Search

International audience; The Belle II experiment at the SuperKEKB energy-asymmetric e+e− collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The design luminosity of the machine is 6⋅1035cm−2s−1 and the Belle II experiment aims to ultimately record 50ab−1 of data, a factor of 50 more than its predecessor. With this data set, Belle II will be able to measure the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements with unprecedented precision and explore flavor physics with B and D mesons, and τ leptons. Belle II has also a unique capability to search for low-mass dark matter and low-mass mediators. In this work, I will review the latest results from Belle II.

We report the recent measurements performed using the data sample collected from 2019 to 2022 by the Belle~II experiment~\cite{Belle2:TDR} at $\Upsilon(4S)$ resonance, corresponding to an integrated luminosity of $362~\mathrm{fb}^{-1}$. We present the measurement of $B$ lifetime and mixing frequency, the time dependent CP-violation analyses using the $B^0\to J\psi K_S^0$, $B^0\to \phi K_S^0$, $B^0\to K_S^0K_S^0K_S^0$, $B^0\to K_S^0\pi^0$ decays and the implication of the latter for the isospin sum rule, the observation of $B\to D^{(*)} K^-K_S^0$ decays, the analysis of $B\to X_s\gamma$. We also present the measurements of the angle $\gamma$ using $B\to DK$ decays, with the combined dataset collected by Belle and Belle II., Comment: Contribution to the 2023 QCD session of the 57th Rencontres de Moriond

We study the discovery potential of massive graviton-like spin-2 particles coupled to standard model fields, produced in photon-photon collisions at the Large Hadron Collider (LHC) as well as in electron-positron ($e^+e^-$) collisions, within an effective theory with and without universal couplings. Our focus is on a massive graviton G coupled to the electromagnetic field, which decays via $\mathrm{G}\to \gamma \gamma$ and leads to a resonant excess of diphotons over the light-by-light scattering continuum at the LHC, and of triphoton final states at $e^+e^-$ colliders. Based on similar searches performed for pseudoscalar axion-like particles (ALPs), and taking into account the different cross sections, $\gamma \gamma$ partial widths, and decay kinematics of the pseudoscalar and tensor particles, we reinterpret existing experimental bounds on the ALP-$\gamma$ coupling into G-$\gamma$ ones. Using the available data, exclusion limits on the graviton-photon coupling are set down to $g_{\mathrm{G}\gamma\gamma}\approx 1$--0.05~TeV$^{-1}$ for masses $m_\mathrm{G} \approx 100$~MeV--2~TeV. Such bounds can be improved by factors of 100 at Belle~II in the low-mass region, and of 4 at the HL-LHC at high masses, with their expected full integrated luminosities., Comment: 26 pages, 7 figures

Additional spin-0 particles appear in many extensions of the standard model. We search for long-lived spin-0 particles $S$ in $B$-meson decays mediated by a $b\to s$ quark transition in $e^+e^-$ collisions at the $\Upsilon(4S)$ resonance at the Belle II experiment. Based on a sample corresponding to an integrated luminosity of $189 \mathrm{\,fb}^{-1}$, we observe no evidence for signal. We set model-independent upper limits on the product of branching fractions $\mathrm{Br}(B^0\to K^*(892)^0(\to K^+\pi^-)S)\times \mathrm{Br}(S\to x^+x^-)$ and $\mathrm{Br}(B^+\to K^+S)\times \mathrm{Br}(S\to x^+x^-)$, where $x^+x^-$ indicates $e^+e^-, \mu^+\mu^-, \pi^+\pi^-$, or $K^+K^-$, as functions of $S$ mass and lifetime at the level of $10^{-7}$.

41st International Conference on High Energy physics, ICHEP2022, Bologna, Italy, 6 Jul 2022 - 13 Jul 2022; Proceedings of Science / International School for Advanced Studies (ICHEP2022), 743 (2022). doi:10.22323/1.414.0743, We report on the recent measurements of electroweak and radiative penguin $B$ decays at the Belle II experiment. We use samples of electron-positron collisions collected at the $\Upsilon(4S)$ resonance. We present the measurement of the branching fractions of $B^{+/0}\to K^*(892)^{+/0}\ell^+\ell^-~(\ell=e, \mu)$, $B^{+/0}\to K^{+/0}J/\psi$, and $B^{+/0}\to X_s\gamma$ decays in the data corresponding to 189 fb$^{-1}$ of integrated luminosity. We also present a search of $B^+\to K^+\nu\bar\nu$ decay in the data corresponding to 63 fb$^{-1}$ of integrated luminosity., Published by SISSA, Trieste

My technical project and STS research work evolves around engineering applications designed to benefit fellow human beings and I am proud to provide more details on the. The aim of the project was to evaluate gait, plantar pressure, and foot function with insole sensors that are reliable and durable enough to accurately capture data wherever activity takes place and without compromising natural motion. On the other hand, my STS project focused on a big picture analysis of low Earth orbit (LEO) satellites that are going to change our course of wireless communications forever. Although my technical and STS projects are only loosely related because the topics were pursued on different occasions, working on each of the projects allowed me to cover a breadth of topics that greatly contributed to my learning as an engineer. My technical project was created over a long semester of hard work with my peers each: Eric, Kieran, Merron and Xinyuan, a team of dedicated engineers who I appreciate working with. The project was a smart shoe-insole with seven pressure sensors strategically placed throughout areas of the sole that experience the most pressure during physical activity. The data collected from these sensors then get transmitted using Bluetooth to an external software application, which will visually display the data in real time. The goal of this project was to enable this smart insole to be used as a medical tool for use in physical therapy and diagnostics, as well as a tool to be used by athletes to evaluate and improve their performance. Foot pressure distribution (FPD) is a useful metric for the diagnosis of potential issues in a person’s foot or gait. FPD can be used to identify foot deformities, diagnose gait disorders, and provide strategies for preventing foot ulcers in diabetes. Outside of medical usage, the technology can be used by athletes and coaches; for example, golf players can use this data to assess the stability and the form of their swings. This project was chosen because each member in the capstone team has either actively played a sport in the past or currently are engaged in sports. We wanted to provide a tool to benefit those who play sports. Upon doing further research about the benefits of knowing FPD, the scope of the project expanded to be both a sports improvement tool and a medical diagnostic tool. As mentioned before, my STS project provides an analysis of low Earth orbit satellite internet by giant Silicon Valley companies using the framework of Actor Network Theory. Internet, a global network of devices that connect humans and non-humans, is a basic need in the 21st century, however, an estimated 4 billion people still do not have access to it. As part of the solution, a significant expansion of the satellite Internet sector is taking place, bringing with it big hopes for social and economic growth. Satellite Internet has resurfaced in recent years as a viable alternative to laying thousands of miles of fiber optic cable, a practice that is time and energy-intensive and associated with high operating costs. In order to compete with broadband service, new Silicon Valley-associated companies such as SpaceX, OneWeb and Amazon are developing innovative constellations of small satellites in non-synchronous orbits. The constellations reduce production costs and improves signal delay, allowing them to provide cheap, high-speed Internet access around the globe. The Actor-Network Theory (ANT) methodology is applied in this study to explain the increasing popularity of commercial satellites, as ANT highlights how linkages and their dynamic result in the emergence of new entities, for example the new emerging organizations and the uncertainties they face, which is core part of this paper. In this paper, ANT is applied to explore what are the factors that contribute to renewed interest in satellite connectivity and what are the non-human actors that pose challenges to the industry.

