Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Single- and multi-photon production in ee collisions at $\sqrt{s}$ up to 209 GeV (2003)
    Springer
    The European physical journal 28 (2003), S. 1-13 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Events containing only energetic photons are analysed in a sample of $628 \mathrm{pb}^{-1}$ of data recorded from $\rm e^+e^-$ collisions at centre-of-mass energies between 189 and 209 GeV by the ALEPH detector at LEP. The $e^+ e^-\to \nu\bar{\nu}\gamma(\gamma)$ and $e^+ e^-\to \gamma\gamma(\gamma)$ cross sections are measured and found to be in agreement with the standard model predictions. The number of light neutrino generations is determined to be $N_\nu = 2.86 \pm 0.09$ . Upper limits are derived on the cross sections for photon production in the context of several supersymmetric models. Limits are also set on the parameters of models with extra spatial dimensions, with contact interactions and with excited electrons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1140/epjc/s2002-01129-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Inclusive semileptonic branching ratios of b hadrons produced in Z decays (2002)
    Springer
    The European physical journal 22 (2002), S. 613-626 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. A measurement of the inclusive semileptonic branching ratios of b hadrons produced in Z decay is presented, using four million hadronic events collected by the ALEPH detector from 1991 to 1995. Electrons and muons are selected opposite to b-tagged hemispheres. Two different methods are explored to distinguish the contributions from direct ${{\mathrm b}\to{\mathrm{X}}\ell \nu}$ and cascade ${{\mathrm b}\to{\mathrm c}\to{\mathrm X} \ell \nu}$ decays to the total lepton yield. One is based on the lepton transverse momentum spectrum, the other makes use of the correlation between the charge of the lepton and charge estimators built from tracks in the opposite hemisphere of the event. The latter method reduces the dependence on the modelling of semileptonic b decays. The results obtained by averaging the two techniques are \begin{eqnarray} {\mathrm{BR}}({\mathrm b}\to{\mathrm{X}} \ell \nu)& = & 0.1070 \pm 0.0010 _{\mathrm{stat}} \pm 0.0023 _{\mathrm{syst}} \pm 0.0026 _{\mathrm{model}} , \nonumber {\mathrm{BR}}({\mathrm b}\to{\mathrm c}\to{\mathrm X} \ell \nu)& = & 0.0818 \pm 0.0015 _{\mathrm{stat}} \pm 0.0022 _{\mathrm{syst}} {^{+0.0010} _{-0.0014}} _{\mathrm{model}} . \nonumber \end{eqnarray}
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100520100851
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Measurement of the Tau Polarisation at LEP (2001)
    Springer
    The European physical journal 20 (2001), S. 401-430 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The polarisation of $\tau$ 's produced in Z decay is measured using 160 pb $^{-1}$ of data accumulated at LEP by the ALEPH detector between 1990 and 1995. The variation of the polarisation with polar angle yields the two parameters ${\cal A}_e = 0.1504 \pm 0.0068 $ and ${\cal A}_{\tau} = 0.1451 \pm 0.0059$ which are consistent with the hypothesis of e- $\tau$ universality. Assuming universality, the value ${\cal A}_{e\mbox{-}\tau} = 0.1474 \pm 0.0045$ is obtained from which the effective weak mixing angle $\sin^2{\theta_{\mathrm{W}}^{\mathrm{eff}}} =0.23147 \pm 0.00057 $ is derived.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100520100689
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Measurement of triple gauge-boson couplings at LEP energies up to 189 GeV (2001)
    Springer
    The European physical journal 21 (2001), S. 423-441 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. The triple gauge-boson couplings involving the W are determined using data samples collected with the ALEPH detector at mean centre-of-mass energies of 183 GeV and 189 GeV, corresponding to integrated luminosities of 57 pb $^{-1}$ and 174 pb $^{-1}$ , respectively. The couplings, $g^Z_1$ , $\kappa_\gamma$ and $\lambda_\gamma$ , are measured using W-pair events, single-{\it W} production and single- $\gamma$ production. Each coupling is measured individually with the other two couplings fixed at their standard model value. Including ALEPH results from lower energies, the 95% confidence level intervals for the deviation to the standard model are $-0.087 〈\Delta{g}^{Z}_1 〈 0.141$ , $-0.200 〈 \Delta\kappa_\gamma 〈 0.258$ , and $-0.062 〈 \lambda_\gamma 〈 0.147$ . Fits are also presented where two or all three couplings are allowed to vary. In addition, W-pair events are used to set limits on the C- or P-violating couplings $g^V_4$ , $g^V_5$ , ${\tilde{\kappa}_{V}}$ , and ${\tilde{\lambda}_{V}}$ , where V denotes either $\gamma$ or Z. No deviations from the standard model expectations are observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100520100730
