Type

Database

Creator

Date

Thumbnail

Search results

1,095 records were found.

The SuperB project is an asymmetric e(+)e(-) accelerator of 10(36)cm(-2)s(-1) luminosity, capable of collecting a 50 - 75 ab(-1) data sample in five years of running. The SuperB electromagnetic calorimeter (EMC) provides energy and direction measurement of photons and electrons and identification versus other charged particles for electrons. A matrix of 25 LYSO crystals has been tested at the Beam Test Facility at Frascati in May 2011 at energies between 100 MeV and 500 MeV. Results from this test will be presented. Design and Monte Carlo studies for the general EMC system will also be presented.
This report describes the present status of the detector design for SuperB. It is one of four separate progress reports that, taken collectively, describe progress made on the SuperB Project since the publication of the SuperB Conceptual Design Report in 2007 and the Proceedings of SuperB Workshop VI in Valencia in 2008. The other three reports relate to Physics, Accelerator and Computing.
A study of neutral-current four-fermion processes is performed, using data collected by the L3 detector at LEP during high-energy runs at centre-of-mass energies 130 - 136, 161 and 170 - 172 GeV, with integrated luminosities of 4.9, 10.7 and 10.1 pb$^{-1}$, respectively. The total cross sections for the final states $ \ell\ell \ell^\prime \ell^\prime $ and $\rm \ell\ell qq $ ($\ell$,~$\ell^\prime $ = e, $\mu$ or $\tau$) are measured and found to be in agreement with the Standard Model prediction.
We present a study of the inclusive $\omega$ and $\eta^{\prime}$ production based on 3.1 million hadronic Z decays recorded with the L3 detector at LEP during 1991--1994. The production rates per hadronic Z decay have been measured to be $1.17 \pm 0.17 $ $\omega$ mesons and $0.25 \pm 0.04 $ $\eta^{\prime}$ mesons. The production rates and the differential cross sections have been compared with predictions of the JETSET and the HERWIG Monte Carlo models. We have observed that the differential cross sections can be described by an analytical quantum chromodynamics calculation. \end{document}
We present a measurement of the average b-hadron lifetime ${\rm \tau_b}$ at the $\mathrm{e^+e^-} \, $ collider LEP. Using hadronic Z decays collected in the period from 1991 to 1994, two independent analyses have been performed. In the first one, the b-decay position is reconstructed as a secondary vertex of hadronic b-decay particles. The second analysis is an updated measurement of ${\rm \tau_b}$ using the impact parameter of leptons with high momentum and high transverse momentum. The combined result is \begin{center} ${\rm \tau_b= [ 1549 \pm 9 \, (stat) \, \pm 15 \, (syst) ] \; fs \,}$ . \end{center} In addition, we measure the average charged b-decay multiplicity ${\rm \langle n_{\rm b}} \rangle$ and the normalized average b-energy ${\rm \langle x_E \rangle_{\rm b}}$ at LEP to be \begin{center} ${\rm \langle n_{\rm b} \rangle = 4....
The measurements of hadron and lepton--pair production cross sections and lepton--pair forward--backward asymmetries performed with the L3 detector at centre--of--mass energies between 130 GeV and 172 GeV are used to search for new physics phenomena. New physics effects involving four fermion vertices -- contact interactions -- are looked for in all channels. For hadron production the exchange of virtual leptoquarks and scalar quarks is studied. No evidence for deviations from the Standard Model expectations is found. Lower limits on the scale $\Lambda$ of contact interactions in the range 1.2 -- 7.1 TeV are obtained at the 95\% confidence level for various models. Upper limits on the coupling strengths of leptoquarks and scalar quarks are derived.
The reaction $\mathrm{e}^{+} \mathrm{e}^{-} \rightarrow \mathrm{e}^{+} \mathrm{e}^{-} \gamma ^{*} \gamma ^{*} \rightarrow \mathrm{e}^{+} \mathrm{e}^{-} $ {\sl hadrons} is analysed using data collected by the L3 detector during the LEP runs at $\sqrt {s}$ = 130-140 GeV and $\sqrt {s}$ = 161 GeV. The cross sections $\sigma(\mathrm{e}^{+} \mathrm{e}^{-} \rightarrow \mathrm{e}^{+} \mathrm{e}^{-} $ {\sl hadrons}) and $\sigma (\gamma\gamma \rightarrow $ {\sl hadrons}) are measured in the interval 5 $\leq W_{\gamma\gamma} \leq$ 75 GeV. The energy dependence of the $\sigma (\gamma\gamma \rightarrow $ {\sl hadrons}) cross section is consistent with the universal Regge behaviour of total hadronic cross sections. %\end{abstract}
We report on the observation of single W boson production in a data sample collected by the L3 detector at LEP2. The signal consists of large missing energy final states with a single energetic lepton or two hadronic jets. The cross-section is measured to be $0.61^{+0.43}_{-0.33} \pm 0.05 \; \rm{pb}$ at the centre of mass energy $\sqrt{s}=172 \GeV{}$, consistent with the Standard Model expectation. From this measurement the following limits on the anomalous $\gamma$WW gauge couplings are derived at 95\% CL: $\rm -3.6 \Delta \kappa_\gamma 1.5$ and $\rm -3.6 \lambda_\gamma 3.6$.
An analysis of single and multi-photon events with missing energy is performed using data collected with the L3 detector at LEP at centre-of-mass energies around 183\gev, for a total of 55.3 pb$^{-1}$ of integrated luminosity. The results obtained are in good agreement with the Standard Model prediction and are used to derive the value for the $\epem\ra\nnbar\gamma(\gamma)$ cross section as well as upper limits on cross sections of new physics processes. Several interpretations in supersymmetric models providing new limits on the masses of the lightest neutralino and of the gravitino are presented.
Want to know more?If you want to know more about this cutting edge product, or schedule a demonstration on your own organisation, please feel free to contact us or read the available documentation at http://www.keep.pt/produtos/retrievo/?lang=en