We report the results of a search for the rare, purely leptonic decay B−→μ−ν¯μ performed with a 711 fb−1 data sample that contains 772×106 BB¯ pairs, collected near the ϒ(4S) resonance with the ...Belle detector at the KEKB asymmetric-energy e+e− collider. The signal events are selected based on the presence of a high momentum muon and the topology of the rest of the event showing properties of a generic B-meson decay, as well as the missing energy and momentum being consistent with the hypothesis of a neutrino from the signal decay. We find a 2.4 standard deviation excess above background including systematic uncertainties, which corresponds to a branching fraction of B(B−→μ−ν¯μ)=(6.46±2.22±1.60)×10−7 or a frequentist 90% confidence level interval on the B−→μ−ν¯μ branching fraction of 2.9,10.7×10−7.
We report evidence for the charged charmed-strange baryon \(\Xi _{c}(2930)^+\) with a signal significance of 3.9 \(\sigma \) with systematic errors included. The charged \(\Xi _{c}(2930)^+\) is found ...in its decay to \(K_{S}^{0} \Lambda _{c}^+\) in the substructure of \(\bar{B}^{0} \rightarrow K^{0}_{S} \Lambda _{c}^{+} \bar{\Lambda }_{c}^{-}\) decays. The measured mass and width are \(2942.3 \pm 4.4 ({\mathrm{stat.}}) \pm {1.5}({\mathrm{syst.}})\) MeV/ \(c^{2}\) and \(14.8 \pm 8.8({\mathrm{stat.}}) \pm {2.5}({\mathrm{syst.}})\) MeV, respectively, and the product branching fraction is \(\mathcal{B}(\bar{B}^{0} \rightarrow \Xi _c(2930)^{+} \bar{\Lambda }_{c}^{-}) \mathcal{B}(\Xi _c(2930)^{+}\rightarrow \bar{K}^{0} \Lambda _{c}^{+})=2.37 \pm 0.51 ({\mathrm{stat.}})\pm 0.31({\mathrm{syst.}})\times 10^{-4}\) . We also measure \(\mathcal{B}(\bar{B}^{0} \rightarrow \bar{K}^{0} \Lambda _{c}^{+} \bar{\Lambda }_{c}^{-}) = 3.99 \pm 0.76({\mathrm{stat.}}) \pm 0.51({\mathrm{syst.}}) \times 10^{-4}\) with greater precision than previous experiments, and present the results of a search for the charmonium-like state Y(4660) and its spin partner, \(Y_{\eta }\) , in the \(\Lambda _{c}^{+}\bar{\Lambda }_{c}^{-}\) invariant mass spectrum. No clear signals of the Y(4660) or \(Y_{\eta }\) are observed and the 90% credibility level (C.L.) upper limits on their production rates are determined. These measurements are obtained from a sample of \((772\pm 11)\times 10^{6} B\bar{B}\) pairs collected at the \(\Upsilon (4S)\) resonance by the Belle detector at the KEKB asymmetric energy electron-positron collider.
Abstract We report evidence for the charged charmed-strange baryon $$\Xi _{c}(2930)^+$$ Ξc(2930)+ with a signal significance of 3.9$$\sigma $$ σ with systematic errors included. The charged $$\Xi ..._{c}(2930)^+$$ Ξc(2930)+ is found in its decay to $$K_{S}^{0} \Lambda _{c}^+$$ KS0Λc+ in the substructure of $$\bar{B}^{0} \rightarrow K^{0}_{S} \Lambda _{c}^{+} \bar{\Lambda }_{c}^{-}$$ B¯0→KS0Λc+Λ¯c- decays. The measured mass and width are $$2942.3 \pm 4.4 ({\mathrm{stat.}}) \pm {1.5}({\mathrm{syst.}})$$ 2942.3±4.4(stat.)±1.5(syst.) MeV/$$c^{2}$$ c2 and $$14.8 \pm 8.8({\mathrm{stat.}}) \pm {2.5}({\mathrm{syst.}})$$ 14.8±8.8(stat.)±2.5(syst.) MeV, respectively, and the product branching fraction is $$\mathcal{B}(\bar{B}^{0} \rightarrow \Xi _c(2930)^{+} \bar{\Lambda }_{c}^{-}) \mathcal{B}(\Xi _c(2930)^{+}\rightarrow \bar{K}^{0} \Lambda _{c}^{+})=2.37 \pm 0.51 ({\mathrm{stat.}})\pm 0.31({\mathrm{syst.}})\times 10^{-4}$$ B(B¯0→Ξc(2930)+Λ¯c-)B(Ξc(2930)+→K¯0Λc+)=2.37±0.51(stat.)±0.31(syst.)×10-4 . We also measure $$\mathcal{B}(\bar{B}^{0} \rightarrow \bar{K}^{0} \Lambda _{c}^{+} \bar{\Lambda }_{c}^{-}) = 3.99 \pm 0.76({\mathrm{stat.}}) \pm 0.51({\mathrm{syst.}}) \times 10^{-4}$$ B(B¯0→K¯0Λc+Λ¯c-)=3.99±0.76(stat.)±0.51(syst.)×10-4 with greater precision than previous experiments, and present the results of a search for the charmonium-like state Y(4660) and its spin partner, $$Y_{\eta }$$ Yη , in the $$\Lambda _{c}^{+}\bar{\Lambda }_{c}^{-}$$ Λc+Λ¯c- invariant mass spectrum. No clear signals of the Y(4660) or $$Y_{\eta }$$ Yη are observed and the 90% credibility level (C.L.) upper limits on their production rates are determined. These measurements are obtained from a sample of $$(772\pm 11)\times 10^{6} B\bar{B}$$ (772±11)×106BB¯ pairs collected at the $$\Upsilon (4S)$$ Υ(4S) resonance by the Belle detector at the KEKB asymmetric energy electron-positron collider.
