A
bstract
We present measurements of the branching fractions for the decays
B
→
Kμ
+
μ
−
and
B
→
Ke
+
e
−
, and their ratio (
R
K
), using a data sample of 711 fb
−
1
that contains 772 × 10
6
B
B
¯
...events. The data were collected at the ϒ(4
S
) resonance with the Belle detector at the KEKB asymmetric-energy
e
+
e
−
collider. The ratio
R
K
is measured in five bins of dilepton invariant-mass-squared (
q
2
):
q
2
∈ (0
.
1
,
4
.
0)
,
(4
.
00
,
8
.
12)
,
(1
.
0
,
6
.
0), (10
.
2
,
12
.
8) and (
>
14
.
18) GeV
2
/c
4
, along with the whole
q
2
region. The
R
K
value for
q
2
∈ (1
.
0
,
6
.
0) GeV
2
/c
4
is
1.03
−
0.24
+
0.28
± 0
.
01. The first and second uncertainties listed are statistical and systematic, respectively. All results for
R
K
are consistent with Standard Model predictions. We also measure
CP
-averaged isospin asymmetries in the same
q
2
bins. The results are consistent with a null asymmetry, with the largest difference of 2.6 standard deviations occurring for the
q
2
∈ (1
.
0
,
6
.
0) GeV
2
/c
4
bin in the mode with muon final states. The measured differential branching fractions,
d
ℬ
/dq
2
, are consistent with theoretical predictions for charged
B
decays, while the corresponding values are below the expectations for neutral
B
decays. We have also searched for lepton-flavor-violating
B
→
Kμ
±
e
∓
decays and set 90% confidence-level upper limits on the branching fraction in the range of 10
−
8
for
B
+
→
K
+
μ
±
e
∓
, and
B
0
→
K
0
μ
±
e
∓
modes.
A
bstract
Charged lepton flavor violation is forbidden in the Standard Model but possible in several new physics scenarios. In many of these models, the radiative decays
τ
±
→
ℓ
±
γ
(
ℓ
=
e, μ
) are ...predicted to have a sizeable probability, making them particularly interesting channels to search at various experiments. An updated search via
τ
±
→
ℓ
±
γ
using full data of the Belle experiment, corresponding to an integrated luminosity of 988 fb
−
1
, is reported for charged lepton flavor violation. No significant excess over background predictions from the Standard Model is observed, and the upper limits on the branching fractions,
B
(
τ
±
→
μ
±
γ
) ≤ 4
.
2 × 10
−
8
and
B
(
τ
±
→
e
±
γ
) ≤ 5
.
6 × 10
−
8
, are set at 90% confidence level.
This paper investigates the perception of security risk and causes of crimes in gated and non-gated communities in Lahore, Pakistan. Due to increasing rate of crimes in the city, the trend and demand ...of gated communities are rising. People living in non-gated communities have installed barriers and gates in through streets to prevent crimes. The data was collected by conducting face to face interviews with the residents of a gated and non-gated community in Lahore, concerned officials of police stations and Lahore Development Authority using structured questionnaires. Results of data analysis revealed that the residents with high-income experience fewer crimes than the residents with low/middle income, since they are more vulnerable to crimes. The perception of insecurity among the residents is directly proportional to the frequency of crimes in that community. Moreover, residents of gated community are more satisfied with the safety and security measures. Several through streets in each block of non-gated community are facilitating crimes. This shows that the layout plan of residential community also plays an important role in facilitating/reducing the crime. The number of reported crimes in the non-gated community is 25 times higher than the reported crimes in the gated community. Un-registered tenants are also found to be indulged in criminal activities in such communities. Recommendations are made to transform both types of communities and plan future neighbourhoods as more safer places for living.
A
bstract
We present a search for the charged lepton-flavor-violating decays ϒ(1
S
)
→
ℓ
±
ℓ
′
∓
and radiative charged lepton-flavour-violating decays ϒ(1
S
)
→ γ
ℓ
±
ℓ
′
∓
ℓ
,
ℓ
′ =
e, μ, τ
using ...the 158 million ϒ(2
S
) sample collected by the Belle detector at the KEKB collider. This search uses ϒ(1
S
) mesons produced in ϒ(2
S
)
→ π
+
π
−
ϒ(1
S
) transitions. We do not find any significant signal, so we provide upper limits on the branching fractions at the 90% confidence level.
Addition chloro acetyl isothiocyanate (C3H2ClNOS) with 3-Aminoaceto phenone (C8H9NO) to prepare a fresh Ligand N-(3-acetyl phenyl carbamothioyl)-2-chloroacetamide(L). The ligand (L) behaves as ...bidentate coordinating through O and S donor with metal ions, the general formula of all complexes M(L)2(Cl)2(M+2 = Manganese(II), Cobalt(II), Cadmium(II) and Mercury(II)). Compounds were investigation by Proton-1, Carbon -13 NMR spectra (ligand (L) only), Element Microanalysis for C, N, H, O, S, Fourier-transform infrared, UV visible, Conductance, Magnetic susceptibility and Atomic Absorption (A.A). Based on spectral data, complexes appear octahedral geometry. The anti-bacterial activity of the complexes against two type of bacterial was higher than for free ligand.