Journal of high energy physics 04(4), 110 (2022). doi:10.1007/JHEP04(2022)110, We report a measurement of the electric dipole moment of the $τ$ lepton $(d_{τ})$ using an 833 fb$^{−1}$ data sample collected near the $Υ(4S)$ resonance, with the Belle detector at the KEKB asymmetric-energy e$^{+}$e$^{−}$ collider. Using an optimal observable method, we obtain the real and imaginary parts of $d_{τ}$ as Re(d$_{τ}$) = (−0.62 ± 0.63) × 10$^{−17}$ecm and Im($d_{τ}$) = (−0.40 ± 0.32) × 10$^{−17}$ecm, respectively. These results are consistent with null electric dipole moment at the present level of experimental sensitivity and improve the sensitivity by about a factor of three.[graphic not available: see fulltext], Published by SISSA, [Trieste]

Physical review / D 107(7), 072002 (2023). doi:10.1103/PhysRevD.107.072002, We present measurements of the first to fourth moments of the lepton mass squared $q^2$ of \mbox{$B \to X_c \, \ell\, \bar \nu_{\ell}$} decays for $\ell = e, \mu$ and with $X_c$ a hadronic system containing a charm quark. These results use a sample of electron-positron collisions at the $\Upsilon(4S)$ resonance corresponding to $62.8 \, \mathrm{fb}^{-1}$ of integrated luminosity and collected by the Belle II experiment in 2019 and 2020. To identify the $X_c$ system and reconstruct $q^2$, one of the $B$ mesons from an $\Upsilon(4S) \to B \kern 0.18em\overline{\kern -0.18em B}$ decay is fully reconstructed in a hadronic decay mode using a multivariate $B$ tagging algorithm. We report raw and central moments for $ q^2 > 1.5 \; \mathrm{GeV^2/c^4}$ up to $q^2 > 8.5 \; \mathrm{GeV^2/c^4}$, probing up to 77% of the accessible \mbox{$B \to X_c \, \ell\, \bar \nu_{\ell}$} phase space. This is the first measurement of moments in the experimentally challenging range of $[ 1.5, 2.5 ] \, \mathrm{GeV^2/c^4}$., Published by Inst., Woodbury, NY

We present a study of a singly Cabibbo-suppressed decay $\Lambda_c^+\to{}pK_S^0K_S^0$ and a Cabibbo-favored decay $\Lambda_c^+\to{}pK_S^0\eta$ based on 980 $\rm fb^{-1}$ of data collected by the Belle detector, operating at the KEKB energy-asymmetric $e^+e^-$ collider. We measure their branching fractions relative to $\Lambda_c^+\to{}pK_S^0$: $\mathcal{B}(\Lambda_c^+\to{}pK_S^0K_S^0)/\mathcal{B}(\Lambda_c^+\to{}pK_S^0)={(1.48 \pm 0.08 \pm 0.04)\times 10^{-2}}$ and $\mathcal{B}(\Lambda_c^+\to{}pK_S^0\eta)/\mathcal{B}(\Lambda_c^+\to{}pK_S^0)={(2.73\pm 0.06\pm 0.13)\times 10^{-1}}$. Combining with the world average $\mathcal{B}(\Lambda_c^+\to{}pK_S^0)$, we have the absolute branching fractions: $\mathcal{B}(\Lambda_c^+\to{}pK_S^0K_S^0) = {(2.35\pm 0.12\pm 0.07 \pm 0.12 )\times 10^{-4}}$ and $\mathcal{B}(\Lambda_c^+\to{}pK_S^0\eta) = {(4.35\pm 0.10\pm 0.20 \pm 0.22 )\times 10^{-3}}$. The first and second uncertainties are statistical and systematic, respectively, while the third ones arise from the uncertainty on $\mathcal{B}(\Lambda_c^+\to{}pK_S^0)$. The mode $\Lambda_c^+\to{}pK_S^0K_S^0$ is observed for the first time and has a statistical significance of $>\!10\sigma$. The branching fraction of $\Lambda_c^+\to{}pK_S^0\eta$ has been measured with a threefold improvement in precision over previous results and is found to be consistent with the world average., Comment: 8 pages, 4 figures, accepted by Phys. Rev. D

The Silicon Vertex Detector of Belle II is a state-of-the-art tracking and vertexing system based on double-sided silicon strip sensors, designed and fabricated by a large international collaboration in the period 2012--2018. Since 2019 it has been in operation providing high quality data with a small number of defective channels (99%), a good signal-to-noise ratio (well in excess of 10 for all sensor configurations and tracks). Together with the good control over the alignment, these are all essential factors to achieve good tracking reconstruction and physics performance. In this extended paper we try to document all the aspects of the SVD challenges and achievements, in the spirit of providing information to the broader community and help the development of high quality detector systems, which are fundamental tools to carry out physics research., 199 pages, 152 figures

This article surveys the important questions attached to unitarity tests of the Cabibbo-Kobayashi-Maskawa matrix, with a focus on the direct determinations of the magnitude of CKM matrix elements. The current CKM anomalies are discussed and the clear-cut prospects at LHCb and Belle II envisaged. The anticipated precision on $C\!P$-conserving and $C\!P$-violating observables at the projected upgrades of the LHCb and Belle~II experiments is examined from the point of view of the search for New Physics in $B$-meson mixing, addressing the bottlenecks in precision for the interpretation of the measurements for future experiments and highlighting the related theoretical and experimental challenges. The vibrant prospects at future $e^+e^-$ colliders running at the $Z^0$ pole and $W^+W^-$ are eventually discussed., Comment: 18 pages, 5 figures, submitted to the Proceedings of the US Community Study on the Future of Particle Physics (Snowmass 2021)

20th International Workshop on Advanced Computing and Analysis Techniques in Physics Research, ACAT 2021, Daejeon, Korea, Republic of, 29 Nov 2021 - 3 Dec 2021; Journal of physics / Conference Series 2438(1), 012052 (2023). doi:10.1088/1742-6596/2438/1/012052, The physics output of modern experimental HEP collaborations hinges not only on the quality of its software but also on the ability of the collaborators to make the best possible use of it. With the COVID-19 pandemic making in-person training impossible, the training paradigm at Belle II was shifted from periodic workshops towards guided self-study.To that end, the study material was rebuilt from scratch as a series of modular and hands-on lessons tightly integrated with the software documentation using Sphinx. Each lesson contains multiple exercises that are supplemented with hints and complete solutions. Rather than duplicating information, students are systematically taught to work with the technical reference documentation to find the important sections for themselves. Unit tests ensure that all examples work with different software versions, and feedback buttons make it easy to submit comments for improvements., Published by IOP Publ., Bristol