Abstract We present a search for the lepton-flavor-violating decays B s 0 $$ {B}_s^0 $$ → ℓ ∓ τ ± , where ℓ = e, μ, using the full data sample of 121 fb −1 collected at the Υ(5S) resonance with the ...Belle detector at the KEKB asymmetric-energy e + e − collider. We use B s 0 B ¯ s 0 $$ {B}_s^0{\overline{B}}_s^0 $$ events in which one B s 0 $$ {B}_s^0 $$ meson is reconstructed in a semileptonic decay mode and the other in the signal mode. We find no evidence for B s 0 $$ {B}_s^0 $$ → ℓ ∓ τ ± decays and set upper limits on their branching fractions at 90% confidence level as B $$ \mathcal{B} $$ ( B s 0 $$ {B}_s^0 $$ → e ∓ τ ± ) < 14 × 10 −4 and B $$ \mathcal{B} $$ ( B s 0 $$ {B}_s^0 $$ → μ ∓ τ ± ) < 7.3 × 10 −4. Our result represents the first upper limit on the B s 0 $$ {B}_s^0 $$ → e ∓ τ ± decay rate.
We report evidence for the charged charmed-strange baryon
Ξ
c
(
2930
)
+
with a signal significance of 3.9
σ
with systematic errors included. The charged
Ξ
c
(
2930
)
+
is found in its decay to
K
S
0
...Λ
c
+
in the substructure of
B
¯
0
→
K
S
0
Λ
c
+
Λ
¯
c
-
decays. The measured mass and width are
2942.3
±
4.4
(
stat
.
)
±
1.5
(
syst
.
)
MeV/
c
2
and
14.8
±
8.8
(
stat
.
)
±
2.5
(
syst
.
)
MeV, respectively, and the product branching fraction is
B
(
B
¯
0
→
Ξ
c
(
2930
)
+
Λ
¯
c
-
)
B
(
Ξ
c
(
2930
)
+
→
K
¯
0
Λ
c
+
)
=
2.37
±
0.51
(
stat
.
)
±
0.31
(
syst
.
)
×
10
-
4
. We also measure
B
(
B
¯
0
→
K
¯
0
Λ
c
+
Λ
¯
c
-
)
=
3.99
±
0.76
(
stat
.
)
±
0.51
(
syst
.
)
×
10
-
4
with greater precision than previous experiments, and present the results of a search for the charmonium-like state
Y
(4660) and its spin partner,
Y
η
, in the
Λ
c
+
Λ
¯
c
-
invariant mass spectrum. No clear signals of the
Y
(4660) or
Y
η
are observed and the 90% credibility level (C.L.) upper limits on their production rates are determined. These measurements are obtained from a sample of
(
772
±
11
)
×
10
6
B
B
¯
pairs collected at the
Υ
(
4
S
)
resonance by the Belle detector at the KEKB asymmetric energy electron-positron collider.
We present a measurement of the muon neutrino–nucleon inclusive charged current cross section, off an isoscalar target, in the neutrino energy range 2.5⩽Eν⩽40 GeV. The significance of this ...measurement is its precision, ±4% in 2.5⩽Eν⩽10 GeV, and ±2.6% in 10⩽Eν⩽40 GeV regions, where significant uncertainties in previous experiments still exist, and its importance to the current and proposed long baseline neutrino oscillation experiments.
PDF
