We report a measurement of the ratio R(D*)=B($\bar{B}$0→D*+τ-$\bar{v}$$\bar{τ}$)/B($\bar{B}$0→D*+ℓ-$\bar{v}$ℓ), where ℓ denotes an electron or a muon. The results are based on a data sample ...containing 772×106 B$\bar{B}$ pairs recorded at the Υ(4S) resonance with the Belle detector at the KEKB e+e- collider. We select a sample of B0$\bar{B}$0 pairs by reconstructing both B mesons in semileptonic decays to D*∓ℓ±. We measure R(D*)=0.302±0.030(stat)±0.011(syst), which is within 1.6σ of the Standard Model theoretical expectation, where the standard deviation σ includes systematic uncertainties. We use this measurement to constrain several scenarios of new physics in a model-independent approach.
We report a measurement of the ratio R(D*) = B($\bar{B}$0→ D*+τ-$\bar{v}$τ )/B($\bar{B}$0→D*+ℓ-$\bar{v}$ℓ), where ℓ denotes an electron or a muon. The results are based on a data sample containing ...772 × 106 B$\bar{B}$ pairs recorded at the (4S) resonance with the Belle detector at the KEKB e+e- collider. We select a sample of B0 $\bar{B}$0pairs by reconstructing both B mesons in semileptonic decays to D*∓ℓ±. We measure R(D*) = 0.302±0.030(stat) ±0.011(syst), which is within 1.6σ of the Standard Model theoretical expectation, where the standard deviation σ includes systematic uncertainties. We use this measurement to constrain several scenarios of new physics in a model-independent approach.
Here, we report a measurement of the ratio R ( D* ) = B ( B ¯ 0 → D*+τ- ν ¯ τ ) / B ( B ¯ 0 → D*+ℓ- ν ¯ ℓ ) , where ℓ denotes an electron or a muon. The results are based on a data sample containing ...772×106B B ¯ pairs recorded at the Υ ( 4S ) resonance with the Belle detector at the KEKB e+e- collider. We select a sample of B0 B ¯ 0 pairs by reconstructing both B mesons in semileptonic decays to D*∓ℓ± . We measure R ( D* ) =0.302±0.030 ( stat ) ±0.011 ( syst ) , which is within 1.6σ of the Standard Model theoretical expectation, where the standard deviation σ includes systematic uncertainties. We use this measurement to constrain several scenarios of new physics in a model-independent technique.
Belle II silicon vertex detector Adamczyk, K.; Aihara, H.; Angelini, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2016, Letnik:
831
Journal Article
Recenzirano
The Belle II experiment at the SuperKEKB collider in Japan is designed to indirectly probe new physics using approximately 50 times the data recorded by its predecessor. An accurate determination of ...the decay-point position of subatomic particles such as beauty and charm hadrons as well as a precise measurement of low-momentum charged particles will play a key role in this pursuit. These will be accomplished by an inner tracking device comprising two layers of pixelated silicon detector and four layers of silicon vertex detector based on double-sided microstrip sensors. We describe herein the design, prototyping and construction efforts of the Belle-II silicon vertex detector.
Raw MgB
2
wires have been manufactured by Hyper Tech Inc. Each of their 18 cores contained undoped in situ powder surrounded by an Nb barrier and placed in a Cu sheath, and cores were coated in a ...common Monel sheath. Wires of diameters 0.63 and 0.83 mm were annealed under high argon pressure (up to 1 GPa). Parameters of such HIP process (temperature, time, and pressure) were varied in order to determine their optimal values. Superconducting properties of such samples were investigated by means of four-probe critical current j
c
measurement. Bitter magnet producing magnetic field up to 14 T was used. It provided place for samples 70 mm long in parallel field and 20 mm long in perpendicular field. Results include critical current j
c
and pinning force density F
p
dependencies on magnetic field as well as Kramer plots. Critical current of 10
4
A/cm
2
was achieved at 12 T magnetic field. SEM pictures of wire cross sections were also taken to determine quality of Nb barrier and microstructure of superconducting material.
The Belle-II VerteX Detector (VXD) has been designed to improve the performances with respect to Belle and to cope with an unprecedented luminosity of 8×1035cm−2s−1 achievable by the SuperKEKB. ...Special care is needed to monitor both the radiation dose accumulated throughout the life of the experiment and the instantaneous radiation rate, in order to be able to promptly react to sudden spikes for the purpose of protecting the detectors. A radiation monitoring and beam abort system based on single-crystal diamond sensors is now under an active development for the VXD. The sensors will be placed in several key positions in the vicinity of the interaction region. The severe space limitations require a challenging remote readout of the sensors.
A silicon vertex detector (SVD) for the Belle-II experiment comprises four layers of double-sided silicon strip detectors (DSSDs), assembled in a ladder-like structure. Each ladder module of the ...outermost SVD layer has four rectangular and one trapezoidal DSSDs supported by two carbon-fiber ribs. In order to achieve a good signal-to-noise ratio and minimize material budget, a novel chip-on-sensor “Origami” method has been employed for the three rectangular sensors that are sandwiched between the backward rectangular and forward (slanted) trapezoidal sensors. This paper describes the bonding procedures developed for making electrical connections between sensors and signal fan-out flex circuits (i.e., pitch adapters), and between pitch adapters and readout chips as well as the results in terms of the achieved bonding quality and pull force.
•Gluing and wire binding for Belle-II SVD are studied.•Gluing robot and Origami module are used.•QA are satisfied in terms of the achieved bonding throughput and the pull force.•Result will be applied for L6 ladder assembly.
Belle II SVD ladder assembly procedure and electrical qualification Adamczyk, K.; Aihara, H.; Angelini, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2016, Letnik:
824
Journal Article
Recenzirano
Odprti dostop
The Belle II experiment at the SuperKEKB asymmetric e+e− collider in Japan will operate at a luminosity approximately 50 times larger than its predecessor (Belle). At its heart lies a six-layer ...vertex detector comprising two layers of pixelated silicon detectors (PXD) and four layers of double-sided silicon microstrip detectors (SVD). One of the key measurements for Belle II is time-dependent CP violation asymmetry, which hinges on a precise charged-track vertex determination. Towards this goal, a proper assembly of the SVD components with precise alignment ought to be performed and the geometrical tolerances should be checked to fall within the design limits. We present an overview of the assembly procedure that is being followed, which includes the precision gluing of the SVD module components, wire-bonding of the various electrical components, and precision three dimensional coordinate measurements of the jigs used in assembly as well as of the final SVD modules.
We report the first measurement of the lepton forward-backward asymmetry $\mathscr{A}$FB as a function of the squared four-momentum of the dilepton system, q2, for the electroweak penguin process ...B→Xsℓ+ℓ- with a sum of exclusive final states, where ℓ is an electron or a muon and Xs is a hadronic recoil system with an s quark. The results are based on a data sample containing 772×106 $B$$\bar{B}$ pairs recorded at the Υ(4S) resonance with the Belle detector at the KEKB e+e- collider. $\mathscr{A}4FB for the inclusive B→Xsℓ+ℓ- is extrapolated from the sum of 10 exclusive Xs states whose invariant mass is less than 2 GeV/c2. For q2>10.2 GeV2/c2, $\mathscr{A}$FB<0 is excluded at the 2.3σ level, where σ is the standard deviation. For q2<4.3 GeV2/c2, the result is within 1.8σ of the Standard Model theoretical expectation.
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