B-flavor tagging at Belle II Akopov, N.; Banerjee, Sw; Bauer, M. ...
The European physical journal. C, Particles and fields,
04/2022, Letnik:
82, Številka:
4
Journal Article
Recenzirano
Odprti dostop
We report on new flavor tagging algorithms developed to determine the quark-flavor content of bottom (
) 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
decays with flavor-specific final states reconstructed in a data set corresponding to an integrated luminosity of 62.8 fb
-
1
, collected at the
resonance with the Belle II detector at the SuperKEKB collider. We measure the total effective tagging efficiency to be
ε
eff
=
(
30.0
±
1.2
(
stat
)
±
0.4
(
syst
)
)
%
for a category-based algorithm and
ε
eff
=
(
28.8
±
1.2
(
stat
)
±
0.4
(
syst
)
)
%
for a deep-learning-based algorithm.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The Belle II experiment is a new generation B-factory experiment at KEK in Japan aiming at the search for New Physics in a huge sample of B-meson decays. The commissioning of the accelerator and the ...detector for the first physics run has started from March this year. The Belle II High Level Trigger (HLT) is fully working in the beam run. The HLT is now operated with 1600 cores clusterized in 5 units, which is 1/4 of the full configuration. The software trigger is performed using the same o
ffl
ine reconstruction code, and events are classified into a set of physics categories. Only the events in the categories of interest are finally sent out to the storage. Live data quality monitoring is also performed on HLT. For the selected events, the reconstructed tracks are extrapolated to the surface of the pixel detector (PXD) and quickly fed back to the readout electronics for the real time data reduction by sending only the associated hits. The maximum trigger rate in the first physics run was 3.5kHz, and the Belle II data acquisition system was stably operated. There were several problems in the HLT operation, but they have successfully been fixed during the data taking period. The HLT reduction factor is measured to be 8 which is still higher than the design because of the high background environment.
The Belle II experiment at the future SuperKEKB collider in Tsukuba, Japan, features a design luminosity of 8·1035 cm−2s−1, which is a factor of 40 larger than that of its predecessor Belle. The ...pixel detector (PXD) with about 8 million pixels is based on the DEPFET technology and will improve the vertex resolution in beam direction by a factor of 2. With an estimated trigger rate of 30 kHz, the PXD is expected to generate a data rate of 20 GBytes/s, which is about 10 times larger than the amount of data generated by all other Belle II subdetectors. Due to the large beam-related background, the PXD requires a data acquisition system with high-bandwidth data links and realtime background reduction by a factor of 30. To achieve this, the Belle II pixel DAQ uses an FPGA-based computing platform with high speed serial links implemented in the ATCA (Advanced Telecommunications Computing Architecture) standard. The architecture and performance of the data acquisition system and data reduction of the PXD will be presented. In April 2016 and February 2017 a prototype PXD-DAQ system operated in a test beam campaign delivered data with the whole readout chain under realistic high rate conditions. Final results from the beam test will be presented.
At the future Belle II experiment the DEPFET (DEPleted Field Effect Transistor) pixel detector will consist of about 8 million channels and is placed as the innermost detector. The main hardware to ...reduce the data rate is a xTCA based Compute Node (CN) developed in cooperation between IHEP Beijing and University Giessen. To achieve the required data reduction on the CNs, regions of interest (ROI) are used. These regions are calculated in two independent systems by projecting tracks back to the pixel detector. One is the High Level Trigger (HLT) which uses data from the Silicon Vertex Detector (SVD), a silicon strip detector, and outer detectors. The other is the Data Concentrator (DATCON) which calculates ROIs based on SVD data only, in order to get low momentum tracks. First results of the test beam time in January 2014 at DESY with a Belle II vertex detector prototype and full DAQ chain will be presented.
infection (CDI) is the leading cause of antibiotic-associated and health care-associated diarrhea in humans. Recurrent CDI (R-CDI) occurs in ~20%-30% of patients with CDI and results in increased ...morbidity, mortality, and hospital costs. Genomic analyses have shown overlap of
isolates from animals and people, suggesting that a zoonotic reservoir may contribute to recurrence. The objective of this study was to determine whether pet ownership is a risk factor for recurrence of CDI.
We conducted a case-control study among patients with recurrent CDI (cases; n = 86) and patients with nonrecurrent CDI (controls; n = 146). Multivariable logistic regression modeling was used to determine the association between recurrence of CDI and pet ownership while accounting for patient-level risk factors.
Pet ownership was not significantly associated with recurrence of CDI (odds ratio OR, 1.02; 95% confidence interval CI, 0.38-2.72;
= 0.965) among all patients (n = 232). However, among the subset of patients with community-associated or community-onset health care facility-acquired CDI (n = 127), increasing contact with pets was increasingly protective against recurrence: for every point increase in a pet contact score (out of 7 possible points), the odds of recurrence decreased by 14% (OR, 0.86; 95% CI, 0.74-1.00;
= 0.051).
Close interactions with pets appear protective against the recurrence of community-acquired CDI. A potential mechanism may involve beneficial contributions to the microbiota of pet owners afflicted with CDI, as has been observed for other conditions such as atopy, obesity, and food allergies. However, more research is needed to understand the interactions between pets, owners, and their microbiota.
A search for the flavor-changing neutral-current decay B+→ K+νν 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 Υ(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+νν decay, but also the inclusive properties of the other B meson in the Υ(4S) → BB 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+νν of 4.1 × 10−5 is set at the 90% confidence level.
Abstract We measure CP asymmetries and branching-fraction ratios for B ± → DK ± and Dπ ± decays with D → K S 0 $$ {K}_{\textrm{S}}^0 $$ K ± π ∓, where D is a superposition of D 0 and D ¯ $$ ...\overline{D} $$ 0. We use the full data set of the Belle experiment, containing 772 × 106 B B ¯ $$ B\overline{B} $$ pairs, and data from the Belle II experiment, containing 387 × 106 B B ¯ $$ B\overline{B} $$ pairs, both collected in electron-positron collisions at the Υ(4S) resonance. Our results provide model-independent information on the unitarity triangle angle ϕ 3.
The paper presents a high-level Petri net model of concurrent systems called
predicate /transition-nets (PrT-nets). Its places represent variable properties of, or relations between, individuals; ...they are ‘predicates’ with variable extension. The transitions represent classes of elementary changes of those extensions. The model is introduced on the basis of a simple example from resource management. The central part of the paper is devoted to linear-algebraic techniques for verifying invariant assertions, yielding a calculus of
S-invariants for PrT-nets. Finally, these modelling and analysis techniques are applied to a scheme for organizing a distributed data base taken from literature.
The times spent lying down and standing by first lactation and adult cows while they were housed and while they were at pasture were studied and related during the period of housing to the incidence ...of sole lesions in first lactation cows. First lactation cows lay down for a shorter time in the early housing period than later. First lactation and adult cows lay down for longer when at pasture. Maximum lying time was significantly longer and the frequency of lying lower on pasture than indoors. The times spent lying and standing and the frequency of lying were related to the incidence of sole lesions. Rumination time was not related to the occurrence of sole lesions although there were significant variations in rumination behaviour while the animals were housed and at pasture. The patterns of lying and other activities of first lactation and adult cows while they were housed were quite different from those while they were at pasture.
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