The measurement of two-particle angular correlation functions in high-multiplicity e+e− collisions at s=10.52 GeV is reported. In this study, the 89.5 fb−1 of hadronic e+e− annihilation data collected by the Belle d...
详细信息
The measurement of two-particle angular correlation functions in high-multiplicity e+e− collisions at s=10.52 GeV is reported. In this study, the 89.5 fb−1 of hadronic e+e− annihilation data collected by the Belle detector at KEKB are used. Two-particle angular correlation functions are measured in the full relative azimuthal angle (Δϕ) and three units of pseudorapidity (Δη), defined by either the electron beam axis or the event-shape thrust axis, and are studied as a function of charged-particle multiplicity. The measurement in the thrust axis analysis, with mostly outgoing quark pairs determining the reference axis, is sensitive to the region of additional soft gluon emissions. No significant anisotropic collective behavior is observed with either coordinate analyses. Near-side jet correlations appear to be absent in the thrust axis analysis. The measurements are compared to predictions from various event generators and are expected to provide new constraints to the phenomenological models in the low-energy regime.
We present the first observation of the Ωc0→Ω−μ+νμ decay and present measurements of the branching fraction ratios of the Ωc0→Ω−ℓ+νℓ decays compared to the reference mode Ωc0→Ω−π+, (ℓ=e or μ). This anal...
详细信息
We present the first observation of the Ωc0→Ω−μ+νμ decay and present measurements of the branching fraction ratios of the Ωc0→Ω−ℓ+νℓ decays compared to the reference mode Ωc0→Ω−π+, (ℓ=e or μ). This analysis is based on 89.5 fb−1, 711 fb−1, and 121.1 fb−1 data samples collected with the Belle detector at the KEKB asymmetric-energy e+e− collider at the center-of-mass energies of 10.52 GeV, 10.58 GeV, and 10.86 GeV, respectively. The Ωc0 signal yields are extracted by fitting MΩℓ and MΩπ spectra. The branching fraction ratios B(Ωc0→Ω−e+νe)/B(Ωc0→Ω−π+) and B(Ωc0→Ω−μ+νμ)/B(Ωc0→Ω−π+) are measured to be 1.98±0.13(stat)±0.08(syst) and 1.94±0.18(stat)±0.10(syst), respectively. The ratio of B(Ωc0→Ω−e+νe)/B(Ωc0→Ω−μ+νμ) is measured to be 1.02±0.10(stat)±0.02(syst), which is consistent with the expectation of lepton flavor universality.
We search for a new gauge boson Z′ that couples only to heavy leptons and their corresponding neutrinos in the process e+e−→Z′(→μ+μ−)μ+μ−, using a 643 fb−1 data sample collected by the Belle experiment at or ...
详细信息
We search for a new gauge boson Z′ that couples only to heavy leptons and their corresponding neutrinos in the process e+e−→Z′(→μ+μ−)μ+μ−, using a 643 fb−1 data sample collected by the Belle experiment at or near the ϒ(1S,2S,3S,4S,5S) resonances at the KEKB collider. While previous searches for Z′ performed a data-based estimation of the initial state radiation effect, our search for the Z′ is the first to include effects due to initial state radiation in the signal simulated samples that were used in estimating the detection efficiency. No signal is observed in the Z′ mass range of 0.212–10 GeV/c2, and we set an upper limit on the coupling strength, g′, constraining the possible Z′ contribution to the anomalous magnetic dipole moment of the muon.
We measure the branching fractions and CP asymmetries for the decays B0→D¯0π0 and B+→D¯0π+, using a data sample of 772×106 BB¯ pairs collected at the ϒ(4S) resonance with the Belle detector at...
详细信息
We measure the branching fractions and CP asymmetries for the decays B0→D¯0π0 and B+→D¯0π+, using a data sample of 772×106 BB¯ pairs collected at the ϒ(4S) resonance with the Belle detector at the KEKB e+e− collider. The branching fractions obtained and direct CP asymmetries are B(B0→D¯0π0)=[2.70±0.06(stat)±0.10(syst)]×10−4, B(B+→D¯0π+)=[4.53±0.02(stat)±0.15(syst)]×10−3, ACP(B0→D¯0π0)=[+0.42±2.05(stat)±1.22(syst)]%, and ACP(B+→D¯0π+)=[+0.19±0.36(stat)±0.57(syst)]%. The measurements of B are the most precise to date and are in good agreement with previous results, as is the measurement of ACP(B+→D¯0π+). The measurement of ACP for B0→D¯0π0 is the first for this mode, and the value is consistent with Standard Model expectations.
We report results from the first search for the rare penguin-dominated decay mode B0→KS0KS0γ, which can result from the production of tensor mesons f(1270) and f′(1525) in association with a photon. The search uses...
