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 novel load-controlled iteration scheme is proposed within the XFEM framework for semipermeable piezoelectric material.•Interaction integral approach is used to evaluate the electric displacement ...intensity factor (EDIF).•Effect of polarization angle, crack length, loading parameter is investigated on the electric displacement intensity factor.•EDIF results show an excellent agreement with the results obtained from the iterative capacitor analogy (ICA).
In the present work, a novel load-controlled iteration scheme within the framework of extended finite element method (XFEM) is proposed to model the semipermeable crack in a piezoelectric material. To capture the stress and electric displacement singularity at the crack tip, the electromechanical 6-fold enrichment functions are used. The domain form of electromechanical interaction integral is employed to determine the generalized intensity factor. The accuracy of a proposed scheme based on XFEM is validated against the reference solutions derived from the iterative capacitor analogy (ICA) method. The effect of several crack configurations, polarization angle, far-field mechanical and electrical traction on electric displacement intensity factor (EDIF) are analyzed for cracked semipermeable piezoelectric material.
•A crack opening model based on XFEM has been proposed to study the role of electrostatic tractions in cracked semipermeable piezoelectric material.•The electromechanical interaction integral ...approach is adopted to evaluate EDIF.•The EDIF obtained using the proposed model is found in excellent agreement with the analytical solution.•The effect of crack length, polarization angle, far-field loading, and electrostatic tractions is studied on EDIF.
In this work, a crack opening model is proposed to study the role of electrostatic tractions in a cracked semipermeable piezoelectric material. The extended finite element method (XFEM) is used in conjunction with six-fold electro-mechanical enrichment functions to capture the singularity and the discontinuous surface independent of the background mesh. The electric displacement intensity factor (EDIF) is evaluated using an electromechanical interaction integral approach in the presence of a dielectric medium inside the crack cavity. The accuracy of the proposed XFEM based approach is verified by comparing the numerical results with available analytical solutions. Further, a systematic numerical study is done to study the influence of electrostatic tractions on the EDIF using different crack configurations under far-field loading.
Earthquakes. Himalayan seismic hazard Bilham, R; Gaur, V K; Molnar, P
Science (American Association for the Advancement of Science),
2001-Aug-24, 20010824, Letnik:
293, Številka:
5534
Journal Article
GPS data reveal that the Brahmaputra Valley has broken from the Indian Plate and rotates clockwise relative to India about a point a few hundred kilometers west of the Shillong Plateau. The GPS ...velocity vectors define two distinct blocks separated by the Kopili fault upon which 2–3 mm/yr of dextral slip is observed: the Shillong block between longitudes 89 and 93°E rotating clockwise at 1.15°/Myr and the Assam block from 93.5°E to 97°E rotating at ≈1.13°/Myr. These two blocks are more than 120 km wide in a north‐south sense, but they extend locally a similar distance beneath the Himalaya and Tibet. A result of these rotations is that convergence across the Himalaya east of Sikkim decreases in velocity eastward from 18 to ≈12 mm/yr and convergence between the Shillong Plateau and Bangladesh across the Dauki fault increases from 3 mm/yr in the west to >8 mm/yr in the east. This fast convergence rate is inconsistent with inferred geological uplift rates on the plateau (if a 45°N dip is assumed for the Dauki fault) unless clockwise rotation of the Shillong block has increased substantially in the past 4–8 Myr. Such acceleration is consistent with the reported recent slowing in the convergence rate across the Bhutan Himalaya. The current slip potential near Bhutan, based on present‐day convergence rates and assuming no great earthquake since 1713 A.D., is now ~5.4 m, similar to the slip reported from alluvial terraces that offsets across the Main Himalayan Thrust and sufficient to sustain a Mw ≥ 8.0 earthquake in this area.
Key Points
New GPS velocity field in eastern HimalayaShillong Plateau is independent from IndiaStrain accumulated since the last earthquake is sufficient for a M > 8 earthquake
We use broad-band teleseismic data recorded at eight sites along a north—south profile from Karimganj (24.84°N, 92.34°E), south of the eastern Shillong Plateau, to Bomdilla (27.27°N, 92.41°E) in the ...eastern Lesser Himalaya, to determine the seismic characteristics of the crust in northeastern India. We also analyse data from the Chinese Digital Seismic Network station at Lhasa and INDEPTHII stations located on the southern Tibetan Plateau north of our profile, to extend the seismic images of the crust further northwards. Although the northeastern Indian stations and the Tibetan the well-recognized uniformity of the Himalaya along strike make this comparison of the two profiles meaningful. Receiver functions calculated from these data show that the crust is thinnest (∼35–38 km) beneath the Shillong Plateau. Receiver functions at Cherrapunji, on the southern edge of the Shillong Plateau, have a strong azimuthal dependence. Those from northern backazimuth events show that the Moho beneath the southernmost Shillong Plateau is at a depth of ∼38 km while receiver functions from southern backazimuth events indicate that the Moho beneath the northernmost Bengal Basin is at a depth of ∼44 km. Receiver functions from sites on the Brahmaputra Valley demonstrate that the Moho is deeper by ∼5–7 km than below the Shillong Plateau, a result which agrees with the hypothesis that the Shillong Plateau is supported by shearing stress on two steep faults that cut through the crust. Further north of the eastern Himalayan foredeep, the Moho dips gently northwards, reaching a depth of ∼48 km beneath Bomdilla in the Lesser Himalaya, and 88 km below Lhasa in Tibet. Using the crustal velocity models obtained from receiver function inversions, we redetermined focal depths of well-recorded earthquakes across this part of the Indo-Tibetan collision zone and find all of these to occur within the crust. Hence we find no evidence for bimodal depth distribution of earthquakes beneath this region of northeastern India.
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.
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