James Frederick Libby

Equation (5) contained an error; the correct expression is: (5) Yi=HK3π(Ki+(rDK3π)2K−i−2rDK3πKiK−iRK3π[cicos⁡δDK3π−sisin⁡δDK3π]). This correction leads to changes in the results and associated correlations for the fit to the CLEO-c observables reported in Tables 6 and 7, respectively. The reduced χ2 of this fit is 29.5/33. Changes are also observed in the Δχ2 scans presented in Fig. 3. When performing an updated global fit to the CLEO-c and LHCb observables a reduced χ2 of 33.5/36 is obtained. Changes occur to the values reported in Tables 9 and 10, and the scans presented in Fig. 5. In addition a typographical error was introduced into Eq. (1). The correct expression is(1)RK3πe−iδDK3π=∫AK−π+π+π−⁎(x)AK+π−π+π−(x)dxAK−π+π+π−AK+π−π+π−. The results presented in the paper are unaffected by this error.

We report results on studies of the e+e-annihilation into three-body (nS)π+π-(n=1,2,3) final states including measurements of cross sections and the full amplitude analysis. The cross sections measured at s=10.866GeV and corrected for the initial state radiation are σ(e+e-→ (1S)π+π-)=(2.27±0.12±0.14)pb, σ(e+e-→ (2S)π+π-)=(4.07±0.16±0.45)pb, and σ(e+e-→ (3S)π+π-)=(1.46±0.09±0.16)pb. Amplitude analysis of the three-body (nS)π+π-final states strongly favors IG(JP)=1+(1+) quantum-number assignments for the two bottomonium-like Zb± states, recently observed in the (nS)π± and hb(mP)π± (m=1,2) decay channels. The results are obtained with a 121.4fb-1 data sample collected with the Belle detector at the KEKB asymmetric-energy e+e-collider.

The Belle II experiment, which is situated at the interaction point of the SuperKEKB e+e− collider at KEK, Tsukuba, Japan, is expected to collect data corresponding to an integrated luminosity of 50 ab−1. This data set will be sensitive to beyond-the-standard-model physics via precision measurements and searches for very rare decays. At its heart lies a six-layer vertex detector consisting of two layers of pixel detectors (PXD) and four layers of double-sided silicon microstrip detectors (SVD). Precise vertexing as provided by this device is essential for measurements of time-dependent CP violation. Crucial aspects of the SVD assembly are precise alignment, as well as rigorous electrical and geometrical quality assurance. We present an overview of the construction of the SVD, including the precision gluing of SVD component modules and the wire-bonding of various electrical components. We also discuss the electrical and geometrical quality assurance tests.

In 2019 the Belle II experiment started data taking at the asymmetric SuperKEKB collider (KEK, Japan) operating at the Y(4S) resonance. Belle II will search for new physics beyond the standard model by collecting an integrated luminosity of 50 ab−1. The silicon vertex detector (SVD), consisting of four layers of double-sided silicon strip sensors, is one of the two vertex sub-detectors. The SVD extrapolates the tracks to the inner pixel detector (PXD) with enough precision to correctly identify hits in the PXD belonging to the track. In addition the SVD has standalone tracking capability and utilizes ionization to enhance particle identification in the low momentum region. The SVD is operating reliably and with high efficiency, despite exposure to the harsh beam background of the highest peak-luminosity collider ever built. High signal-to-noise ratio and hit efficiency have been measured, as well as the spatial resolution; all these quantities show excellent stability over time. Data-simulation agreement on cluster properties has recently been improved through a careful tuning of the simulation. The precise hit-time resolution can be exploited to reject out-of-time hits induced by beam background, which will make the SVD more robust against higher levels of background. During the first three years of running, radiation damage effects on strip noise, sensor currents and depletion voltage have been observed, as well as some coupling capacitor failure due to intense radiation bursts. None of these effects cause significant degradation in the detector performance.

This paper shows the hardware and the procedure utilized to test all components of the readout system (cables, FADC boards, junction boards) of the Belle II Silicon Vertex Detector after the series production. For the FADC board special testing hardware and firmware were designed and created to check all digital and analog inputs and outputs as well as all data interconnections on the board. The main FPGA on the FADC board generates digital signals which are converted to periodic analog differential alternating voltages up to 40 MHz on the FADC board tester, which then are fed into the analog inputs of the FADC board. Histograms and scans of the samples are recorded by using random equivalent-time sampling or sequential equivalent-time sampling, allowing to characterize the behavior of the system with a much higher bandwidth than the ADCs could do with conventional measurements. Small changes of parameters of the assembly (like using a cable of different length) lead to significant changes of the measured values, creating a sensitive testing instrument. The shapes of the distributions are analyzed and compared to references by software which then decides if a test is passed or not. The commissioning setup of the whole readout chain, with all the final components including the final detector, has been tested in three phases. The respective graphs of the signal-to-noise ratios of the strips of a detector module and histograms of the noise development of the whole detector show very high consistency of the SVD readout system.

