou, I. Siotis, A. Vayaki, K. Zachariadou Nuclear Research Center Demokritos (NRCD), Athens, Greece A. Blondel, G. Bonneaud, J.C. Brient, P. Bourdon, L. Passalacqua, A. Roug e, M. Rumpf, R. Tanaka, A. Valassi, M. Verderi, H. Videau Laboratoire de Physique Nucl eaire et des Hautes Energies, Ecole Polytechnique, INP-CNRS, 91128 Palaiseau Cedex, France D.J. Candlin, M.I. Parsons Department of Physics, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom E. Focardi, G. Parrini Dipartimento di Fisica, Universit a di Firenze, INFN Sezione di Firenze, 50125 Firenze, Italy M. Corden, M. Del no, C. Georgiopoulos, D.E. Ja e Supercomputer Computations Research Institute, Florida State University, Tallahassee, FL 323064052, USA 13;14 A. Antonelli, G. Bencivenni, G. Bologna, F. Bossi, P. Campana, G. Capon, V. Chiarella, G. Felici, P. Laurelli, G. Mannocchi, F. Murtas, G.P. Murtas, M. Pepe-Altarelli Laboratori Nazionali dell'INFN (LNF-INFN), 00044 Frascati, Italy S.J. Dorris, A.W. Halley, I. ten Have, I.G. Knowles, J.G. Lynch, W.T. Morton, V. O'Shea, C. Raine, P. Reeves, J.M. Scarr, K. Smith, M.G. Smith, A.S. Thompson, F. Thomson, S. Thorn, R.M. Turnbull Department of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ,United Kingdom U. Becker, O. Braun, C. Geweniger, G. Graefe, P. Hanke, V. Hepp, E.E. Kluge, A. Putzer, B. Rensch, M. Schmidt, J. Sommer, H. Stenzel, K. Tittel, S. Werner, M. Wunsch Institut f ur Hochenergiephysik, Universitat Heidelberg, 69120 Heidelberg, Fed. Rep. of Germany R. Beuselinck, D.M. Binnie, W. Cameron, D.J. Colling, P.J. Dornan, N. Konstantinidis, L. Moneta, A. Moutoussi, J. Nash, G. San Martin, J.K. Sedgbeer, A.M. Stacey Department of Physics, Imperial College, London SW7 2BZ, United Kingdom G. Dissertori, P. Girtler, D. Kuhn, G. Rudolph Institut f ur Experimentalphysik, Universitat Innsbruck, 6020 Innsbruck, Austria C.K. Bowdery, T.J. Brodbeck, P. Colrain, G. Crawford, A.J. Finch, F. Foster, G. Hughes, T. Sloan, E.P. Whelan, M.I. Williams Department of Physics, University of Lancaster, Lancaster LA1 4YB, United Kingdom A. Galla, A.M. Greene, K. Kleinknecht, G. Quast, J. Raab, B. Renk, H.-G. Sander, R. Wanke, P. van Gemmeren C. Zeitnitz Institut f ur Physik, Universitat Mainz, 55099 Mainz, Fed. Rep. of Germany J.J. Aubert, A.M. Bencheikh, C. Benchouk, A. Bonissent, G. Bujosa, D. Calvet, J. Carr, C. Diaconu, F. Etienne, M. Thulasidas, D. Nicod, P. Payre, D. Rousseau, M. Talby Centre de Physique des Particules, Facult e des Sciences de Luminy, INP-CNRS, 13288 Marseille, France I. Abt, R. Assmann, C. Bauer, W. Blum, D. Brown, H. Dietl, F. Dydak, G. Ganis, C. Gotzhein, K. Jakobs, H. Kroha, G. L utjens, G. Lutz, W. M anner, H.-G. Moser, R. Richter, A. Rosado-Schlosser, S. Schael, R. Settles, H. Seywerd, R. St. Denis, G. Wolf Max-Planck-Institut f ur Physik, Werner-Heisenberg-Institut, 80805 M unchen, Fed. Rep. of Germany R. Alemany, J. Boucrot, O. Callot, A. Cordier, F. Courault, M. Davier, L. Du ot, J.-F. Grivaz, Ph. Heusse, M. Jacquet, D.W. Kim, F. Le Diberder, J. Lefran cois, A.-M. Lutz, G. Musolino, I. Nikolic, H.J. Park, I.C. Park, M.-H. Schune, S. Simion, J.-J. Veillet, I. Videau Laboratoire de l'Acc el erateur Lin eaire, Universit e de Paris-Sud, INP-CNRS, 91405 Orsay Cedex, France D. Abbaneo, P. Azzurri, G. Bagliesi, G. Batignani, S. Bettarini, C. Bozzi, G. Calderini, M. Carpinelli, M.A. Ciocci, V. Ciulli, R. Dell'Orso, R. Fantechi, I. Ferrante, F. Fidecaro, L. Fo a, F. Forti, A. Giassi, M.A. Giorgi, A. Gregorio, F. Ligabue, A. Lusiani, P.S. Marrocchesi, A. Messineo, G. Rizzo, G. Sanguinetti, A. Sciab a, P. Spagnolo, J. Steinberger, R. Tenchini, G. Tonelli, G. Triggiani, C. Vannini, P.G. Verdini, J. Walsh Dipartimento di Fisica dell'Universit a, INFN Sezione di Pisa, e Scuola Normale Superiore, 56010 Pisa, Italy A.P. Betteridge, G.A. Blair, L.M. Bryant, F. Cerutti, Y. Gao, M.G. Green, D.L. Johnson, T. Medcalf, Ll.M. Mir, P. Perrodo, J.A. Strong Department of Physics, Royal Holloway & Bedford New College, University of London, Surrey TW20 OEX, United Kingdom V. Bertin, D.R. Botterill, R.W. Cli t, T.R. Edgecock, S. Haywood, M. Edwards, P. Maley, P.R. Norton, J.C. Thompson Particle Physics Dept., Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 OQX, United Kingdom B. Bloch-Devaux, P. Colas, S. Emery, W. Kozanecki, E. Lan con, M.C. Lemaire, E. Locci, B. Marx, P. Perez, J. Rander, J.