Decays of neutral D mesons to final states containing K + π's could provide evidence for CP-violation from a source not accounted for in the Standard Model. Due to the interference between Cabibbo-favored and Cabibbo-suppressed transitions, a decay rate asymmetry of D0 → K0S π0 compared to D0 → K0Lπ0 has been predicted to be non-zero. If New Physics interferes in doubly Cabibbo-suppressed D decays, the measurement of this asymmetry would differ from the predicted value and may provide evidence for CP-violation beyond the CKM mechanism. I present an analysis method to measure this branching fraction asymmetry, R(D0) ≡ B(D0→K0S π0)−B(D0→K0L π0)/(B(D0→K0Sπ0)+B(D0→K0Lπ0)), utilizing e+e− → cc events in the Belle dataset. Doctor of Philosophy The Universe appears to be made almost entirely of matter rather than antimatter; however, matter and antimatter should have been created in equal amounts in the Big Bang. We do not know exactly why we observe so much more matter as compared to antimatter. The Standard Model (SM) of particle physics accounts for some of the asymmetry through Charge-Parity (CP) symmetry violation, which explains how particles behave differently than their corresponding antiparticles. In the current state of the SM, some CP-violation is allowed in decays via the weak force, but the theory does not account for enough CP violation to explain the amount of matter-antimatter asymmetry observed in the Universe. Decays of a D meson to a kaon (K meson) plus one or more pions (π mesons) via a new mechanism beyond the weak force could provide evidence of a new source of CP-violation. In this analysis, I present a method for analyzing the decays of neutral D mesons to a neutral kaon and a neutral pion in the Belle dataset to test the SM.

International audience; The Belle II silicon vertex detector is one of the vertex detectors in the Belle II experiment. The detector reads out the signals from the double-sided silicon strip sensors with the APV25 front-end readout ASIC, adopting the chip-on-sensor concept to minimize the strip noise. The detector has been operated in the experiment since the spring of 2019. Analyzing the acquired data during the beam collisions, the excellent performance of the detector is confirmed. Also, the radiation dose and 1-MeV equivalent neutron fluence of the detector are estimated using the measured dose rates of the diamond sensors installed on the beam pipe and are compared with the measured radiation effects in the strip noise, leakage current, and depletion voltage. This paper briefly introduces the main features of the silicon vertex detector, and then reports on the measured performance and radiation effects of the first two years of running experience of the detector.

The DESY II Test Beam Facility is a key infrastructure for modern high energy physics detector development, providing particles with a small momentum spread in a range from 1 to 6 GeV to user groups e.g. from the LHC experiments and Belle II as well as generic detector R&D. Beam telescopes are provided in all three test beam areas as precise tracking reference without time stamping, with triggered readout and a readout time of > 115 μs. If the highest available rates are used, multiple particles are traversing the telescopes within one readout frame, thus creating ambiguities that cannot be resolved without additional timing layers. Several upgrades are currently investigated and tested: Firstly, a fast monolithic pixel sensor, the TelePix, to provide precise track timing and triggering on a region of interest is proposed to overcome this limitation. The TelePix is a 180 nm HV-CMOS sensor that has been developed jointly by DESY, KIT and the University of Heidelberg and designed at KIT. In this publication, the performance evaluation is presented: The difference between two amplifier designs is evaluated. A high hit detection efficiency of above 99.9% combined with a time resolution of below 4 ns at negligible pixel noise rates is determined. Finally, the digital hit output to provide region of interest triggering is evaluated and shows a short absolute delay with respect to a traditional trigger scintillator as well as an excellent time resolution. Secondly, a fast LGAD plane has been proposed to provide a time resolution of a few 10 ps, which is foreseen to drastically improve the timing performance of the telescope. Time resolutions of below 70 ps have been determined in collaboration with the University of California, Santa Barbara.

International audience; We report the results of the first search for the decay Bs0→η′η using 121.4 fb-1 of data collected at the ϒ(5S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We observe no significant signal and set a 90% confidence-level upper limit of 6.5×10-5 on the branching fraction of this decay.

International audience; Belle II is the next generation B Factory experiment operating at the SuperKEKB accelerator complex at KEK in Tsukuba, Japan. It is expected to collect 50 ab−1 of data, with a target instantaneous luminosity of 6.5 × 1035 cm−2s−1, which is about 30 times larger than its predecessor, Belle. In view of the ever increasing Belle II data sample, accurate simulation of the detector is growing in importance. This poses a challenging task of compromising between the realistic modeling of the response of individual detector components and reasonable performance in terms of CPU time of the simulation. In this paper we describe the simulation of the silicon vertex detector, its performance against collision data and optimization.

International audience; I review the current status of the $B$ anomalies in $b\to c\ell\bar\nu_\ell$ and $b\to s\ell\ell$ transitions. After recalling the experimental situation in each case, I discuss the elements of the Standard Model (SM) predictions and the patterns of New Physics arising in model-independent analyses, before discussing some of the models beyond the SM proposed to explain these patterns.

Physical review / D 104(9), 094007 (2021). doi:10.1103/PhysRevD.104.094007, Using the approach based on conformal symmetry we calculate the two-loop coefficient function for the axial-vector contributions to two-photon processes in the $\overline{\rm MS}$ scheme. This is the last missing element for the complete next-to-next-to-leading order (NNLO) calculation of the the pion transition form factor $\gamma^\ast\gamma\to \pi $ in perturbative QCD. The corresponding high-statistics measurement is planned by the Belle II collaboration and will allow one to put strong constraints on the pion light-cone distribution amplitude. The calculated NNLO corrections prove to be rather large and have to be taken into account. The same coefficient function determines the contribution of the axial-vector generalized parton distributions to deeply-virtual Compton scattering which is investigated at the JLAB 12 GeV accelerator, by COMPASS at CERN, and in the future will be studied at the Electron Ion Collider EIC., Published by Inst., Melville, NY

Physical review / D 104(5), 056019 (2021). doi:10.1103/PhysRevD.104.056019, We present the first open-source analysis of fragmentation functions (FFs) of charged pions (entitled ipm-xfitter) performed at next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) accuracy in perturbative QCD using the xfitter framework. This study incorporates a comprehensive and up-to-date set of pion production data from single-inclusive annihilation (SIA) processes, together with the most recent measurements of inclusive cross-sections of single pion by the BELLE collaboration. The determination of pion FFs along with their theoretical uncertainties is performed in the zero-mass variable-flavor number scheme (ZM-VFNS). We also present comparisons of our FFs set with recent fits from the literature. The resulting NLO and NNLO pion FFs provide valuable insights for applications in present and future high-energy analysis of pion final state processes., Published by Inst., Melville, NY

International audience; After its commissioning in 2018, the Belle II experiment has started registering first physics data delivered by SuperKEKB in 2019. The Belle II physics program focuses on the search for physics beyond the standard model with precise measurements in the flavour sector. The huge targeted dataset and the B-factory particular collision scheme will help to significantly improve the experimental precision on the three angles of the bd CKM unitarity triangle. These measurements are based on time-dependent CP asymmetry analyses for the angles phi1 and phi2, and on the reconstruction of many B and D hadronic decay modes for phi3. In this proceeding article are reported the first look at these ingredients reconstructed with early Belle II data, and the expected Belle II sensitivity on phi1, phi2 and phi3 with more data.

