Внедрение и принцип работы системы сейсмического мониторинга горного массива для работы в условиях ООО "Шахта "Усковская"

The status of the Silicon Microvertex Detector (SMD) and its installation into the LEP-L3 experiment are presented, highlighting novel features and sophisticated techniques. Preliminary results based on 1993 data are given and compared with Monte Carlo predictions, to understand the detector performances and its tracking capabilities

Determination of the number of light neutrino species from single photon production at LEP

A determination of the number of light neutrino families performed by measuring the cross section of single photon production in \ee\ collision near the \Zo\ resonance is reported. From an integrated luminosity of $100~\mathrm{pb^{-1}}$, collected during the years 1991--94, we have observed 2091 single photon candidates with an energy above 1~\GeV\ in the polar angular region $45^\circ < \theta_\gamma < 135^\circ$. From a maximum likelihood fit to the single photon cross section, the \Zo\ decay width into invisible particles is measured to be \Ginv = 498 \pm 12 \mathrm{(stat)} \pm 12 \mathrm{(sys)~MeV}. Using the Standard Model couplings of neutrinos to the \Zo, the number of light neutrino species is determined to be $N_\nu = 2.98 \pm 0.07 (\mathrm{stat}) \pm 0.07 (\mathrm{sys}).

Search for R-Parity Breaking Sneutrino Exchange at LEP

We report on a search for R--parity breaking effects due to supersymmetric tau--sneutrino exchange in the reactions e+e- to e+e- and e+e- to mu+mu- at centre--of--mass energies from 91~{\GeV} to 172~{\GeV}, using the L3 detector at LEP. No evidence for deviations from the Standard Model expectations of the measured cross sections and forward--backward asymmetries for these reactions is found. Upper limits for the couplings $\lambda_{131}$ and $\lambda_{232}$ for sneutrino masses up to m_{\SNT} \leq 190~\GeV are determined from an analysis of the expected effects due to tau sneutrino exchange

Search for neutral B meson decays to two charged leptons

The decays $\mathrm{B_d^0,\,B_s^0 \rightarrow e^+e^-,\,\mu^+\mu^-,\, e^\pm\mu^\mp}$ are searched for in 3.5 million hadronic ${\mathrm{Z}}$ events, which constitute the full LEP I data sample collected by the L3 detector. No signals are observed, therefore upper limits at the 90\%(95\%) confidence levels are set on the following branching fractions: % \begin{center}% {\setlength{\tabcolsep}{2pt} \begin{tabular}{lccccclcccc}% % Br$({\mathrm{B_d^0 \rightarrow {\mathrm{e^+e^-}}}})$ & $<$ & $1.4(1.8)$ & $\times$ & $10^{-5}$; & \hspace*{5mm} & Br$({\mathrm{B_s^0 \rightarrow {\mathrm{e^+e^-}}}})$ & $<$ & $5.4(7.0)$ & $\times$ & $10^{-5}$; \\% Br$({\mathrm{B_d^0 \rightarrow \mu^+\mu^-}})$ & $<$ & $1.0(1.4)$ & $\times$ & $10^{-5}$; & \hspace*{5mm} & Br$({\mathrm{B_s^0 \rightarrow \mu^+\mu^-}})$ & $<$ & $3.8(5.1)$ & $\times$ & $10^{-5}$; \\% Br$({\mathrm{B_d^0 \rightarrow {\mathrm{e^\pm\mu^\mp}}}})$ & $<$ & $1.6(2.0)$ & $\times$ & $10^{-5}$; & \hspace*{5mm} & Br$({\mathrm{B_s^0 \rightarrow {\mathrm{e^\pm\mu^\mp}}}})$ & $<$ & $4.1(5.3)$ & $\times$ & $10^{-5}$. \\% % \end{tabular}% } \end{center}% % The results for ${\mathrm{B_s^0\rightarrow{\mathrm{e^+e^-}}}}$ and ${\mathrm{B_s^0 \rightarrow {\mathrm{e^\pm\mu^\mp}}}}$ are the first limits set on these decay modes

Local multiplicity fluctuations in hadronic Z decay

Local multiplicity fluctuations in hadronic Z decays are studied using the L3 detector at LEP. Bunching parameters are used for the first time in addition to the normalised factorial moment method. The bunching parameters directly demonstrate that the fluctuations in rapidity are multifractal. Monte Carlo models show overall agreement with the data, reproducing the trend, although not always the magnitude, of the factorial moments and bunching parameters

Angular multiplicity fluctuations in hadronic Z decays and comparison to QCD models and analytical calculations

Local multiplicity fluctuations in angular phase space intervals are studied using factorial moments measured in hadronic events at \sqrt{s}\simeq 91.2\GeV, which were collected by the L3 detector at LEP in 1994. Parton shower Monte Carlo programs agree well with the data. On the other hand, first-order QCD calculations in the Double Leading Log Approximation and the Modified Leading Log Approximation are found to deviate significantly from the data

Study of the Weak Charged Hadronic Current in b Decays

Charged and neutral particle multiplicities of jets associated with identified semileptonic and hadronic b decays are studied. The observed differences between these jets are used to determine the inclusive properties of the weak charged hadronic current. The average charged particle multiplicity of the weak charged hadronic current in b decays is measured for the first time to be 2.69$\pm$0.07(stat.)$\pm$0.14(syst.). This result is in good agreement with the JETSET hadronization model of the weak charged hadronic current if 40$\pm$17\% of the produced mesons are light--flavored tensor (L=1) mesons. This level of tensor meson production is consistent with the measurement of the $\pi^0$ multiplicity in the weak charged hadronic current in b decays. \end{abstract