111 research outputs found
Dynamic walking stability of the TUlip robot by means of the extrapolated center of mass
The TUlip robot was created to participate in the teensize league of Robocup. The TUlip robot is a bipedal robot intended for dynamic walking. It has six degrees of freedom for each leg: three for the hip, one for the knee and two for the ankle. This paper elaborates on the algorithm for the sideways control during gait. The algorithm uses the extrapolated center of mass (XcoM) to achieve limit cycle stability. The algorithm is tested in simulation using a linear inverted pendulum and, then, experimentally applied to the TUlip robot. The result is an adaptive behavior of the TUlip robot, promising for future application to legged robot stability
Measured and projected beam backgrounds in the Belle II experiment at the SuperKEKB collider
The Belle II experiment at the SuperKEKB electron-positron collider aims to
collect an unprecedented data set of to study -violation
in the -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 by further
increasing the beam currents and reducing the beam size at the interaction
point by squeezing the betatron function down to . 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 is reached for
. 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.Comment: 28 pages, 17 figures, 9 tables (revised
Belle II Vertex Detector Performance
The Belle II experiment at the SuperKEKB accelerator (KEK, Tsukuba, Japan) collected its first e+e− collision data in the spring 2019. The aim of accumulating a 50 times larger data sample than Belle at KEKB, a first generation B-Factory, presents substantial challenges to both the collider and the detector, requiring not only state-of-the-art hardware, but also modern software algorithms for tracking and alignment.
The broad physics program requires excellent performance of the vertex detector, which is composed of two layers of DEPFET pixels and four layers of double sided-strip sensors. In this contribution, an overview of the vertex detector of Belle II and our methods to ensure its optimal performance, are described, and the first results and experiences from the first physics run are presented
Search for Axionlike Particles Produced in e⁺ e⁻ Collisions at Belle II
International audienceWe present a search for the direct production of a light pseudoscalar a decaying into two photons with the Belle II detector at the SuperKEKB collider. We search for the process e+e-→γa, a→γγ in the mass range 0.2
Search for Axionlike Particles Produced in e+e- Collisions at Belle II
We present a search for the direct production of a light pseudoscalar a decaying into two photons with the Belle II detector at the SuperKEKB collider. We search for the process e+e-→γa, a→γγ in the mass range 0.2<9.7 GeV/c2 using data corresponding to an integrated luminosity of (445±3) pb-1. Light pseudoscalars interacting predominantly with standard model gauge bosons (so-called axionlike particles or ALPs) are frequently postulated in extensions of the standard model. We find no evidence for ALPs and set 95% confidence level upper limits on the coupling strength gaγγ of ALPs to photons at the level of 10-3 GeV-1. The limits are the most restrictive to date for 0.2<1 GeV/c2
Search for an Invisibly Decaying Z\u27 Boson at Belle II in e⁺e⁻ → μ⁺μ⁻(eμ) Plus Missing Energy Final States
Financial Systems and Industrial Policy in Germany and Great Britain: The Limits of Convergence
Measurement of the integrated luminosity of the Phase 2 data of the Belle II experiment
From April to July 2018, a data sample at the peak energy of the γ(4S) resonance was collected with the Belle II detector at the SuperKEKB electron-positron collider. This is the first data sample of the Belle II experiment. Using Bhabha and digamma events, we measure the integrated luminosity of the data sample to be (496.3 ± 0.3 ± 3.0) pb-1, where the first uncertainty is statistical and the second is systematic. This work provides a basis for future luminosity measurements at Belle II
Observation of decays using the 2019-2022 Belle II data sample
We present a measurement of the branching fractions of four decay modes. The measurement is based on data from
SuperKEKB electron-positron collisions at the resonance
collected with the Belle II detector and corresponding to an integrated
luminosity of . The event yields are extracted from fits
to the distributions of the difference between expected and observed meson
energy to separate signal and background, and are efficiency-corrected as a
function of the invariant mass of the system. We find the branching
fractions to be: where the first uncertainty is statistical and
the second systematic. These results include the first observation of
, , and decays and a significant improvement in the precision
of compared to previous measurements
- …