Records |
Author |
Belle-II DEPFET and PXD Collaborations (Ahlburg, P. et al); Marinas, C. |
Title |
The new and complete Belle II DEPFET pixel detector: Commissioning and previous operational experience |
Type |
Journal Article |
Year |
2024 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
Volume |
1068 |
Issue |
|
Pages |
169763 - 6pp |
Keywords |
Belle II; DEPFET; Pixel detector; Vertex detector |
Abstract |
The Belle II experiment at the SuperKEKB collider in Tsukuba, Japan, has collected e+e- + e – collision data between 2019 and 2022. After reaching a record-breaking instantaneous luminosity of 4.71x1034 . 71x10 34 cm -2 s -1 and recording a dataset corresponding to 424 fb -1 , it completed its first planned long shutdown phase in December 2023. Aside from upgrades of the collider and detector maintenance, the shutdown was used for the installation of the two-layer Pixel VerteX Detector (PXD). As the innermost sub-detector, multiple scattering effects need to be reduced. PXD utilizes the Depleted P-channel Field Effect Transistor (DEPFET) technology, allowing for a material budget of 0.21% X0 0 per layer. Each of the tracker's 40 modules consists of an array of 250x768 pixels with a pitch ranging from 50 μmx 55 μm for the inner to 85 μmx 55 μm for the outer layer yielding high gain and high signal-to-noise ratio while retaining about 99% hit efficiency. This article discusses the experience of the 4-year operation of the previous single-layer PXD in harsh background conditions as well as commissioning and testing of the fully-populated PXD2 during Long Shutdown 1. |
Address |
[Ahlburg, P.; Bernlochner, F.; Dingfelder, J.; Farkas, R.; Giakoustidis, G.; Khan, M.; Krueger, H.; Paschen, B.; Schmitz, J.; Wermes, N.] Univ Bonn, D-53115 Bonn, Germany, Email: jannes.schmitz@uni-bonn.de |
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Elsevier |
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English |
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ISSN |
0168-9002 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:001306604900001 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
6252 |
Permanent link to this record |
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Author |
Babeluk, M. et al; Lacasta, C.; Marinas, C.; Mazorra de Cos, J.; Vobbilisetti, V. |
Title |
The OBELIX chip for the Belle II VTX upgrade |
Type |
Journal Article |
Year |
2024 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
Volume |
1067 |
Issue |
|
Pages |
169659 - 3pp |
Keywords |
Belle II; Belle II VTX; CMOS Pixel Sensor; Depleted Monolithic Active Pixel Sensor; DMAPS; Vertex detector; Particle tracking detectors; Radiation-hard detectors; OBELIX; Trigger |
Abstract |
The OBELIX depleted monolithic active CMOS pixel sensor (DMAPS) is currently developed for the upgrade of the vertex detector of the Belle II experiment located at Tsukuba/Japan. The pixel matrix of OBELIX is inherited from the TJ-Monopix2 chip, but the periphery includes additional features to improve performance and allow the integration into a larger detector system. The new features include a trigger unit to process trigger signals, a precision timing module and a possibility to transmit low granularity hit information with low latency to contribute to the Belle II trigger. Additionally, low dropout voltage regulators and an ADC to monitor power consumption and substrate temperature is developed. This paper will focus on the trigger contribution capabilities of the OBELIX chip. |
Address |
[Babeluk, M.; Bergauer, T.; Irmler, C.; Kaliyar, A. B.; Pilsl, B.; Schwanda, C.] Austrian Acad Sci, Inst High Energy Phys, Nikolsdorfer Gasse 18, Vienna, Austria, Email: maximilian.babeluk@oeaw.ac.at |
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Elsevier |
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English |
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ISSN |
0168-9002 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:001296113100001 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
6248 |
Permanent link to this record |
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Author |
Belle II VTX Collaboration (Babeluk, M. et al).; Marinas, C.; Mazorra de Cos, J. |
Title |
The DMAPS upgrade of the Belle II vertex detector |
Type |
Journal Article |
Year |
2024 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
Volume |
1064 |
Issue |
|
Pages |
169428 - 5pp |
Keywords |
Belle II; Belle II VTX; CMOS Pixel Sensor; Depleted Monolithic Active Pixel Sensor; DMAPS; Vertex detector; Radiation damage; Particle tracking detectors; Radiation-hard detectors |
Abstract |
The Belle II experiment at KEK in Japan considers an upgrade for the vertex detector system in line with the accelerator upgrade for higher luminosity at long shutdown 2 planned for 2028. One proposal for the upgrade of the vertex detector called VTX aims to improve background robustness and reduce occupancy using small and fast pixels. VTX accommodates the OBELIX depleted monolithic active CMOS pixel sensor (DMAPS) on all five proposed layers. OBELIX is specifically developed for the VTX application and based on the TJ-Monopix2 chip initially developed to meet the requirements of the outer layers of the ATLAS inner tracker (ITk). This paper will review recent tests of the TJ-Monopix2 chip as well as various design aspects of the OBELIX-1 chip currently under development. |