International audience; In the forward end-cap of the Belle II spectrometer, an innovative proximity focusing Ring Imaging Cherenkov counter with a multilayer focusing aerogel radiator has been installed. The detector is designed to be operated in a magentic field of 1.5 T, and consists of a double layer aerogel radiator, an expansion volume and a photon detector. In total 420 Hamamatsu hybrid avalanche photo sensors with 144 channels each are used to read out single Cherenkov photons with high efficiency. We expect the device to provide better than 4s separation of pions from kaons in the full kinmatic region of the experiment, from 0.5 GeV/c to 4 GeV/c. The detector components have been successfully produced and installed in the spectrometer. After the commissioning phase in 2018, the detector is now included in the Belle II data taking, and is expected to contribute substantially to the performance of the spectrometer in looking for rare decays of B and D mesons, and of tau leptons. In this contribution we review the detector design and present results of the first detector performance studies.

Following the updated measurement of the lepton flavour universality (LFU) ratio R_K in B -> Kll decays by LHCb, as well as a number of further measurements, e.g. R_K* by Belle and B_s -> mu mu by ATLAS, we analyse the global status of new physics in b -> s transitions in the weak effective theory at the b-quark scale, in the Standard Model effective theory at the electroweak scale, and in simplified models of new physics. We find that the data continues to strongly prefer a solution with new physics in semi-leptonic Wilson coefficients. A purely muonic contribution to the combination C_9 = -C_10, well suited to UV-complete interpretations, is now favoured with respect to a muonic contribution to C_9 only. An even better fit is obtained by allowing an additional LFU shift in C_9. Such a shift can be renormalization-group induced from four-fermion operators above the electroweak scale, in particular from semi-tauonic operators, able to account for the potential discrepancies in b -> c transitions. This scenario is naturally realized in the simplified U_1 leptoquark model. We also analyse simplified models where a LFU effect in b -> sll is induced radiatively from four-quark operators and show that such a setup is on the brink of exclusion by LHC di-jet resonance searches., 41 pages, 20 figures, 3 tables. Originally presented at Moriond EW 2019 on March 22, 2019. v2: Numerics updated including the Belle RD(*) update, clarifications and references added

We report the first observation of the radiative decay of the ϒ(1S) into a charmonium state. The significance of the observed signal of ϒ(1S)→γχ_{c1} is 6.3 standard deviations including systematics. The branching fraction is calculated to be B[ϒ(1S)→γχ_{c1}]=[4.7_{-1.8}^{+2.4}(stat)_{-0.5}^{+0.4}(sys)×10^{-5}]. We also searched for ϒ(1S) radiative decays into χ_{c0,2} and η_{c}(1S,2S), and set upper limits on their branching fractions. These results are obtained from a 24.9 fb^{-1} data sample collected with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider at a center-of-mass energy equal to the ϒ(2S) mass using ϒ(1S) tagging by the ϒ(2S)→ϒ(1S)π^{+}π^{-} transitions.

Journal of high energy physics 2020(5), 34 (2020). doi:10.1007/JHEP05(2020)034, The first dedicated search for the η$_{c2}$(1D) is carried out using the decays B$^{+}$→ η$_{c2}$(1D)K$^{+}$, B$^{0}$ → η$_{c2}$(1D)$ {K}_S^0 $, B$^{0}$→ η$_{c2}$(1D)π$^{−}$K$^{+}$, and B$^{+}$→ η$_{c2}$(1D)π$^{+} {K}_S^0 $ with η$_{c2}$(1D) → h$_{c}$γ. No significant signal is found. For the η$_{c2}$(1D) mass range between 3795 and 3845 MeV/c$^{2}$, the branching-fraction upper limits are determined to be ℬ(B$^{+}$→ η$_{c2}$(1D)K$^{+}$) × ℬ(η$_{c2}$(1D) → h$_{c}$γ) < 3.7 × 10$^{−5}$, ℬ(B$^{0}$→ η$_{c2}$(1D)K$^{0}$) × ℬ(η$_{c2}$(1D) → h$_{c}$γ) < 3.5 × 10$^{−5}$, ℬ(B$^{0}$→ η$_{c2}$(1D)π$^{−}$K$^{+}$) × ℬ(η$_{c2}$(1D) → h$_{c}$γ) < 1.0 × 10$^{−4}$, and ℬ(B$^{+}$→ η$_{c2}$(1D)π$^{+} {K}_S^0 $) × ℬ(η$_{c2}$(1D) → h$_{c}$γ) < 1.1 × 10$^{−4}$ at 90% C.L. The analysis is based on the 711 fb$^{−1}$ data sample collected on the ϒ(4S) resonance by the Belle detector, which operated at the KEKB asymmetric-energy e$^{+}$e$^{−}$ collider.[graphic not available: see fulltext], Published by SISSA, [Trieste]

We report the measurement of $e^+e^- \to D^+_sD^*_{s2}(2573)^-+c.c.$ via initial-state radiation using a data sample of an integrated luminosity of 921.9 fb$^{-1}$ collected with the Belle detector at the $\Upsilon(4S)$ and nearby. We find evidence for an enhancement with a 3.4$\sigma$ significance in the invariant mass of $D^+_sD^*_{s2}(2573)^- +c.c.$ The measured mass and width are $(4619.8^{+8.9}_{-8.0}({\rm stat.})\pm2.3({\rm syst.}))~{\rm MeV}/c^{2}$ and $(47.0^{+31.3}_{-14.8}({\rm stat.})\pm4.6({\rm syst.}))~{\rm MeV}$, respectively. The mass, width, and quantum numbers of this enhancement are consistent with the charmonium-like state at 4626 MeV/$c^2$ recently reported by Belle in $e^+e^-\to D^+_sD_{s1}(2536)^-+c.c.$ The product of the $e^+e^-\to D^+_sD^*_{s2}(2573)^-+c.c.$ cross section and the branching fraction of $D^*_{s2}(2573)^-\to{\bar D}^0K^-$ is measured from $D^+_sD^*_{s2}(2573)^-$ threshold to 5.6 GeV., Comment: 9 pages, 4 figures

Physical review / D 103(3), 032003 (1-8) (2021). doi:10.1103/PhysRevD.103.032003, We measure the time-dependent CP violation parameters in B$^0$→K$^0_S$K$^0_S$K$^0_S$ decays using 772×10$^6B{\overline{B}}$ pairs collected at the $Υ$(4S) resonance with the Belle detector at the KEKB asymmetric-energy e$^+$e$^−$ collider. The obtained mixing-induced and direct CP asymmetries are −0.71±0.23 (stat)±0.05 (syst) and 0.12±0.16 (stat)±0.05 (syst), respectively. These values are consistent with the Standard Model predictions. The significance of CP violation differs from zero by 2.5 standard deviations., Published by Inst.302363, Melville, NY

