Hybrid Quantum Singular Spectrum Decomposition for Time Series Analysis

Classical data analysis requires computational efforts that become intractable in the age of Big Data. An essential task in time series analysis is the extraction of physically meaningful information from a noisy time series. One algorithm devised for this very purpose is singular spectrum decomposition (SSD), an adaptive method that allows for the extraction of narrow-banded components from non-stationary and non-linear time series. The main computational bottleneck of this algorithm is the singular value decomposition (SVD). Quantum computing could facilitate a speedup in this domain through superior scaling laws. We propose quantum SSD by assigning the SVD subroutine to a quantum computer. The viability for implementation and performance of this hybrid algorithm on a near term hybrid quantum computer is investigated. In this work we show that by employing randomised SVD, we can impose a qubit limit on one of the circuits to improve scalibility. Using this, we efficiently perform quantum SSD on simulations of local field potentials recorded in brain tissue, as well as GW150914, the first detected gravitational wave event.Comment: 18 pages, 6 figure

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

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

Tests Qed at Lep Energies Using E(+)E(-)-]Gamma-Gamma(Gamma) and E(+)E(-)-]L(+)L(-)Gamma-Gamma

Contains fulltext : 28970.pdf (preprint version ) (Open Access

Measurement of the branching ratios b -> e nu Chi, mu nu Chi, tau nu Chi, and nu Chi

Contains fulltext : 26243.pdf (publisher's version ) (Open Access

Measurement of η\eta production in two and three-jet events from hadronic Z decays at LEP

The inclusive production of \eta mesons has been studied using 1.6 million hadronic Z decays collected with the L3 detector. The \eta multiplicity per event, the multiplicity for two-jet and three-jet events separately, and the multiplicity in each jet have been measured and compared with the predictions of different Monte Carlo programs. The momentum spectra of \eta in each jet have also been measured. We observe that the measured \eta momentum spectrum in quark-enriched jets agrees well with the Monte Carlo prediction while in gluon-enriched jets it is harder than that predicted by the Monte Carlo models

Search for excited leptons in e+e−e^{+} e^{-} annihilation at s\sqrt {s} = 130 - 140 GeV

We report on a search for the excited leptons e^*,mu^*,tau^* and nu^* in e+e- collisions at sqrt{s} = 130 - 140 GeV using the L3 detector at LEP. No evidence has been found for their existence. From an analysis of the expected pair produced l^*l^* in the channels e.e.gamma.gamma, mu.mu.gamma.gamma, tau.tau.gamma.gamma, eeWW, and nu.nu.gamma.gamma, we determine the lower mass limits at 95% C.L. of 64.7 GeV for e^*, 64.9 GeV for mu^*, 64.2 GeV for tau*, 57.3 GeV ( eW decay mode) and 61.4 GeV ( nu.gamma decay mode) for nu^*. From an analysis of the expected singly produced l.l^* in the channels e.e.gamma, mu.mu.gamma, tau.tau.gamma, nu.eW and nu.nu.gamma, we determine upper limits on the couplings lambda/m_{l^*} up to m_{l^*} = 130 GeV

Search for Exclusive B Decays to J and η\eta or π0\pi^{0} with the L3 Detector

A search for exclusive decays of \ensuremath{\mathrm{B_d^0}} and \ensuremath{\mathrm{B_s^0}} mesons has been performed in the channels \ensuremath{\mathrm{B_d^0}\rightarrow\mathrm{J}\eta},\,\, \ensuremath{\mathrm{B_s^0}\rightarrow\mathrm{J}\eta},\,\, \ensuremath{\mathrm{B_d^0}\rightarrow\mathrm{J}\pi^0} and \ensuremath{\mathrm{B_s^0}\rightarrow\mathrm{J}\pi^0}. The data sample consisted of more than three and half million hadronic \ensuremath{\mathrm {Z}} decays collected by the L3 experiment at LEP from 1991 through 1995. No candidate events have been observed for any of the modes thus determining upper limits at 90\% confidence level: $3.2\times 10^{-4}$ on \mathrm{Br}(\ensuremath{\mathrm{B_d^0}\ rightarrow\mathrm{J}\pi^0)} and the first experimental limits: \begin{eqnarray*} \mathrm{Br}(\ensuremath{\mathrm{B_d^0}\rightarrow \mathrm{J}\eta}) & < & 1.2\times 10^{-3},\\ \mathrm{Br}(\ensuremath{\m athrm{B_s^0}\rightarrow\mathrm{J}\eta}) & < & 3.8\times 10^{-3},\\ \mathrm{Br}(\ensuremath{\mathrm{B_s^0}\rightarrow\mathrm {J}\pi^0}) & < & 1.2\times 10^{-3}.\\ \end{eqnarray*