Address |
[Babeluk, M.; Bergauer, T.; Finck, C.; Irmler, C.] Austrian Acad Sci, Inst High Energy Phys, A-1050 Vienna, Austria, Email: maximilian.babeluk@oeaw.ac.at |
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Thesis |
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Elsevier |
Place of Publication |
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English |
Summary Language |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0168-9002 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:001304265000001 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
6246 |
Permanent link to this record |
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Author |
Natochii, A. et al; Marinas, C. |
Title |
Measured and projected beam backgrounds in the Belle II experiment at the SuperKEKB collider |
Type |
Journal Article |
Year |
2023 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
Volume |
1055 |
Issue |
|
Pages |
168550 - 21pp |
Keywords |
Detector background; Lepton collider; Monte-Carlo simulation |
Abstract |
The Belle II experiment at the SuperKEKB electron-positron collider aims to collect an unprecedented data set of 50 ab-1 to study CP-violation in the B-meson system and to search for Physics beyond the Standard Model. SuperKEKB is already the world's highest-luminosity collider. In order to collect the planned data set within approximately one decade, the target is to reach a peak luminosity of 6 x 1035 cm-2 s-1by further increasing the beam currents and reducing the beam size at the interaction point by squeezing the betatron function down to betay* = 0.3 mm. To ensure detector longevity and maintain good reconstruction performance, beam backgrounds must remain well controlled. We report on current background rates in Belle II and compare these against simulation. We find that a number of recent refinements have significantly improved the background simulation accuracy. Finally, we estimate the safety margins going forward. We predict that backgrounds should remain high but acceptable until a luminosity of at least 2.8 x 1035 cm-2 s-1is reached for betay* = 0.6 mm. At this point, the most vulnerable Belle II detectors, the Time-of-Propagation (TOP) particle identification system and the Central Drift Chamber (CDC), have predicted background hit rates from single-beam and luminosity backgrounds that add up to approximately half of the maximum acceptable rates. |
Address |
[Natochii, A.; Browder, T. E.; Schueler, J.; Vahsen, S. E.] Univ Hawaii, Honolulu, HI 96822 USA, Email: natochii@hawaii.edu; |
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Elsevier |
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English |
Summary Language |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0168-9002 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:001056103200001 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
5626 |
Permanent link to this record |
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Author |
Babeluk, M. et al; Marinas, C. |
Title |
CMOS MAPS upgrade for the Belle II Vertex Detector |
Type |
Journal Article |
Year |
2023 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
Volume |
1048 |
Issue |
|
Pages |
168015 - 5pp |
Keywords |
Belle II; VXD; SVD; PXD; VTX; Upgrade; CMOS; DMAPS |
Abstract |
The success of the Belle II experiment in Japan relies on the very high instantaneous luminosity, close to 6x1035 cm-2 s-1, expected from the SuperKEKB collider. The corresponding beam conditions at such luminosity levels generate large rates of background particles and creates stringent constraints on the vertex detector, adding to the physics requirements. Current prospects for the occupancy rates in the present vertex detector (VXD) at full luminosity fall close to the acceptable limits and bear large uncertainties. In this context, the Belle II collaboration is considering the possibility to install an upgraded VXD system around 2027 to provide a sufficient safety margin with respect to the expected background rate and possibly enhance tracking and vertexing performance. The VTX collaboration has started the design of a fully pixelated VXD, called VTX, based on fast and highly granular Depleted Monolithic Active Pixel Sensors (DMAPS) integrated on light support structures. The two main technical features of the VTX proposal are the usage of a single sensor type over all the layers of the system and the overall material budget below 2% of radiation length, compared to the current VXD which has two different sensor technologies and about 3% of radiation length. A dedicated sensor (OBELIX), taylored to the specific needs of Belle II, is under development, evolving from the existing TJ-Monopix2 sensor. The time-stamping precision below 100 ns will allow all VTX layers to take part in the track finding strategy contrary to the current situation. The first two detection layers are designed according to a self-supported all-silicon ladder concept, where 4 contiguous sensors are diced out of a wafer, thinned and interconnected with post-processed redistribution layers. The outermost detection layers follow a more conventional approach with a cold plate and carbon fibre support structure, and light flex cables interconnecting the sensors. This document will review the context, technical details and development status of the proposed Belle II VTX. |