We report new measurements of the production cross sections of pairs of charged pions and kaons as a function of their fractional energies using various fractional-energy definitions. Two different fractional-energy definitions were used and compared to the conventional fractional-energy definition reported previously. The new variables aim at either identifying dihadron cross sections in terms of single-hadron fragmentation functions, or to provide a means of characterizing the transverse momentum created in the fragmentation process. The results were obtained applying the updated initial-state radiation correction used in other recent Belle publications on light-hadron production cross sections. In addition, production cross sections of single charged pions, kaons, and protons were also updated using this initial-state radiation correction. The cross sections are obtained from a $558\,{\rm fb}^{-1}$ data sample collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider., Comment: 12 pages, 9 figures, submitted to PRD

We report the measurement of e(+) e(-) -> D-s(+) Ds(2)*(2573)(-) c.c. via initial-state radiation using a data sample of an integrated luminosity of 921.9 fb(-1) collected with the Belle detector at the Upsilon(4S) and nearby. We find evidence for an enhancement with a 3.4 sigma significance in the invariant mass of Ds+Ds2*(2573)(-) + c.c. The measured mass and width are (4619.8(-8.0)(+8.9)(stat.) +/- 2.3(syst.)) MeV/c(2) and (47.0(-14.8)(+31.3)(stat.) +/- 4.6(syst.)) MeV, respectively. The mass, width, and quantum numbers of this enhancement are consistent with the charmoniumlike state at 4626 MeV/c(2) recently reported by Belle in e(+) e(-) -> Ds+ Ds1(2536)(-) c.c. The product of the e(+) e(-) -> D-s(+) Ds(2)*(2573)(-) + c.c. cross section and the branching fraction of D-s2*(2573)(-) -> (D) over bar K-0(-) is measured from Ds+Ds2*(2573)(-) threshold to 5.6 GeV. We thank the KEKB group for the excellent operation of the accelerator; the KEK cryogenics group for the efficient operation of the solenoid; and the KEK computer group, and the Pacific Northwest National Laboratory (PNNL) Environmental Molecular Sciences Laboratory computing group for strong computing support; and the National Institute of Informatics, and Science Information NETwork 5 for valuable network support. We acknowledge support from the Ministry of Education, Culture, Sports, Science, and Technology of Japan, the Japan Society for the Promotion of Science, and the Tau-Lepton Physics Research Center of Nagoya University; the Australian Research Council including Grants No. DP180102629, No. DP170102389, No. DP170102204, No. DP150103061, and No. FT130100303; Austrian Science Fund under Grant No. P 26794-N20; the National Natural Science Foundation of China under Contracts No. 11435013, No. 11475187, No. 11521505, No. 11575017, No. 11675166, and No. 11705209; Key Research Program of Frontier Sciences, Chinese Academy of Sciences (CAS), Grant No. QYZDJ-SSW-SLH011; the CAS Center for Excellence in Particle Physics; the Shanghai Pujiang Program under Grant No. 18PJ1401000; the Ministry of Education, Youth and Sports of the Czech Republic under Contract No. LTT17020; the Carl Zeiss Foundation, the Deutsche Forschungsgemeinschaft, the Excellence Cluster Universe, and the VolkswagenStiftung; the Department of Science and Technology of India; the Istituto Nazionale di Fisica Nucleare of Italy; National Research Foundation of Korea Grants No. 2015H1A2A1033649, No. 2016R1D1A1B01010135, No. 2016K1A3A7A09005 603, No. 2016R1D1A1 B02012900, No. 2018R1A2B3003 643, No. 2018R1A6A1 A06024970, and No. 2018R1D1 A1B07047294; Radiation Science Research Institute, Foreign Large-Size Research Facility Application Supporting project, the Global Science Experimental Data Hub Center of the Korea Institute of Science and Technology Information and KREONET/GLORIAD; the Polish Ministry of Science and Higher Education and the National Science Center; the Grant of the Russian Federation Government, Agreement No. 14.W03.31.0026; the Slovenian Research Agency; Ikerbasque, Basque Foundation for Science, Spain; EU Horizon 2020 research and innovation programme, STRONG-2020 project, under Grant No. 824093; the Swiss National Science Foundation; the Ministry of Education and the Ministry of Science and Technology of Taiwan; and the U.S. Department of Energy and the National Science Foundation.

We study the Standard Model and the new physics predictions for the lepton-flavour-universality violating (LFUV) ratios in various $b\to s \ell^+\ell^-$ channels with scalar, pseudoscalar, vector, axial-vector, and $\Lambda$ baryon final states, considering both unpolarized and polarized final state hadrons. In order to formulate physical observables, we use the model independent effective Hamiltonian approach and employ the helicity formalism. We provide the explicit expressions of the helicity amplitudes in terms of the Wilson coefficients and the hadronic form factors by using the same kinematical configuration and polarization conventions for all the decay channels.We perform the numerical analysis with new physics scenarios selected from the recent global fits to $b\to s\ell^+\ell^-$ data, having specific new physics model interpretations. We find that some of the LFUV ratios for these complementary channels in different kinematical regions have high sensitivity to new physics and the future measurements of them in Belle II and LHCb experiments, along with testing new physics/LFUV, can help to distinguish among some of the different new physics possibilities., Comment: 42 pages, 6 figures, 13 tables; version accepted for publication in NPB

Like the two-photon and two-gluon decays of the P-wave charmonium state for which the Born term produces a very simple decays amplitude, the Born term for the processes c d ‾ → ( π , K ) l ν and b d ‾ → ( π , K ) l ν , could also produce a simple expression for D and B meson semileptonic decays with a light meson π, K in the final state. The pole term at q 2 = m B 2 + m π 2 for B → π and at q 2 = m D 2 + m K 2 for D → K form factor, are generated by the Born term and given as: f + ( 0 ) / ( 1 − q 2 / ( m H 2 + m π 2 ) ) , with H = D, B for D, B → π form factors, and f + ( 0 ) / ( 1 − q 2 / ( m H 2 + m K 2 ) ) for B, D → K form factor. These pole dominance terms describe rather well the q2-behavior of the form factors observed in the BaBar, Belle and BESIII measurements and in lattice simulation. In particular, the D → K form factors are in good agreement with the measured values in the whole range of q2 showing evidence for S U(3) breaking with the presence of the m K 2 term in the quark propagator, but some corrections to the Born term are needed at large q2 for D, B → π form factors.