-F. Renardy, A. Roussarie, J.-P. Schuller, J. Schwindling, A. Trabelsi, B. Vallage CEA, DAPNIA/Service de Physique des Particules, CE-Saclay, 91191 Gif-sur-Yvette Cedex, France R.P. Johnson, H.Y. Kim, A.M. Litke, M.A. McNeil, G. Taylor Institute for Particle Physics, University of California at Santa Cruz, Santa Cruz, CA 95064, USA A. Beddall, C.N. Booth, R. Boswell, S. Cartwright, F. Combley, I. Dawson, A. Koksal, M. Letho, W.M. Newton, C. Rankin, L.F. Thompson Department of Physics, University of She eld, She eld S3 7RH, United Kingdom A. Bohrer, S. Brandt, G. Cowan, E. Feigl, C. Grupen, G. Lutters, J. Minguet-Rodriguez, F. Rivera, P. Saraiva, L. Smolik, F. Stephan, Fachbereich Physik, Universitat Siegen, 57068 Siegen, Fed. Rep. of Germany M. Apollonio, L. Bosisio, R. Della Marina, G. Giannini, B. Gobbo, F. Ragusa Dipartimento di Fisica, Universit a di Trieste e INFN Sezione di Trieste, 34127 Trieste, Italy J. Rothberg, S. Wasserbaech Experimental Elementary Particle Physics, University of Washington, WA 98195 Seattle, U.S.A. S.R. Armstrong, L. Bellantoni, P. Elmer, Z. Feng, D.P.S. Ferguson, Y.S. Gao, S. Gonz alez, J. Grahl, J.L. Harton, O.J. Hayes, H. Hu, P.A. McNamara III, J.M. Nachtman, W. Orejudos, Y.B. Pan, Y. Saadi, M. Schmitt, I.J. Scott, V. Sharma, J.D. Turk, A.M. Walsh, Sau Lan Wu, X. Wu, J.M. Yamartino, M. Zheng, G. Zobernig Department of Physics, University of Wisconsin, Madison, WI 53706, USA Now at CERN, 1211 Geneva 23, Switzerland. Deceased. Now at Dipartimento di Fisica, Universit a di Lecce, 73100 Lecce, Italy. Also Istituto di Fisica Generale, Universit a di Torino, Torino, Italy. Also Istituto di Cosmo-Geo sica del C.N.R., Torino, Italy. Supported by the Commission of the European Communities, contract ERBCHBICT941234. Supported by CICYT, Spain. Supported by the National Science Foundation of China. Supported by the Danish Natural Science Research Council. Supported by the UK Particle Physics and Astronomy Research Council. Supported by the US Department of Energy, grant DE-FG0295-ER40896. On leave from Universitat Autonoma de Barcelona, Barcelona, Spain. Supported by the US Department of Energy, contract DE-FG05-92ER40742. Supported by the US Department of Energy, contract DE-FC05-85ER250000. Permanent address: Universitat de Barcelona, 08208 Barcelona, Spain. Supported by the Bundesministerium f ur Forschung und Technologie, Fed. Rep. of Germany. Supported by the Direction des Sciences de la Mati ere, C.E.A. Supported by Fonds zur F orderung der wissenschaftlichen Forschung, Austria. Permanent address: Kangnung National University, Kangnung, Korea. Now at Dipartimento di Fisica, Universit a di Milano, Milano, Italy. Also at CERN, 1211 Geneva 23, Switzerland. Supported by the US Department of Energy, grant DE-FG0
125575431
Measurement of the branching ratios for J / psi --> gamma pi0, gamma eta, gamma eta' --> 3gamma on the BES
119102102
Absorption features caused by oscillations of electrons on the surface of a quark star
If quark stars exist, they may be enveloped in thin electron layers (electron seas), which uniformly surround the entire star. These layers will be affected by the magnetic fields of quark stars in such a way that the electron seas would transmit hydromagnetic cyclotron waves, as studied in this paper. Particular attention is devoted to vortex hydrodynamical oscillations of the electron sea. The frequency spectrum of these oscillations is derived in analytic form. If the thermal X-ray spectra of quark stars are modulated by vortex hydrodynamical vibrations, the thermal spectra of compact stars, foremost central compact objects (CCOs) and X-ray dim isolated neutron stars (XDINSs), could be used to verify the existence of these vibrational modes observationally. The central compact object 1E 1207.4-5209 appears particularly interesting in this context, since its absorption features at 0.7 keV and 1.4 keV can be comfortably explained in the framework of the hydro-cyclotron oscillation model.