详细信息
We report results from the first search for the rare penguin-dominated decay mode B0→KS0KS0γ, which can result from the production of tensor mesons f(1270) and f′(1525) in association with a photon. The search uses the full data sample of 772×106 BB¯ pairs collected with the Belle detector at the KEKB asymmetric-energy e+e− collider. No statistically significant signals are observed in the KS0KS0 invariant mass range 1 GeV/c2
We report the first direct measurement of the inclusive branching fraction B(Bs→DsX) via Bs tagging in e+e−→ϒ(5S) events. Tagging is accomplished through a partial reconstruction of semileptonic decays Bs→DsXℓν, w...
详细信息
We report the first direct measurement of the inclusive branching fraction B(Bs→DsX) via Bs tagging in e+e−→ϒ(5S) events. Tagging is accomplished through a partial reconstruction of semileptonic decays Bs→DsXℓν, where X denotes unreconstructed additional hadrons or photons and ℓ is an electron or muon. With 121.4 fb−1 of data collected at the ϒ(5S) resonance by the Belle detector at the KEKB asymmetric-energy e+e− collider, we obtain B(Bs→DsX)=(60.2±5.8±2.3)%, where the first uncertainty is statistical and the second is systematic.
Using the entire data sample of 980 fb−1 collected with the Belle detector at the KEKB asymmetric-energy e+e− collider, we present measurements of the branching fractions of the Cabibbo-favored decays Ξc0→ΛKS0, ...
详细信息
Using the entire data sample of 980 fb−1 collected with the Belle detector at the KEKB asymmetric-energy e+e− collider, we present measurements of the branching fractions of the Cabibbo-favored decays Ξc0→ΛKS0, Ξc0→Σ0KS0, and Ξc0→Σ+K−. Taking the decay Ξc0→Ξ−π+ as the normalization mode, we measure the branching fraction ratio B(Ξc0→ΛKS0)/B(Ξc0→Ξ−π+)=0.229±0.008±0.012 with improved precision, and measure the branching fraction ratios B(Ξc0→Σ0KS0)/B(Ξc0→Ξ−π+)=0.038±0.006±0.004 and B(Ξc0→Σ+K−)/B(Ξc0→Ξ−π+)=0.123±0.007±0.010 for the first time. Taking into account the branching fraction of the normalization mode, the absolute branching fractions are determined to be B(Ξc0→ΛKS0)=(3.27±0.11±0.17±0.73)×10−3, B(Ξc0→Σ0KS0)=(0.54±0.09±0.06±0.12)×10−3, and B(Ξc0→Σ+K−)=(1.76±0.10±0.14±0.39)×10−3. The first and second uncertainties above are statistical and systematic, respectively, while the third ones arise from the uncertainty of the branching fraction of Ξc0→Ξ−π+.
A search for double-heavy tetraquark state candidates Xccs¯s¯ decaying to Ds+Ds+ and Ds*+Ds*+ is presented for the first time using the data samples of 102×106 ϒ(1S) and 158×106 ϒ(2S) events, and t...
详细信息
A search for double-heavy tetraquark state candidates Xccs¯s¯ decaying to Ds+Ds+ and Ds*+Ds*+ is presented for the first time using the data samples of 102×106 ϒ(1S) and 158×106 ϒ(2S) events, and the data samples at s=10.52, 10.58, and 10.867 GeV corresponding to integrated luminosities of 89.5, 711.0, and 121.4 fb−1, respectively, accumulated with the Belle detector at the KEKB asymmetric energy electron-positron collider. The invariant-mass spectra of the Ds+Ds+ and Ds*+Ds*+ are studied to search for possible resonances. No significant signals are observed, and the 90% confidence level upper limits on the product branching fractions [B(ϒ(1S,2S)→Xccs¯s¯+anything)×B(Xccs¯s¯→Ds+Ds+(Ds*+Ds*+))] in ϒ(1S,2S) inclusive decays and the product values of Born cross section and branching fraction [σ(e+e−→Xccs¯s¯+anything)×B(Xccs¯s¯→Ds+Ds+(Ds*+Ds*+))] in e+e− collisions at s=10.52, 10.58, and 10.867 GeV under different assumptions of Xccs¯s¯ masses and widths are obtained.
We report the results of the first search for the decay Bs0→η′KS0 using 121.4 fb−1 of data collected at the ϒ(5S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. We observe no signal...
详细信息
We report the results of the first search for the decay Bs0→η′KS0 using 121.4 fb−1 of data collected at the ϒ(5S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. We observe no signal and set a 90% confidence-level upper limit of 8.16×10−6 on the Bs0→η′KS0 branching fraction.
We report results from a search for the decay Bs0→ηη using 121.4 fb−1 of data collected at the ϒ(5S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. We do not observe any signal and ...
详细信息
We report results from a search for the decay Bs0→ηη using 121.4 fb−1 of data collected at the ϒ(5S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. We do not observe any signal and set an upper limit on the branching fraction of 14.3×10−5 at 90% confidence level. This result represents a significant improvement over the previous most stringent limit.
暂无评论