We report the first observation of the double strange baryon Ξ(1620)0 in its decay to Ξ-π+ via Ξc+→Ξ-π+π+ decays based on a 980 fb-1 data sample collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. The mass and width are measured to be 1610.4±6.0(stat)-4.2+6.1 (syst) MeV/c2 and 59.9±4.8(stat)-7.1+2.8(syst) MeV, respectively. We obtain 4.0σ evidence of the Ξ(1690)0 with the same data sample. These results shed light on the structure of hyperon resonances with strangeness S=-2.

We report on a study of exclusive radiative decays of the Υ(1S) resonance into a final state consisting of a photon and two KS0 candidates. We find evidence for a signal for Υ(1S)→γf2′(1525); f2′(1525)→γKS0KS0, at a rate B(Υ(1S) →γf2′(1525))=(4.0±1.3±0.6)×10-5, consistent with previous observations of Υ(1S)→γf2′(1525) ; f2′(1525)→K+K-, and isospin. Combining this branching fraction with existing branching fraction measurements of Υ(1S)→γf2′(1525) and J/ψ→γf2′(1525), we obtain the ratio of branching fractions: B(Υ(1S) →γf2′(1525))/B(J/ψ→γf2′(1525))=0. 09±0.02, approximately consistent with expectations based on soft-collinear effective theory. © 2011 American Physical Society.

At the High Energy Accelerator Research Organization (KEK) in Tsukuba, Japan, the double-sided silicon strip sub-detector of the Belle II experiment is read out by 1748 APV25 chips. FPGAs perform several calculations on the digitized signals. One of them will be "Hit Time Finding": the determination of the time and amplitude of the signal peaks of each event in real time using pre-programmed neural networks. This work analyses the possibility, precision and reliability of these calculations depending on various parameters.

Using a data sample of 980 fb−1 collected with the Belle detector at the KEKB asymmetric-energy e+e− collider, we study the processes of Ξc0→ΛK¯∗0, Ξc0→Σ0K¯∗0, and Ξc0→Σ+K∗− for the first time. The relative branching ratios to the normalization mode of Ξc0→Ξ−π+ are measured to beB(Ξc0→ΛK¯∗0)/B(Ξc0→Ξ−π+)=0.18±0.02(stat.)±0.01(syst.),B(Ξc0→Σ0K¯∗0)/B(Ξc0→Ξ−π+)=0.69±0.03(stat.)±0.03(syst.),B(Ξc0→Σ+K∗−)/B(Ξc0→Ξ−π+)=0.34±0.06(stat.)±0.02(syst.), where the uncertainties are statistical and systematic, respectively. We obtainB(Ξc0→ΛK¯∗0)=(3.3±0.3(stat.)±0.2(syst.)±1.0(ref.))×10−3,B(Ξc0→Σ0K¯∗0)=(12.4±0.5(stat.)±0.5(syst.)±3.6(ref.))×10−3,B(Ξc0→Σ+K∗0)=(6.1±1.0(stat.)±0.4(syst.)±1.8(ref.))×10−3, where the uncertainties are statistical, systematic, and from B(Ξc0→Ξ−π+), respectively. The asymmetry parameters α(Ξc0→ΛK¯∗0) and α(Ξc0→Σ+K∗−) are 0.15 ± 0.22(stat.) ± 0.04(syst.) and −0.52 ± 0.30(stat.) ± 0.02(syst.), respectively, where the uncertainties are statistical followed by systematic. [Figure not available: see fulltext.]

We report a measurement of the CP-violation parameter φ1 obtained in a time-dependent analysis of B0→D(∗)0h0 decays followed by D0→KS0π+π- decay. A model-independent measurement is performed using the binned Dalitz plot technique. The measured value is φ1=11.7°±7.8°(stat)±2.1°(syst). Treating sin2φ1 and cos2φ1 as independent parameters, we obtain sin2φ1=0.43±0.27(stat)±0.08(syst) and cos2φ1=1.06±0.33(stat)-0.15+0.21(syst). The results are obtained with a full data sample of 772×106BB pairs collected near the (4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.