Address |
[Babeluk, M.; Bergauer, T.; Irmler, C.; Schwanda, C.] Austrian Acad Sci, Inst High Energy Phys, A-1050 Vienna, Austria, Email: christian.wessel@desy.de |
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Publisher |
Elsevier |
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English |
Summary Language |
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Original Title |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0168-9002 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000990246200001 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
5538 |
Permanent link to this record |
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Author |
Liptak, Z. et al; Marinas, C. |
Title |
Measurements of beam backgrounds in SuperKEKB Phase 2 |
Type |
Journal Article |
Year |
2022 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
Volume |
1040 |
Issue |
|
Pages |
167168 - 19pp |
Keywords |
|
Abstract |
The high design luminosity of the SuperKEKB electron–positron collider will result in challenging levels of beam-induced backgrounds in the interaction region. Understanding and mitigating these backgrounds is critical to the success of the Belle II experiment. We report on the first background measurements performed after roll-in of the Belle II detector, a period known as SuperKEKB Phase 2, utilizing both the BEAST II system of dedicated background detectors and the Belle II detector itself. We also report on first revisions to the background simulation made in response to our findings. Backgrounds measured include contributions from synchrotron radiation, beam-gas, Touschek, and injection backgrounds. At the end of Phase 2, single-beam backgrounds originating from the 4 GeV positron Low Energy Ring (LER) agree reasonably well with simulation, while backgrounds from the 7 GeV electron High Energy Ring (HER) are approximately one order of magnitude higher than simulation. We extrapolate these backgrounds forward and conclude it is safe to install the Belle II vertex detector. |
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Area |
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Notes |
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Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
5496 |
Permanent link to this record |
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Author |
Belle-II DEPFET and PXD Collaborations (Wang, B. et al); Marinas, C. |
Title |
Operational experience of the Belle II pixel detector |
Type |
Journal Article |
Year |
2022 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
Volume |
1032 |
Issue |
|
Pages |
166631 - 7pp |
Keywords |
Belle II PXD; DEPFET; Pixel detector; Vertex detector |
Abstract |
The Belle II experiment at the SuperKEKB accelerator has started its physics data taking with the full detector setup in March 2019. It aims to collect 40 times more e+e- collision data compared with its predecessor Belle experiment. The Belle II pixel detector (PXD) is based on the Depleted P-channel Field Effect Transistor (DEPFET) technology. The PXD plays an important role in the tracking and vertexing of the Belle II detector. Its two layers are arranged at radii of 14 mm and 22 mm around the interaction point. The sensors are thinned down to 75 μm to minimize multiple scattering, and each module has interconnects and ASICs integrated on the sensor with silicon frames for mechanical support. PXD showed good performance during data taking. It also faces several operational challenges due to the high background level from the SuperKEKB accelerator, such as the damage from beam loss events, the drift in the HV working point due to radiation effect, and the impact of the high background. |
Address |
[Alonso, O.; Dieguez, A.] Univ Barcelona, C Marti Franques 1, Barcelona 08028, Spain, Email: wang@mpp.mpg.de |
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Elsevier |
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English |
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ISSN |
0168-9002 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000793768200001 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
5227 |
Permanent link to this record |
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Author |
Belle II Collaboration (Abudinen, F. et al); Marinas, C. |
Title |
B-flavor tagging at Belle II |
Type |
Journal Article |
Year |
2022 |