Physics letters / B 822, 136701 (2021). doi:10.1016/j.physletb.2021.136701, New particles $��$ in the MeV-GeV range produced at colliders and escaping detection can be searched for at operating b- and $��$-factories such as Belle II. A typical search topology involves pair-produced $��s$ (or mesons), one of which decaying to visibles plus the $��$, and the other providing a tag. One crucial impediment of these searches is the limited ability to reconstruct the parents' separate boosts. This is the case in the ���typical��� topology where both decay branches include escaping particles. We observe that such topology lends itself to the use of kinematic variables such as M$_2$, designed for pairwise decays to visibles plus escaping particles, and endowed with a built-in (���MAOS���) way to efficiently guess the parents' separate boosts. Starting from this observation, we construct several kinematic quantities able to discriminate signal from background, and apply them to a benchmark search, $�� ��� e + ��$, where $��$ can be either an axion-like particle or a hidden photon. Our considered variables can be applied to a wider range of topologies than the current reference technique, based on the event thrust, with which they are nearly uncorrelated. Application of our strategy leads to an improvement by a factor close to 3 in the branching-ratio upper limit for $�� ��� e ��$, with respect to the currently expected limit, assuming $m_�� ���$1 MeV. For example, we anticipate a sensitivity of 1.7��10$^{���5}$ with the data collected before the 2022 shutdown., Published by North-Holland Publ., Amsterdam

Bu çalışma, 01-03 Haziran 2016 tarihleri arasında İstanbul[Türkiye]’da düzenlenen 6. Congress and Exhibition on International Advances in Applied Physics and Materials Science (APMAS)’da bildiri olarak sunulmuştur. In addition to PWO and CsI(Tl) crystals, cerium doped LYSO crystal is considered for the electromagnetic calorimeter part of the Turkish Accelerator Center Particle Factory (TAC-PF) detector, because of its high light yield, fast decay time and good radiation hardness. In this work, LYSO crystals arranged in 3 x 3 and 5 x 5 matrices have been simulated against photons in the energy range between 50 MeV and 2 GeV, using Geant4 simulation code. Energy resolutions have been estimated considering the contribution of photoelectron statistics coming from the avalanche and PIN photodiodes.

We present a brief update of our model-independent analyses of the b->s data presented in the articles published in Phys. Rev. D96 (2017) 095034 and Phys. Rev. D98 (2018) 095027 based on new data on R_K by LHCb, on R_{K^*} by Belle, and on B_{s,d}-> mu^+ mu^- by ATLAS., Comment: 7 pages, 3 figures, 3 tables. Addendum to Phys. Rev. D96 (2017) 095034 and Phys. Rev. D98 (2018) 095027

Memory disorders without a direct neural substrate still belong to the riddles in neuroscience. Although they were for a while dissociated from research and clinical arenas, risking becoming forgotten diseases, they sparked novel interests, paralleling the refinements in functional neuroimaging and neuropsychology. Although Endel Tulving has not fully embarked himself on exploring this field, he had published at least one article on functional amnesia (Schacter et al., 1982) and ignited a seminal article on amnesia with mixed etiology (Craver et al., 2014). Most importantly, the research of Endel Tulving has provided the researchers and clinicians in the field of dissociative or functional amnesia with the best framework for superiorly understanding these disorders through the lens of his evolving concept of episodic memory and five long term memory systems classification, which he developed and advanced. Herein we use the classification of long-term memory systems of Endel Tulving as well as his concepts and views on autonoetic consciousness, relationships between memory systems and relationship between episodic memory and emotion to describe six cases of dissociative amnesia that put a challenge for researchers and clinicians due to their atypicality. We then discuss their possible triggering and maintaining mechanisms, pointing to their clinical heterogeneity and multifaceted causally explanatory frameworks.

This thesis presents a feasibility study of a method for KL calibration at the Belle II experiment, using initial state radiation (ISR) production of the KS KL final state. By reconstructing the ISR photon, and the KS and subtracting their energy-momentum 4-vectors from that of the known e+ e − initial state, the 4-vector of the KL may be determined. Due to the loss of second order ISR photons and lost photon energy from incomplete electromagnetic shower reconstruction, a correction is applied to the photon energy. The expected efficiency, after all of the appropriate selections to isolate signal events were applied, was found to be of order 1%. This corresponds to roughly 100 well-reconstructed events per f b −1 of integrated luminosity produced at Belle II, with the difference between the MC generated and reconstructed KL energy found to be of the order of 5 MeV and with the angle between the truth and determined K L vector found to be of the order 0.02 radians=1.1◦. At this production rate, the currently available early Belle II data, which have an integrated luminosity of only 472pb−1, are likely not large enough for a meaningful KL calibration, however, Belle II is expected to produce 50ab−1 of integrated luminosity. As Belle II produces more data this method will become more and more feasible.

The high design luminosity of the SuperKEKB electron-positron collider is expected to result in challenging levels of beam-induced backgrounds in the interaction region. Properly simulating and mitigating these backgrounds is critical to the success of the Belle~II experiment. We report on measurements performed with a suite of dedicated beam background detectors, collectively known as BEAST II, during the so-called Phase 1 commissioning run of SuperKEKB in 2016, which involved operation of both the high energy ring (HER) of 7 GeV electrons as well as the low energy ring (LER) of 4 GeV positrons. We describe the BEAST II detector systems, the simulation of beam backgrounds, and the measurements performed. The measurements include standard ones of dose rates versus accelerator conditions, and more novel investigations, such as bunch-by-bunch measurements of injection backgrounds and measurements sensitive to the energy spectrum and angular distribution of fast neutrons. We observe beam-gas, Touschek, beam-dust, and injection backgrounds. We do not observe significant synchrotron radiation, as expected. Measured LER beam-gas backgrounds and Touschek backgrounds in both rings are slightly elevated, on average three times larger than the levels predicted by simulation. HER beam-gas backgrounds are on on average two orders of magnitude larger than predicted. Systematic uncertainties and channel-to-channel variations are large, so that these excesses constitute only 1-2 sigma level effects. Neutron background rates are higher than predicted and should be studied further. We will measure the remaining beam background processes, due to colliding beams, in the imminent commissioning Phase 2. These backgrounds are expected to be the most critical for Belle II, to the point of necessitating replacement of detector components during the Phase 3 (full-luminosity) operation of SuperKEB., 101 pages, 127 figures