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Measurement of the Michel parameters and the $\nu_\tau$ helicity in $\tau$ lepton decays (2001)
    Springer
    The European physical journal 22 (2001), S. 217-230 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. A measurement of the Michel parameters and the average $\nu_\tau$ helicity in $\tau$ lepton decays is described. The data was collected with the ALEPH detector at LEP during the years 1991 to 1995. A total integrated luminosity of 155 $\text{pb}^{-1}$ is analysed. The Michel parameters $\rho_l, \xi_l, (\xi\delta)_l (l=e,\mu)$ , and $\eta_\mu$ are determined for the leptonic decays, and the chirality parameters $\xi_\pi, \xi_\rho$ , and $\xi_{a_1}$ for the hadronic final states. Under the assumptions of e- $\mu$ universality and $\xi_\pi=\xi_\rho=\xi_{a_1}$ , the values $\rho_l=0.742\pm 0.016, \eta_l=0.012\pm 0.026, (\xi\delta)_l=0.776\pm 0.051,\xi_l=0.986\pm0.074$ , and $\xi_h=0.992\pm 0.011$ are obtained. No significant deviation is observed from the Standard Model assumption of the V-A structure of the charged weak interaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100520100813
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Measurement of $A_{\rm FB}^b$ using inclusive $b$ -hadron decays (2001)
    Springer
    The European physical journal 22 (2001), S. 201-215 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Based on a sample of four million events collected by ALEPH from 1991 to 1995, a measurement of the forward-backward asymmetry in $Z \rightarrow b\bar{b}$ decays using inclusive final states is presented. High-performance tagging of $b\bar{b}$ events in a wide angular range is achieved using neural network techniques. An optimal hemisphere charge estimator is built by merging primary and secondary vertex information, leading kaon identification and jet charge in a neural network. The average charge asymmetry, the flavour tagging efficiencies and mean b-hemisphere charges are measured from data and used to extract the pole b asymmetry in the Standard Model \begin{eqnarray*} \nonumber A^{0,b}_{\rm FB} & = & 0.1011 \, \pm \,0.0027\,(stat) \,\pm \,0.0012\,(syst)\,, \end{eqnarray*} corresponding to a value of the effective weak mixing angle of \[ {\rm sin^2} \theta_{\rm W}^{\rm eff} = 0.23189 \pm 0.00056\,. \]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100520100812
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Search for R-parity violating production of single sneutrinos in ee collisions at $\sqrt{s}$ = 189-209 GeV (2002)
    Springer
    The European physical journal 25 (2002), S. 1-12 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. A search for single sneutrino production under the assumption that R-parity is violated via a single dominant $LL\bar{E}$ coupling is presented. This search considers the process ${\rm e} \gamma \rightarrow \tilde{\nu}\ell$ and is performed using the data collected by the ALEPH detector at centre-of-mass energies from 189 GeV up to 209 GeV corresponding to an integrated luminosity of 637.1 pb-1. The numbers of observed candidate events are in agreement with Standard Model expectations and 95% confidence level upper limits on five of the $LL\bar{E}$ couplings are given as a function of the assumed sneutrino mass.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s10052-002-1010-2
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Search for gauge mediated SUSY breaking topologies in ee collisions at centre-of-mass energies up to 209 GeV (2002)
    Springer
    The European physical journal 25 (2002), S. 339-351 
    Details
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. A total of 628 bp-1 of data collected with the ALEPH detector at centre-of-mass energies from 189 to 209 GeV is analysed in the search for gauge mediated SUSY breaking (GMSB) topologies. These topologies include two acoplanar photons, non-pointing single photons, acoplanar leptons, large impact parameter leptons, detached slepton decay vertices, heavy stable charged sleptons and multi-leptons plus missing energy final states. No evidence is found for new phenomena, and lower limits on masses of supersymmetric particles are derived. A scan of a minimal GMSB parameter space is performed and lower limits are set for the next-to-lightest supersymmetric particle (NLSP) mass at 54 GeV/c2 and for the mass scale parameter $\Lambda$ at 10 TeV/c2, independently of the NLSP lifetime. Including the results from the neutral Higgs boson searches, a NLSP mass limit of 77 GeV/c2 is obtained and values of $\Lambda$ up to 16 TeV/c2 are excluded.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s10052-002-1005-z
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...