126297547
Experimental study of hadron inclusive production in J / psi energy region
119106910
Detection of 107 glitches in 36 southern pulsars
Timing observations from the Parkes 64-m radio telescope for 165 pulsarsbetween 1990 and 2011 have been searched for period glitches. Data spansfor each pulsar ranged between 5.3 and 20.8 yr. From the total of 1911yr of pulsar rotational history, 107 glitches were identified in 36pulsars. Out of these glitches, 61 have previously been reported whereas46 are new discoveries. Glitch parameters, both for the previously knownand the new glitch detections, were measured by fitting the timingresidual data. Observed relative glitch sizes{$\Delta$}{$\nu$}$_{g}$/{$\nu$} range between 10$^{-10}$ and10$^{-5}$, where {$\nu$} = 1/P is the pulse frequency. We confirmthat the distribution of {$\Delta$}{$\nu$}$_{g}$/{$\nu$} is bimodal withpeaks at approximately 10$^{-9}$ and 10$^{-6}$. Glitches aremostly observed in pulsars with characteristic ages between10$^{3}$ and 10$^{5}$ yr, with large glitches mostlyoccurring in the younger pulsars. Exponential post-glitch recoverieswere observed for 27 large glitches in 18 pulsars. The fraction Q of theglitch that recovers exponentially also has a bimodal distribution.Large glitches generally have low Q, typically just a few per cent, butlarge Q values are observed in both large and small glitches. Observedtime constants for exponential recoveries ranged between 10 and 300 dwith some tendency for longer time-scales in older pulsars. Shortertime-scale recoveries may exist but were not revealed by our data whichtypically have observation intervals of 2-4 weeks. For most of the 36pulsars with observed glitches, there is a persistent linear increase indot$\{${$\nu$} $\}$ (i.e. decrease in the slow-down rate |dot$\{${$\nu$} $\}$|) in theinterglitch interval. Where an exponential recovery is also observed,the effects of this are superimposed on the linear increase in dot$\{${$\nu$}$\}$. In some but not all cases, the slope of the linear recovery changesat the time of a glitch. The ddot$\{${$\nu$} $\}$ values characterizing thelinear changes in dot$\{${$\nu$} $\}$ are almost always positive and, aftersubtracting the magnetospheric component of the braking, areapproximately proportional to the ratio of |dot$\{${$\nu$} $\}$| and theinterglitch interval, as predicted by vortex-creep models.
5912215
A Strange Star Model for Pulsars
It is suggested in this paper that the `bare' strange star might be not bare, and there could be a magnetosphere around it. As a strange star might be an intensely magnetized rotator, the induced unipolar electric field would be large enough to construct a magnetosphere around the strange matter core. 
This kind of magnetosphere is very similar to that of the rotating magnetized neutron stars discussed by many authors. A magnetosphere will be established very soon through pair production by gamma-B or two photon processes after a strange star was born in a supernova explosion. It is emphasized that the fact that the strange star surface can not supply charged particles does not stop the formation of a space charge separated magnetosphere around the bare strange star. An accretion crust is quite difficult to come into being around an isolated strange star. Therefore the observed radio signals of an rotation-powered pulsar may come from a bare strange stars rather than a neutron stars or a strange star with an accretion crust. The idea, that the radio pulsars are the strange stars without crusts, is supported by some observations. The fact, that the iron emission lines have been observed in many X-ray pulsars but never been reported in X-ray emission of radio pulsars, is difficult to be understood if the radio pulsars are the neutron stars or strange star with crust where the surface binding energy of iron ions is too low to avoid a ion free-flow from the surface.