Using a data sample of 921.9 fb(-1) collected with the Belle detector, we study the process of e(+)e(-)-> Ds+Ds1(2536)(-) + c.c. via initial-state radiation. We report the first observation of a vector charmoniumlike state decaying to Ds+Ds1(2536)(-) + c.c. with a significance of 5.9 sigma, including systematic uncertainties. The measured mass and width are (4625.9(-6.0)(+6.2)(stat)+/- 0.4(syst))MeV/c(2) and (49.8(-11.5)(+13.9)(stat) +/- 4.0(syst)) MeV, respectively. The product of the e(+)e(-)-> Ds+Ds1(2536)(-) + c.c. cross section and the branching fraction of D-s1 (2536)(-) ->( D) over bar *0K(-) is measured from the D-s(D) over bar (s1) (2536) threshold to 5.59 GeV. We thank the KEKB group for the excellent operation of the accelerator; the KEK cryogenics group for the efficient operation of the solenoid; and the KEK computer group, and the Pacific Northwest National Laboratory (PNNL) Environmental Molecular Sciences Laboratory (EMSL) computing group for strong computing support; and the National Institute of Informatics, and Science Information NETwork 5 (SINET5) for valuable network support. We acknowledge support from the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) of Japan, the Japan Society for the Promotion of Science (JSPS), and the Tau-Lepton Physics Research Center of Nagoya University; the Australian Research Council including Grants No. DP180102629, No. DP170102389, No. DP170102204, No. DP150103061, and No. FT130100303; Austrian Science Fund (FWF); the National Natural Science Foundation of China under Contracts No. 11435013, No. 11475187, No. 11521505, No. 11575017, No. 11675166, No. 11705209, No. 11761141009, No. 11975076; Key Research Program of Frontier Sciences, Chinese Academy of Sciences (CAS), Grant No. QYZDJ-SSW-SLH011; the CAS Center for Excellence in Particle Physics (CCEPP); the Shanghai Pujiang Program under Grant No. 18PJ1401000; the Ministry of Education, Youth and Sports of the Czech Republic under Contract No. LTT17020; the Carl Zeiss Foundation, the Deutsche Forschungsgemeinschaft, the Excellence Cluster Universe, and the VolkswagenStiftung; the Department of Science and Technology of India; the Istituto Nazionale di Fisica Nucleare of Italy; National Research Foundation (NRF) of Korea Grants No. 2016R1-D1A1B-01010135, No. 2016R1-D1A1B-02012900, No. 2018R1-A2B-3003643, No. 2018R1-A6A1A-06024970, No. 2018R1-D1A1B-07047294, No. 2019K1-A3A7A-09033840, and No. 2019R1-I1A3A-01058933; Radiation Science Research Institute, Foreign Large-size Research Facility Application Supporting project, the Global Science Experimental Data Hub Center of the Korea Institute of Science and Technology Information and KREONET/GLORIAD; the Polish Ministry of Science and Higher Education and the National Science Center; the Ministry of Science and Higher Education of the Russian Federation, Agreement 14.W03.31.0026; from 15.02.2018; the Slovenian Research Agency; Ikerbasque, Basque Foundation for Science, Spain; the Swiss National Science Foundation; the Ministry of Education and the Ministry of Science and Technology of Taiwan; and the United States Department of Energy and the National Science Foundation.

Using a data sample of 921.9 fb$^{-1}$ collected with the Belle detector, we study the process of $e^+e^-\to D^+_sD_{s1}(2536)^-+c.c.$ via initial-state radiation. We report the first observation of a vector charmoniumlike state decaying to $D^+_sD_{s1}(2536)^-+c.c.$ with a significance of 5.9$\sigma$, including the systematic uncertainties. The measured mass and width are $(4625.9^{+6.2}_{-6.0}({\rm stat.})\pm0.4({\rm syst.}))~{\rm MeV}/c^{2}$ and $(49.8^{+13.9}_{-11.5}({\rm stat.})\pm4.0({\rm syst.}))~{\rm MeV}$, respectively. The product of the $e^+e^-\to D^+_sD_{s1}(2536)^-+c.c.$ cross section and the branching fraction of $D_{s1}(2536)^-\to{\bar D}^{*0}K^-$ is measured from the $D_s \bar{D}_{s1}(2536)$ threshold to 5.59~GeV., Comment: 8 pages, 3 figures, plus 2 pages Supplemental Material

Recently, the Belle Collaboration has updated the analysis of the cross sections for the processes $e^+ e^- \to \Upsilon(nS)\, \pi^+ \pi^-$ ($n = 1,\, 2,\, 3$) in the $e^+ e^-$ center-of-mass energy range from 10.52 to 11.02 GeV. A new structure, called here $Y_b (10750)$, with the mass $M (Y_b) = (10752.7 \pm 5.9^{+0.7}_{-1.1})$ MeV and the Breit-Wigner width $\Gamma (Y_b) = (35.5^{+17.6 +3.9}_{-11.3 -3.3})$ MeV was observed \cite{Abdesselam:2019gth}. We interpret $Y_b (10750)$ as a compact $J^{PC} = 1^{--}$ state with a dominant tetraquark component. The mass eigenstate $Y_b (10750)$ is treated as a linear combination of the diquark-antidiquark and $b \bar b$ components due to the mixing via gluonic exchanges shown recently to arise in the limit of large number of quark colors. The mixing angle between $Y_b$ and $\Upsilon(5S)$ can be estimated from the electronic width, recently determined to be $\Gamma_{ee} (Y_b) = (13.7 \pm 1.8)$ eV. The mixing provides a plausible mechanism for $Y_b (10750)$ production in high energy collisions from its $b \bar b$ component and we work out the Drell-Yan and prompt production cross sections for $p p \to Y_b (10750) \to \Upsilon (nS)\, \pi^+ \pi^-$ at the LHC. The resonant part of the dipion invariant mass spectrum in $Y_b (10750) \to \Upsilon (1S)\, \pi^+ \pi^-$ and the corresponding angular distribution of $\pi^+$-meson in the dipion rest frame are presented as an example., Comment: 6 pages, 3 figures; v2: some numerics updated based on new results for $\Gamma_{ee}(Y_b)$, references added; v3: accept by Physics Letters B

Precise measurements of B meson decays are important to test the flavour sector of the Standard Model and to search for New Physics. New Physics models predict contributions beyond the Standard Model that may change observables like branching fractions by a measurable amount. For instance, a new charged current, as for example predicted in two-Higgs-Doublet-Models, can occur in tree-level as well as in loop or box diagrams and interfere with the weak charged current of the Standard Model. The Belle experiment collected a dataset of 977 fb-1, mainly recorded at the ϒ(4S) resonance, and provides an excellent environment to study decays of B and Bs mesons. We discuss measurements of the branching fractions of the tree level decays B→τν and B→D(⁎)τν. In addition, we measure the forward-backward asymmetry in the inclusive decay B→Xsl+l− and search for a significant, New Physics induced, time-dependent CP violation in B→ηKSγ. The branching fraction of Bs→ϕγ is measured and searches for Bs→γγ and further, a Dark Photon from a secluded sector are carried out on.

Recent results related to baryon productions with the full data set collected by Belle or BaBar are shown. These include inclusive antideuteron production at ϒ ( n S ) , branching fraction measurement of Λ c + → p K − π + , precision measurements of the masses and widths of Σ c ( 2455 ) 0 / + + and Σ c ( 2520 ) 0 / + + , searches for doubly charmed baryons/charmed strange baryons, and exclusive Λ Λ ‾ production at ϒ ( 1 S , 2 S ) .

These proceedings cover recent measurements of rare charmless decays B + → K ‾ ⁎ ( 892 ) 0 K ⁎ ( 892 ) + , B 0 → η ′ K ⁎ ( 892 ) 0 and B 0 → π 0 π 0 with a data sample of 772 × 10 6 B B ‾ pairs collected at the ϒ ( 4 S ) resonance with the Belle detector at the KEKB asymmetric-energy e + e − collider. In the decay channel B + → K ‾ ⁎ ( 892 ) 0 K ⁎ ( 892 ) + an excess of 2.73σ is observed, which corresponds to B = ( 0.77 − 0.30 + 0.35 ± 0.12 ) × 10 − 6 and a longitudinal polarization f L = 1.06 ± 0.30 ± 0.14 . A signal strength of 5.0σ is measured in the decay channel B 0 → η ′ K ⁎ ( 892 ) 0 with the corresponding B = ( 2.6 ± 0.7 ± 0.2 ) × 10 − 6 and a CP asymmetry of A C P = − 0.22 ± 0.29 ± 0.07 . Finally we report an updated measurement of B 0 → π 0 π 0 decays, with a measured branching fraction of B = ( 0.90 ± 0.12 ± 0.10 ) × 10 − 6 .