Publication |
European Physical Journal C |
Abbreviated Journal |
Eur. Phys. J. C |
Volume |
82 |
Issue |
4 |
Pages |
283 - 29pp |
Keywords |
|
Abstract |
We report on new flavor tagging algorithms developed to determine the quark-flavor content of bottom (B) mesons at Belle II. The algorithms provide essential inputs for measurements of quark-flavor mixing and charge-parity violation. We validate and evaluate the performance of the algorithms using hadronic B decays with flavor-specific final states reconstructed in a data set corresponding to an integrated luminosity of 62.8 fb(-1), collected at the gamma(4S) resonance with the Belle II detector at the SuperKEKB collider. We measure the total effective tagging efficiency to be epsilon(eff) = (30.0 +/- 1.2(stat) +/- 0.4(syst))% for a category-based algorithm and epsilon(eff) = (28.8 +/- 1.2(stat) +/- 0.4(syst))% for a deep-learning-based algorithm. |
Address |
[Lautenbach, K.; Zani, L.] Aix Marseille Univ, CPPM, CNRS IN2P3, F-13288 Marseille, France |
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Publisher |
Springer |
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English |
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Series Issue |
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Edition |
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ISSN |
1434-6044 |
ISBN |
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Conference |
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Notes |
WOS:000777159100005 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
5188 |
Permanent link to this record |
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Author |
Belle II Collaboration (Abudinen, F. et al); Marinas, C. |
Title |
Precise Measurement of the D-0 and D+ Lifetimes at Belle II |
Type |
Journal Article |
Year |
2021 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
Volume |
127 |
Issue |
21 |
Pages |
211801 - 9pp |
Keywords |
|
Abstract |
We report a measurement of the D-0 and D+ lifetimes using D-0 -> K-pi(+) and D+ -> K-pi(+)pi(+) decays reconstructed in e(+)e(-) -> c (c) over bar data recorded by the Belle II experiment at the SuperKEKB asymmetric-energy e(+)e(-) collider. The data, collected at center-of-mass energies at or near the (sic)(4S) resonance, correspond to an integrated luminosity of 72 fb(-1). The results, (tau)(D-0) = 410.5 +/- 1.1 (stat) +/- 0.8(syst) fs and tau(D-0) = 1030.4 +/- 4.7 (stat) +/- 3.1 (syst) fs, are the most precise to date and are consistent with previous determinations. |
Address |
[Lautenbach, K.; Polat, G.; Serrano, J.; Zani, L.] Aix Marseille Univ, CPPM, CNRS IN2P3, F-13288 Marseille, France |
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Publisher |
Amer Physical Soc |
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English |
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Edition |
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ISSN |
0031-9007 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000721613700003 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
5032 |
Permanent link to this record |
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Author |
Belle II Collaboration (Abudinen, F. et al); Marinas, C. |
Title |
Search for B+ -> K+nu(nu)over-bar Decays Using an Inclusive Tagging Method at Belle H |
Type |
Journal Article |
Year |
2021 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys. Rev. Lett. |
Volume |
127 |
Issue |
18 |
Pages |
181802 - 10pp |
Keywords |
|
Abstract |
A search for the flavor-changing neutral-current decay B+ -> K+nu(nu) over bar is performed at the Belle II experiment at the SuperKEKB asymmetric energy electron-positron collider. The data sample corresponds to an integrated luminosity of 63 fb(-1) collected at the Upsilon(4S) resonance and a sample of 9 fb(-1) collected at an energy 60 MeV below the resonance. Because the measurable decay signature involves only a single charged kaon, a novel measurement approach is used that exploits not only the properties of the B+ -> K+nu(nu) over bar decay, but also the inclusive properties of the other B meson in the Upsilon(4S) -> B (B) over bar event, to suppress the background from other B meson decays and light-quark pair production. This inclusive tagging approach offers a higher signal efficiency compared to previous searches. No significant signal is observed. An upper limit on the branching fraction of B+ -> K+nu(nu) over bar of 4.1 x 10(-5) is set at the 90% confidence level. |
Address |
[Lautenbach, K.; Polat, G.; Serrano, J.; Zani, L.] Aix Marseille Univ, CPPM, CNRS IN2P3, F-13288 Marseille, France |
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Publisher |
Amer Physical Soc |
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English |
Summary Language |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0031-9007 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000712526000010 |
Approved |
no |
Is ISI |
yes |
International Collaboration |
yes |
Call Number |
IFIC @ pastor @ |
Serial |
5020 |
Permanent link to this record |