We present here a set of examples, classes and tools which can be used for statistical analysis in Graphics Processing Units (GPU). This includes binned and unbinned maximum likelihood fits, ...pseudo-experiment generation, convolutions, Markov Chain Monte Carlo method implementations, and limit setting techniques.
We search for CP violation in neutral charm meson decays using a data sample with an integrated luminosity of 966 fb–1 collected with the Belle detector at the KEKB e+e– asymmetric-energy collider. ...The asymmetry obtained in the rate of D0 and D0¯ decays to the π0π0 final state, –0.03±0.64(stat)±0.10(syst)%, is consistent with no CP violation. This constitutes an order of magnitude improvement over the existing result. Here, we also present an updated measurement of the CP asymmetry in the D0→K$^{0}_{S}$π0 decay: ACP(D0 → K$^{0}_{S}$π0) = –0.21±0.16(stat)±0.07(syst)%.
The e+e– → π+π–π0χbJ (J = 0,1,2) processes are studied using a 118 fb–1 data sample acquired with the Belle detector at a center-of-mass energy of 10.867 GeV. Unambiguous π+π–π0χbJ (J = 1,2), ωχb1 ...signals are observed, and indication for ωχb2 is seen, both for the first time, and the corresponding cross section measurements are presented. No significant π+π–π0χb0 or ωχb0 signals are observed, and 90% confidence level upper limits on the cross sections for these two processes are obtained. In the π+π–π0 invariant mass spectrum, significant non-ω signals are also observed. In conclusion, we search for the X(3872)-like state (named Xb) decaying into ωΥ(1S); no significant signal is observed with a mass between 10.55 and 10.65 GeV/c2.
In this work, we observe D0- D ¯ 0 mixing in the decay D0 → K+π- using a data sample of integrated luminosity 976 fb-1 collected with the Belle detector at the KEKB e+e- asymmetric-energy collider. ...We measure the mixing parameters x'2= ( 0.09±0.22 ) ×10-3 and y'= ( 4.6±3.4 ) ×10-3 and the ratio of doubly Cabibbo-suppressed to Cabibbo-favored decay rates RD= ( 3.53±0.13 ) ×10-3 , where the uncertainties are statistical and systematic combined. Our measurement excludes the no-mixing hypothesis at the 5.1 standard deviation level.
We present the recent measurements of the B0 -> eta' K0 and the B -> omega K decay modes based on the full data set of 772x10^6 BBbar pairs collected by the Belle detector at the KEKB e+e- collider. ...In the B0 -> eta' K^{0} mode, we obtain the CP-violating parameters A(eta'K0) = +0.03+/-0.05(stat)+/-0.04(syst), S(eta'K0) = +0.68+/-0.07(stat)+/-0.03(syst). This is the world's most precise result on the eta' K0 CP parameters. In B -> omega K decays, we measure the branching fractions B(B0 -> omega K0) = (4.5+/-0.4(stat)+/-0.3(syst))x10^-6, B(B- -> omega K-) = (6.8+/-0.4(stat)+/-0.4(syst))x10^-6, which are their current most precise results. We measure the first evidence of CP violation in the B0 -> omega K0S decay mode, obtaining the CP-violating parameters A(omega K0S} = -0.36+/-0.19(stat)+/-0.05(syst), S(omega K0S} = +0.91+/-0.32(stat)+/-0.05(syst). In the B- -> omega K- mode, we measure the direct CP-violation parameter A(omega K-) = -0.03+/-0.04(stat)+/-0.01(syst), which is its most precise measurement to date.
We search for bottomonium states in $\Upsilon(2S)$ → ($\bar{bb}$) gamma decays with an integrated luminosity of 24.7fb-1 recorded at the $\Upsilon(2S)$ resonance with the Belle detector at KEK, ...containing (157.8 ± 3.6) X 106 $\Upsilon(2S)$ events. The ($\bar{bb}$) system is reconstructed in 26 exclusive hadronic final states composed of charged pions, kaons, protons, and $K^0_S$ mesons. We find no evidence for the state recently observed around 9975 MeV ($X_{\bar{bb}}$) in an analysis based on a data sample of 9.3 X 106 $\Upsilon(2S)$ events collected with the CLEO III detector. We set a 90 % confidence-level upper limit on the branching fraction $Β$$\Upsilon(2S)$ → $X_{\bar{bb}\gamma}$ X $\sum_i$ $B$$X_{\bar{bb}}$ → $h_i$ $<$ 4.9 X 10-6, summed over the exclusive hadronic final states employed in our analysis. This result is an order of magnitude smaller than the measurement reported with CLEO data. We also set an upper limit for the $\eta_b(1S)$ state of $B$$\Upsilon(2S)$ → $\eta_b(1S)\gamma$ X $\sum_i$B$\eta_b(1S)$ → $h_i$ $<$ 3.7 X 10-6.
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