We review the recent results from the Belle experiment on the measurements of branching fractions and decay asymmetry parameters (α) for the hadronic weak decays of charmed baryons, including ...Λc+→B+P: Λc+→(Λ,Σ0)h+ (h=π,K) and Λc+→Σ+(π0,η,η′); Ξc0→B+P: Ξc0→Ξ−π+; Ξc0→B+V: Ξc0→ΛK¯*0, Ξc0→Σ0K¯*0, and Ξc0→Σ+K*−. In addition, we present an overview of the searches for CP violation via the α-induced CP asymmetry for Λc+→(Λ,Σ0)h+ and Ξc0→Ξ−π+. Finally, we discuss the promising decay modes of Ωc0 which can be measured in the near future and are indispensable in searching for CP violation in the charm sector.
Quarkonium (-like) states at BELLE Krokovny, Pavel
Nuclear and particle physics proceedings,
April-June 2016, 2016-04-00, Letnik:
273-275
Journal Article
Recenzirano
Odprti dostop
We report the recent results on quarkonium (-like) states by the Belle experiment. A new charged charmonium-like state Zc(4200)+ decaying to J/ψπ+ is observed with a significance of 6.2σ. The mass ...and width of the Zc(4200)+ are 4196−29−13+31+17 MeV/c2 and 370−70−132+70+70 MeV, respectively; the preferred assignment of the quantum numbers is JP=1+. We also report the first observation of the e+e−→ωπ+π−π0χbJ(J=1,2) processes at a center-of-mass energy of 10.867 GeV. In the π+π−π0 invariant mass spectrum, significant non-ω signals are also observed.
The primary purpose in the Belle experiment at the asymmetric-energy e/sup =/e/sup -/ collider at the High-Energy Accelerator Research Organization (KEK B factory) is the measurement of charge ...conjugation and parity (CP) violation in B meson decays. The K/sub L/ mesons and muons (KLM) detector was designed to identify K/sub L/'s and muons in this experiment. Since October 2001, the luminosity in the KEK B accelerator has been remarkably improved. The data on B meson decay are successfully collected in the Belle detector. In contrast with the high luminosity operations of the accelerator, however, the high background rate leading to a lower detection efficiency has been observed in the endcap KLM detector. For present and future high luminosity operations, we have to identify the background source and consider the shielding. To identify the background source, the background data sampled from e/sup +/e/sup -//spl rarr//spl mu//sup +//spl mu//sup -/ events were investigated and the simulations of the sensitivity of the endcap KLM detector to neutrons and /spl gamma/'s as the background sources were performed using the Geant4 simulation toolkit. The comparisons of the simulations with the experimental data are presented.
The Belle detector has been operating at the KEKB colliding beam B-factory since 1999. It is a general purpose detector optimized to measure decay products of
B
B
̄
pairs created at the Y(4S) ...resonance. The vertexing function provided by the Silicon Vertex Detector (SVD) is crucial for accurate
B-decay measurements, particularly in searching for asymmetries in decay times of
B̄ and
B mesons, the essence of CP violation being studied at Belle. High radiation levels during early KEKB running soon rendered “SVD1.0” inoperable. It was replaced by another of the same design, built in parallel with the installation of SVD1.0. Improvement of the beam operating conditions allowed “SVD1.1” to provide vertex information for the first year of operation. During this time “SVD1.4” was built. This was mechanically identical, so needed no new tooling or structure development but used a radiation tolerant 0.8
μm process VA1′ chip and an upgraded detector design from Hamamatsu. SVD1.4 was installed in Belle during the 2000 summer shutdown and has successfully operated since. During this time, the KEKB luminosity has been raised to record values, above 4×10
33
cm
−2, whilst maintaining manageable radiation levels. A new SVD (SVD2) is under development to achieve enhanced radiation tolerance, to increase acceptance to that of the original Belle specification, and to introduce SVD information into the Belle level-1 trigger. This talk will give a status report of the Belle SVD, including performance achieved so far, and provide an overview of the SVD2 upgrade.
Charmless hadronic B decays are suppressed compared to other hadronic B decays and hence can be excellent probes for new physics beyond the Standard Model. We present recent results from Belle on ...B→hh decays where h is a pion or a kaon of any charge, and B→ϕπ decays. The data samples are collected with the Belle detector at the KEKB e+e− collider operating at the ϒ(4S) resonance. The B→hh results, including the branching fractions and CP asymmetries, are based on a full Belle data sample of 772 million BB¯ pairs, while the B→ϕπ results are based on 657 million BB¯ pairs.
PDF
