6 research outputs found
Measurements of Branching Fractions and CP Asymmetries in Decays of a B Meson to Two Phi Mesons and a K Meson
We present measurements of the decays B+ to phi phi K+ and B0 to phi phi K0 using about 464 million BBbar pairs collected by the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. We report the branching fractions of the decays B+ to phi phi K+ and B0 to phi phi K0, and CP asymmetry in the charged B mode for phi phi invariant mass below 2.85 GeV/c2:B(B0 to phi phi K0)=(4.5±0.8±0.3)×10-6,B(B+ to phi phi K+)=(5.6±0.5±0.3)×10-6,Ach(B+ to phi phi K+) = - 0.10 ± 0.08 ± 0.02.Additionally, we measure the direct CP asymmetry in B+ to phi phi K+ for phi phi invariant mass within the eta_c resonance region ([2.94 - 3.02] GeV/c2):Ach(B+ to phi phi K+) = - 0.09 ± 0.10 ± 0.02.No direct CP asymmetry is observed both below the eta_c and within the eta_c resonance, as expected within the Standard Model.In each case the uncertainties are statistical and systematic, respectively
The BABAR detector: Upgrades, operation and performance
The BaBar detector operated successfully at the PEP-II asymmetric e+e− collider at the SLAC National Accelerator Laboratory from 1999 to 2008. This report covers upgrades, operation, and performance of the collider and the detector systems, as well as the trigger, online and offline computing, and aspects of event reconstruction since the beginning of data taking
Measurement of the branching fractions for Cabibbo-suppressed decays and at Belle
International audienceWe present measurements of the branching fractions for the singly Cabibbo-suppressed decays and , and the doubly Cabibbo-suppressed decay , based on 980 of data recorded by the Belle experiment at the KEKB collider. We measure these modes relative to the Cabibbo-favored modes and . Our results for the ratios of branching fractions are , , and , where the uncertainties are statistical and systematic, respectively. The second value corresponds to , where is the Cabibbo angle; this value is larger than other measured ratios of branching fractions for a doubly Cabibbo-suppressed charm decay to a Cabibbo-favored decay. Multiplying these results by world average values for and yields , , and , where the third uncertainty is due to the branching fraction of the normalization mode. The first two results are consistent with, but more precise than, the current world averages. The last result is the first measurement of this branching fraction
Measurement of the production ratio in collisions at the resonance using decays at Belle
We measure the ratio of branching fractions for the decays to and using and samples, where stands for ( or ), with fb of data collected at the resonance with the Belle detector. We find the decay rate ratio of over to be , which is the most precise measurement to date. The first and second uncertainties are statistical and systematic, respectively, and the third uncertainty is systematic due to the assumption of isospin symmetry in
Test of light-lepton universality in decays with the Belle II experiment
International audienceWe present a measurement of the ratio of branching fractions of the lepton decaying to muons or electrons using data collected with the Belle II detector at the SuperKEKB collider. The sample has an integrated luminosity of 362 fb at a centre-of-mass energy of 10.58 GeV. Using an optimised event selection, a binned maximum likelihood fit is performed using the momentum spectra of the electron and muon candidates. The result, , where the first uncertainty is statistical and the second is systematic, is the most precise to date. It provides a stringent test of the light-lepton universality, translating to a ratio of the couplings of the muon and electron to the boson in decays of , in agreement with the standard model expectation of unity