A
bstract
We present the analysis of two-particle angular correlations using coordinate systems defined with the conventional beam axis and the event thrust axis. We propose the latter as a good ...representation for the correlation structure interpretation in the
e
+
e
−
collision system. The
e
+
e
−
collisions to hadronic final states at center-of-mass energies of
s
= 10
.
52 GeV and 10.58 GeV are recorded by the Belle detector at KEKB. In this paper, results on the first dataset are supplementary to the previous Belle publication
1
. At the same time, the latter is the first two-particle correlation measurement at collision energy on the
Υ
(4
S
) resonance and is sensitive to its decay products. Measurements are reported as a function of the charged-particle multiplicity. Finally, a qualitative understanding of the correlation structure is discussed using a combination of Monte Carlo simulations and experimental data.
A
bstract
We report the measurement of the two-photon decay width of
χ
c
2
(1
P
) in two-photon processes at the Belle experiment. We analyze the process
γγ
→
χ
c
2
(1
P
) →
J/ψγ
,
J/ψ
→
ℓ
+
ℓ
−
(
ℓ
...=
e
or
μ
) using a data sample of 971 fb
−
1
collected with the Belle detector at the KEKB
e
+
e
−
collider. In this analysis, the product of the two-photon decay width of
χ
c
2
(1
P
) and the branching fraction is determined to be
Γ
γγ
χ
c
2
1
P
B
χ
c
2
1
P
→
J
/
ψγ
B
J
/
ψ
→
ℓ
+
ℓ
−
=
14.8
±
0.3
stat
.
±
0.7
syst
.
eV, which corresponds to Γ
γγ
(
χ
c
2
(1
P
)) = 653
±
13(stat.)
±
31(syst.)
±
17(B.R.) eV, where the third uncertainty is from
B
(
χ
c
2
(1
P
)
→ J/ψγ
) and
B
(
J/ψ → ℓ
+
ℓ
−
).
Slow control of the Belle II Aerogel Ring Imaging detector Pestotnik, R.; Adachi, I.; Adamczyk, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2023, Letnik:
1056
Journal Article
Recenzirano
Odprti dostop
Since 2018, an Proximity Focusing Aerogel Ring Imaging Detector (ARICH) efficiently separates hadrons in the forward end-cap of the Belle II spectrometer. Cherenkov photons emitted in the ...double-layer aerogel radiator are expanded in 16-cm space and detected on the photon detector, which consists of 420 hybrid avalanche photodiodes and rear readout electronics operating in threshold mode. Each of the sensors requires six different high voltages and a supply of four low voltages for the electronics. Because of the power dissipation, the system also includes a cooling system in which cold water circulates through the Al tubes thermally connected to the readout electronics. Reliable control of supply voltages and monitoring of environmental data and sensor status ensure stable operation of the ARICH detector and early response to sudden changes in current, single event disturbances, overheating, and other faults. In this paper, we introduce the ARICH’s slow control system and the data quality monitor used to track performance.
This study analyzes the growth of a vapour bubble in a superheated nanofluid with variable surface tension at the bubble interface. The governing equations describing the problem are formulated, ...converted to a single integrodifferential equation, and solved analytically. The results are implemented in one of the favorable nanofluids, namely, Al2O3/water, since it is widely used in nanofluid applications, which include self-cooling devices and as a coolant in newly designed photovoltaic/thermal systems, because it has higher thermal and electrical physical properties than the base fluid and a lower economical preparation cost. The results showed that the growth process is proportional to the thermal diffusivity and the Jakob number, while it is inversely proportional to surface tension, dynamic viscosity, initial bubble radius, coefficient of the initial pressure difference, initial void fraction, and nanoparticle volume fraction. Moreover, we conducted a comparison to the experimental data obtained by Hamda and Hamed (2016), and our results achieved a better agreement with these data than some famous studies for both experiments for superheated Al2O3/water nanofluid and pure water (base fluid), because our model considered the effects of several parameters that were ignored in the previous theories, which have been derived as special cases of our result. Furthermore, the effects of nanoparticle characteristics and slip mechanisms; base fluid type and temperature; and the addition of surfactants on bubble growth rates are investigated. Implications drawn from this study may have consequences for the optimum design of thermal systems/devices based on nanofluid technology.
•Growth of a vapour bubble in a viscous, superheated nanofluid is analytically investigated.•This model considers the effect of several parameters that were omitted in the previous theories.•Obtained results are better than previous studies to agree with modern experiment for superheated Al2O3/Water nanofluid.•Effects of surrounding parameters; nanoparticle characteristics and slip mechanisms on the bubble growth are discussed.
In the forward end-cap of the Belle II spectrometer, particle identification is provided by a proximity focusing RICH detector with an aerogel radiator (ARICH). The ARICH’s primary function is to ...effectively distinguish between pions and kaons in the momentum range of 0.5GeV/c to about 4GeV/c, as well as to contribute to identification of low-momentum leptons. Since its operation began, Belle II has collected over 420fb−1 of data. Based on this large data sample, studies of several effects that impact the performance of the ARICH detector were carried out. In this paper, we present a comparison of the observed Cherenkov ring image and detector particle identification performance in the measured data and detector simulation. Furthermore, we highlight recent efforts aimed at enhancing the ARICH’s performance by taking into account the effects of particle decay in flight and scattering in materials before the detector, as well as by refining the probability density function used for particle identification likelihood evaluation.