Abstract We study bottomonium production in association with an $$\eta $$ η meson in $$e^+e^-$$ e+e- annihilations near the $$\varUpsilon (5S)$$ Υ(5S) , at a centre-of-mass energy of ...$$\sqrt{s}=10.866$$ s=10.866 GeV. The results are based on the 121.4 fb$$^{-1}$$ -1 data sample collected by the Belle experiment at the asymmetric-energy KEKB collider. Only the $$\eta $$ η meson is reconstructed and the missing-mass spectrum of $$\eta $$ η candidates is investigated. We observe the $$e^+e^-\rightarrow \eta \varUpsilon _J(1D)$$ e+e-→ηΥJ(1D) process and find evidence for the $$e^+e^-\rightarrow \eta \varUpsilon (2S)$$ e+e-→ηΥ(2S) process, while no significant signals of $$\varUpsilon (1S)$$ Υ(1S) , $$h_b(1P)$$ hb(1P) , nor $$h_b(2P)$$ hb(2P) are found. Cross sections for the studied processes are reported.
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.
Abstract We report the first observation of the $$\Xi _{c}(2930)^0$$ Ξc(2930)0 charmed-strange baryon with a significance greater than 5$$\sigma $$ σ . The $$\Xi _{c}(2930)^0$$ Ξc(2930)0 is found in ...its decay to $$K^- \Lambda _{c}^+$$ K-Λc+ in $$B^{-} \rightarrow K^{-} \Lambda _{c}^{+} \bar{\Lambda }_{c}^{-}$$ B-→K-Λc+Λ¯c- decays. The measured mass and width are $$2928.9 \pm 3.0(\mathrm stat.)^{+0.9}_{-12.0}(\mathrm syst.)$$ 2928.9±3.0(stat.)-12.0+0.9(syst.) MeV/$$c^{2}$$ c2 and $$19.5 \pm 8.4(\mathrm stat.) ^{+5.9}_{-7.9}(\mathrm syst.)$$ 19.5±8.4(stat.)-7.9+5.9(syst.) MeV, respectively, and the product branching fraction is $$\mathcal{B}(B^{-} \rightarrow \Xi _{c}(2930)^0 \bar{\Lambda }_{c}^{-}) \mathcal{B}(\Xi _{c}(2930)^0 \rightarrow K^- \Lambda _{c}^{+})=1.73 \pm 0.45(\mathrm stat.) \pm 0.21(\mathrm syst.)\times 10^{-4}$$ B(B-→Ξc(2930)0Λ¯c-)B(Ξc(2930)0→K-Λc+)=1.73±0.45(stat.)±0.21(syst.)×10-4 . We also measure $$\mathcal{B}(B^{-} \rightarrow K^{-} \Lambda _{c}^{+} \bar{\Lambda }_{c}^{-}) = 4.80 \pm 0.43(\mathrm stat.) \pm 0.60(\mathrm syst.) \times 10^{-4}$$ B(B-→K-Λc+Λ¯c-)=4.80±0.43(stat.)±0.60(syst.)×10-4 with improved precision, and 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) nor its spin partner 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.
Study of γγ→γψ(2S) at Belle Wang, X. L.; Aihara, H.; Asner, D. M. ...
Physical review. D,
06/2022, Letnik:
105, Številka:
11
Journal Article
Recenzirano
Odprti dostop
Using 980 fb-1 of data at and around the Υ(nS)(n = 1, 2, 3, 4, 5) resonances collected with the Belle detector at the KEKB asymmetric-energy e+e- collider, the two-photon process γγ → γψ(2S) is ...studied from the threshold to 4.2 GeV for the first time. Two structures are seen in the invariant mass distribution of γψ(2S): one at MR1 = 3922.4 ± 6.5 ± 2.0 MeV/c2 with a width of ΓR1 = 22 ± 17 ± 4 MeV, and another at MR2 = 4014.3 ± 4.0 ± 1.5 MeV/c2 with a width of ΓR2 = 4 ± 11 ± 6 MeV; the signals are parametrized with the incoherent sum of two Breit- Wigner functions. The first structure is consistent with the X(3915) or the χc2(3930), and the local statistical significance is determined to be 3.1σ with the systematic uncertainties included. The second matches none of the known charmonium or charmonium like states, and its global significance is determined to be 2.8σ including the look-elsewhere effect. The production rates are Γγγ B(R1 → γψ(2S)) = 9.8 ± 3.6 ± 1.2 eV assuming (JPC, |λ|) = (0++, 0) or 2.0 ± 0.7 ± 0.2 eV with (2++, 2) for the first structure and Γγγ B(R2 → γψ(2S)) = 6.2 ± 2.2 ± 0.8 eV with (0++, 0) or 1.2 ± 0.4 ± 0.2 eV with (2++, 2) for the second one. Furthermore, the first errors are statistical and the second systematic, and λ is the helicity.
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.)
Abstract We measure the cross section of e + e − → η c J/ψ at the Υ(nS)(n = 1–5) on-resonance and 10.52 GeV off-resonance energy points using the full data sample collected by the Belle detector with ...an integrated luminosity of 955 fb −1. We also search for double charmonium production in e + e − → η c J/ψ via initial state radiation near the η c J/ψ threshold. No evident signal of the double charmonium state is found, but evidence for the e + e − → η c J/ψ process is found with a statistical significance greater than 3.3σ near the η c J/ψ threshold. The average cross section near the threshold is measured and upper limits of cross sections are set for other regions.
The cross section for e(+)e(-)-->pi(+)pi(-)J/psi between 3.8 and 5.5 GeV/c(2) is measured using a 548 fb(-1) data sample collected on or near the Upsilon(4S) resonance with the Belle detector at ...KEKB. A peak near 4.25 GeV/c(2), corresponding to the so called Y(4260), is observed. In addition, there is another cluster of events at around 4.05 GeV/c(2). A fit using two interfering Breit-Wigner shapes describes the data better than one that uses only the Y(4260), especially for the lower-mass side of the 4.25 GeV enhancement.
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