RESUMO
We report on a search for CP violation in τ(±)âK(S)(0)π(±)ν(τ) decays using a data sample of 699 fb(-1) collected by the Belle experiment at the KEKB electron-positron asymmetric-energy collider. The CP asymmetry is measured in four bins of the invariant mass of the K(S)(0)π(±) system and found to be compatible with zero with a precision of O(10(-3)) in each mass bin. Limits for the CP violation parameter Im(η(S)) are given at the 90% confidence level. These limits are |Im(η(S))| < 0.026 or better, depending on the parametrization used to describe the hadronic form factors, and improve upon previous limits by 1 order of magnitude.
RESUMO
We search for dimuon decays of a low mass particle in the decays B0âK*0 X and B0âρ0 X using a data sample of 657×10(6)BB events collected with the Belle detector at the KEKB asymmetric-energy e+ e- collider. We find no evidence for such a particle in the mass range from 212 MeV/c2 to 300 MeV/c2 for lifetimes below 10(-12) s, and set upper limits on its branching fractions. In particular, we search for a particle with a mass of 214.3 MeV/c2 reported by the HyperCP experiment, and obtain upper limits on the products B(B0âK*0 X)×B(Xâµ+ µ- )<2.26(2.27)×10(-8) and B(B0âρ0 X)×B(Xâµ+ µ-)<1.73(1.73)×10(-8) at 90% C.L. for a scalar (vector) X particle.
Assuntos
Modelos Químicos , Nanopartículas/química , Física Nuclear , Algoritmos , Transferência de Energia , Íons , Aceleradores de PartículasRESUMO
We report the results of a search for a charmoniumlike state produced in the process gammagamma-->omegaJ/psi in the 3.9-4.2 GeV/c{2} mass region. We observe a significant enhancement, which is well described by a resonant shape with mass M=(3915+/-3+/-2) MeV/c{2} and total width Gamma=(17+/-10+/-3) MeV. This enhancement may be related to one or more of the three charmoniumlike states so far reported in the 3.90-3.95 GeV/c{2} mass region.