Using 980.6 fb−1 of data collected with the Belle detector operating at the KEKB asymmetric-energy e+e− collider, we present a measurement of the branching fraction of the singly Cabibbo-suppressed ...decay ... . A clear ... signal is observed for ... with a statistical significance of 9.1 standard deviations, and we measure the ratio of branching fractions .../...=(1.32±0.12(stat)±0.10(syst))×10−2, from which we infer the branching fraction ... . The first quoted uncertainty is statistical, the second systematic, and the third from the reference mode ... . (ProQuest: … denotes formulae omitted.)
We report a search for X(3872) and X(3915) in B+→χc1π0K+ decays. We set an upper limit of B(B+→X(3872)K+)×B(X(3872)→χc1π0)<8.1×10−6 and B(B+→X(3915)K+)×B(X(3915)→χc1π0)<3.8×10−5 at 90% confidence ...level. We also measure B(X(3872)→χc1π0)/B(X(3872)→J/ψπ+π−)<0.97 at 90% confidence level. The results reported here are obtained from 772×106 BB events collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider.
We report the first evidence for X(3872) production in two-photon interactions by tagging either the electron or the positron in the final state, exploring the highly virtual photon region. The ...search is performed in e^{+}e^{-}→e^{+}e^{-}J/ψπ^{+}π^{-}, using 825 fb^{-1} of data collected by the Belle detector operated at the KEKB e^{+}e^{-} collider. We observe three X(3872) candidates, where the expected background is 0.11±0.10 events, with a significance of 3.2σ. We obtain an estimated value for Γover ˜_{γγ}B(X(3872)→J/ψπ^{+}π^{-}) assuming the Q^{2} dependence predicted by a ccover ¯ meson model, where -Q^{2} is the invariant mass squared of the virtual photon. No X(3915)→J/ψπ^{+}π^{-} candidates are found.
Abstract
Introduction
Ventricular arrhythmias (VA) represent a common complication of myocardial infarction (MI). Typically, they occur in two scenarios: during acute MI, related to ongoing ischemia, ...as ventricular tachycardia (VT) or ventricular fibrillation (VF), or in the context of a late phase of MI, related to the presence of a scar, as monomorphic VT (mVT). Despite the above, their occurrence may be atypical.
Clinical Case
55–year–old man affected by obesity, diabetes and hypertension, admitted to our department for subacute MI. Coronarography showed three–vessel disease with indication for surgical revascularization. Thirty hours after admission, in absence of symptoms, occurrence of cardiovascular arrest due to mVT, which degenerated into VF. After resuscitation, ECG and Echo findings did not change compared to those observed at admission, excluding the presence of current ischemia. A blood gas analysis excluded dysionias. Few minutes later, arrhythmic recurrence of mVT degenerated into VF. This was refractory to electrical and antiarrhythmic therapy and stopped only after percutaneous left stellate ganglion block (LSGB) and deep sedation. Then, emergency surgical revascularization was performed. In the early postoperative days, during weaning attempts from sedation and ECMO support, that had become necessary due to hemodynamic instability after surgery, numerous recurrences of mVT, regressed only after deepening of sedation, multiple external shocks, antiarrhythmic polytherapy, and LSGB. A new coronarography documented patency of coronary artery bypass grafts. On 6th postoperative day, discontinuation of deep sedation and weaning from circulatory support without recurrence of VA. The patient was discharged from the intensive care unit and started on a rehabilitation pathway.
Conclusions
mVTs are commonly related to the presence of a scar, formed late after MI, or to the context of ongoing ischemia in acute MI. However, it should be remembered that even during the subacute phase of MI, arrhythmic instability might still occur. The responsible mechanisms are not completely known but it can be assumed that, even in the absence of a new ischemic event, the process of scar maturation may have led to a transient proarrhythmic substrate, responsible for the arrhythmic storm. Further studies are needed to clarify the mechanisms of arrhythmogenesis in the subacute phase of MI.