We present γ / ϕ 3 measurements that use Dalitz analysis and the relevant updates with ADS and GLW method from Belle experiment at the KEKB asymmetric energy collider of 3.5 GeV positron and 8.5 GeV electron, in Japan. The combined value of the γ / ϕ 3 with GLW + ADS and Dalitz results is γ / ϕ 3 = 73 − 15 + 13 [ ° ] .

We present the recent measurements of the B 0 → η ′ K 0 and the B → ω K decay modes based on the full data set of 772 × 10 6 B B ‾ pairs collected by the Belle detector at the KEKB e + e − collider. In the B 0 → η ′ K 0 mode, we obtain the CP-violating parameters A η ′ K 0 = + 0.03 ± 0.05 (stat) ± 0.04 (syst), S η ′ K 0 = + 0.68 ± 0.07 (stat) ± 0.03 (syst). This is the world's most precise result on the η ′ K 0 CP parameters. In B → ω K decays, we measure the branching fractions B B 0 → ω K 0 = ( 4.5 ± 0.4 (stat) ± 0.3 (syst) ) × 10 − 6 , B B − → ω K − = ( 6.8 ± 0.4 (stat) ± 0.4 (syst) ) × 10 − 6 , which are their current most precise results. We measure the first evidence of CP violation in the B 0 → ω K S 0 decay mode, obtaining the CP-violating parameters A ω K S 0 = − 0.36 ± 0.19 (stat) ± 0.05 (syst) , S ω K S 0 = + 0.91 ± 0.32 (stat) ± 0.05 (syst) . In the B − → ω K − mode, we measure the direct CP-violation parameter A ω K − = − 0.03 ± 0.04 (stat) ± 0.01 (syst) , which is its most precise measurement to date.

International audience; Belle II detector upgrade is being discussed aiming to collect five times larger integrated luminosity of 250 ab−1. The beam background level is expected five times higher than current design, thus a new pixel vertex detector with faster readout should be developed. We have invented a new pixel detector concept DuTiP for the Belle II upgrade which can be also used for the International Linear Collider (ILC) with small modifications. To realize the DuTiP concept, an SOI technology is chosen as a baseline with a pixel size of 35μm×35μm. The DuTiP concept and its application to a monolithic pixel detector in an SOI technology are explained.

International audience; The aerogel Ring Imaging CHerenkov counter (ARICH) is the particle identification device installed in the forward region of the Belle II detector at the SuperKEKB accelerator facility in Japan. The first electron–positron collisions at SuperKEKB took place on April 26, 2018, during the so called phase 2 run. The measured performance of the detector based on recorded Bhabha events during phase 2 is presented. We measure a 14 mrad average angular resolution per photon and 10 photons per Bhabha electron in the [6–8] GeV/c momentum range.

The Belle II detector located in Tsukuba, Japan, building on the work of its predecessor Belle, is scheduled for long-term data collection from electron-positron e+e- collisions commencing in early 2019, for the purpose of studying rare B-meson decays in the search for new physics beyond the Standard Model. The Belle II Analysis Software Framework (BASF2) has been developed for physics analyses, with the Full Event Interpretation (FEI) being one such method designed for the reconstruction of B-meson decays from detector information. The FEI must be trained on simulated Monte Carlo (MC) data and introduces a signal-specific training process that can be tailored for a particular decay of interest in an attempt to increase the performance over signal-independent training processes such as those employed in Full Reconstruction (FR) methods at Belle. This study investigates the performance of the signal-specific and signal-independent FEI algorithms in the context of rare semi-leptonic B-meson decays, in comparison to leptonic decays, with the respective modes B+→ρ0 µ+ νµ and B+ → τ+ ντ chosen as working examples. The relative performance of the FEI methods implemented is evaluated via a number of key performance indicators including the reconstruction efficiency and purity of the reconstructed ϒ(4S) event.

We report the first observation of the hadronic transition Upsilon(4S) -> eta'Upsilon(1S), using 496 fb(-1) data collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We reconstruct the eta' meson through its decays to rho(0)Upsilon and to pi(+)pi(-)eta, with eta -> gamma gamma. We measure B(Upsilon(4S) -> eta'Upsilon(1S)) = [3.43 +/- 0.88(stat) +/- 0.21(syst)] x 10(-5), with a significance of 5.7 sigma. We thank the KEKB group for excellent operation of the accelerator; the KEK cryogenics group for efficient solenoid operations; and the KEK computer group, the NII, and Pacific Northwest National Laboratory (PNNL)/Environmental Molecular Sciences Laboratory (EMSL) for valuable computing and Science Information NETwork 5 (SINET5) network support. We acknowledge support from Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan Society for the Promotion of Science (JSPS), and Nagoya's TLPRC (Japan); Australian Research Council (ARC) (Australia); FWF (Austria); National Natural Science Foundation of China (NSFC) and CAS Center for Excellence in Particle Physics (CCEPP) (China); MSMT (Czechia); CZF, Deutsche Forschungsgemeinschaft (DFG), EXC153, and VS (Germany); DST (India); Instituto Nazionale di Fisica Nucleare (INFN) (Italy); Ministry of Education (MOE), Ministry of Science, ICT and Future Planning (MSIP), National Research Foundation (NRF), RSRI, FLRFAS project, and GSDC of Korea Institute of Science and Technology Information (KISTI) (Korea); Ministerstwo Nauki i Szkolnictwa Wyzszego (MNiSW) and Narodowe Centrum Nauki (NCN) (Poland); MES under Contract No. 14.W03.31.0026 (Russia); ARRS (Slovenia); IKERBASQUE and Ministry of Economy and Competitiveness (MINECO) (Spain); SNSF (Switzerland); Ministry of Education (MOE) and Ministry of Science and Technology, Taiwan (MOST) (Taiwan); and U.S. Department of Energy (DOE) and National Science Foundation (NSF) (USA).

We report the result from the first search for $D^0$ decays to invisible final states. The analysis is performed on a data sample of 924 $\rm{fb}^{-1}$ collected at and near the $\Upsilon(4S)$ and $\Upsilon(5S)$ resonances with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. The absolute branching fraction is determined using an inclusive $D^0$ sample, obtained by fully reconstructing the rest of the particle system including the other charmed particle. No significant signal yield is observed and an upper limit of $9.4\times 10^{-5}$ is set on the branching fraction of $D^0$ to invisible final states at 90\% confidence level., Comment: 17 pages, 4 figures, submitted to PRD(RC)