A
bstract
Using a data sample of 980 fb
−
1
collected with the Belle detector at the KEKB asymmetric-energy
e
+
e
−
collider, we study for the first time the singly Cabibbo-suppressed decays
$$ ...{\Omega}_c^0\to {\Xi}^{-}{\pi}^{+} $$
Ω
c
0
→
Ξ
−
π
+
and Ω
−
K
+
and the doubly Cabibbo-suppressed decay
$$ {\Omega}_c^0\to {\Xi}^{-}{K}^{+} $$
Ω
c
0
→
Ξ
−
K
+
. Evidence for an
$$ {\Omega}_c^0 $$
Ω
c
0
signal in the
$$ {\Omega}_c^0 $$
Ω
c
0
→
Ξ
−
π
+
mode is reported with a significance of 4
.
5
σ
including systematic uncertainties. The ratio of branching fractions to the normalization mode
$$ {\Omega}_c^0 $$
Ω
c
0
→
Ω
−
π
+
is measured to be
$$ \mathcal{B}\left({\Omega}_c^0\to {\Xi}^{-}{\pi}^{+}\right)/\mathcal{B}\left({\Omega}_c^0\to {\Omega}^{-}{\pi}^{+}\right)=0.253\pm 0.052\left(\textrm{stat}.\right)\pm 0.030\left(\textrm{syst}.\right). $$
B
Ω
c
0
→
Ξ
−
π
+
/
B
Ω
c
0
→
Ω
−
π
+
=
0.253
±
0.052
stat
.
±
0.030
syst
.
.
No significant signals of
$$ {\Omega}_c^0\to {\Xi}^{-}{K}^{+} $$
Ω
c
0
→
Ξ
−
K
+
and Ω
−
K
+
modes are found. The upper limits at 90% confidence level on ratios of branching fractions are determined to be
$$ \mathcal{B}\left({\Omega}_c^0\to {\Xi}^{-}{K}^{+}\right)/\mathcal{B}\left({\Omega}_c^0\to {\Omega}^{-}{\pi}^{+}\right)<0.070 $$
B
Ω
c
0
→
Ξ
−
K
+
/
B
Ω
c
0
→
Ω
−
π
+
<
0.070
and
$$ \mathcal{B}\left({\Omega}_c^0\to {\Omega}^{-}{K}^{+}\right)/\mathcal{B}\left({\Omega}_c^0\to {\Omega}^{-}{\pi}^{+}\right)<0.29. $$
B
Ω
c
0
→
Ω
−
K
+
/
B
Ω
c
0
→
Ω
−
π
+
<
0.29
.
Operational experience of the Belle II pixel detector Wang, B.; Abudinen, F.; Ackermann, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2022, Letnik:
1032
Journal Article
Recenzirano
Odprti dostop
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.
We report a new measurement of the exclusive e+e−→D(*)±D*∓ cross sections as a function of the center-of-mass energy from the D(*)±D*∓ threshold through s=6.0 GeV, using the initial-state radiation ...technique. The analysis is based on a data sample collected with the Belle detector with an integrated luminosity of 951 fb−1. The accuracy of the cross section measurement is increased by a factor of 2 over the first Belle study. We perform the first angular analysis of the e+e−→D*±D*∓ process and decompose this exclusive cross section into three components corresponding to the D* helicities.
The DEPFET collaboration develops highly granular, ultra-transparent active pixel detectors for high-performance vertex reconstruction at future collider experiments. The characterization of detector ...prototypes has proven that the key principle, the integration of a first amplification stage in a detector-grade sensor material, can provide a comfortable signal to noise ratio of over 40 for a sensor thickness of 50-75 μm. ASICs have been designed and produced to operate a DEPFET pixel detector with the required read-out speed. A complete detector concept is being developed, including solutions for mechanical support, cooling, and services. In this paper, the status of the DEPFET R & D project is reviewed in the light of the requirements of the vertex detector at a future linear e + e - collider.
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