Measurement of the decay branching ratio (original) (raw)

Measurement of the branching ratio for the decay η→μ+μ−

Physical Review D, 1994

A new measurement of the branching ratio for the decay,.,-+ JJ+ JJ-, made at tile SATURNE II proton synchrotron, resulted in f(,.,-+ JJ+ JJ-)lf(,.,-+ all) = 15.7 ± 0.7 (stat.)±0.5 (syst.)) x 10-8. The reaction pd-+ l He ,., close to threshold yielded 800 S-I tagged ,.,'s in a narrow momentum band around 257 MeV Ic. Muon pairs were detected in two range telescopes. The data obtained consist of 114 events ,.,-+ JJ+ JJ-on a background of 14 events. The new value for the branching ratio is 1.3 ± 0.2 times the unitarity lower limit, consistent with most quark and Vector Meson Dominance models which describe th~ decay as an electromagnetic transition with a two-photon intermediate state. The result resolves the discrepancy between the two previous measurements of this

Measurement of η meson decays into lepton-antilepton pairs

Physical Review D, 2008

A search for rare lepton decays of the η meson was performed using the WASA detector at CELSIUS. Two candidates for double Dalitz decay η → e + e − e + e − events are reported with a background of 1.3±0.2 events. This allows to set an upper limit to the branching ratio of 9.7×10 −5 (90% CL). The branching ratio for the decay η → e + e − γ is determined to (7.8 ± 0.5stat ± 0.8syst) × 10 −3 in agreement with world average value. An upper limit (90% CL) for the branching ratio for the η → e + e − decay is 2.7 × 10 −5 and a limit for the sum of the η → µ + µ − µ + µ − and η → π + π − µ + µ − decays is 3.6 × 10 −4 .

Measurement of Prominent η-Decay Branching Fractions

Physical Review Letters, 2007

The decay ψ(2S) → ηJ/ψ is used to measure, for the first time, all prominent η-meson branching fractions with the same experiment in the same dataset, thereby providing a consistent treatment of systematics across branching fractions. We present results for η decays to γγ, π + π − π 0 , 3π 0 , π + π − γ, and e + e − γ, accounting for 99.9% of all η decays. The precisions for several of the branching fractions and their ratios are improved. Two channels, π + π − γ and e + e − γ, show results that differ at the level of three standard deviations from those previously determined.

Measurement of the ω → ηγ decay branching ratio

Physics Letters B, 1997

We have measured the branching ratio for the radiative decay w + qy with w mesons produced in antiproton-proton annihilation at rest into row and 70. Taking into account p -w mixing we find a branching ratio B(w -+ qy) = (6.6 & 1.7) X 10e4, in accord with the constructive interference solution in other experiments. The upper-limit for the direct radiative decay w --) 3y is I .9 X 10e4 at 95% confidence level. 0 1997 Elsevier Science B.V.

Measurement of the branching ratios for the decays of D_{s}^{+} to ηπ^{+}, η^{′}π^{+}, ηρ^{+}, and η^{′}ρ^{+}

Physical Review D, 1998

Using a data sample with integrated luminosity of 3.9 fb −1 collected in e + e − annihilation with the CLEO-II detector at the Cornell Electron Storage Ring, we have measured the branching ratios for the decay modes D + s → (η, η ′)π + and D + s → (η, η ′)ρ + relative to D + s → φπ +. These decay modes are among the most common hadronic decays of the D + s , and can be related by factorization to the semileptonic decays D + s → (η, η ′)ℓ + ν l. The results obtained are compared with previous CLEO results and with the branching ratios measured for the related semileptonic decays. We also report results on the Cabibbosuppressed decays of the D + to the same final states.

Measurement of the branching ratio and search for a CP violating asymmetry in the η→π+π−e+e−(γ) decay at KLOE

Physics Letters B, 2009

We have studied the η → π + π − e + e − (γ) decay using about 1.7 f b −1 collected by the KLOE experiment at the DAΦNE φ-factory. This corresponds to about 72 millions η mesons produced in φ radiative decays. We have measured the branching ratio, inclusive of radiative effects, with 4% accuracy: BR(η → π + π − e + e − (γ)) = (26.8 ± 0.9 Stat. ± 0.7 Syst.) × 10 −5. We have obtained the first measurement of the CP-odd ππ − ee decay planes angular asymmetry, A φ = (−0.6 ± 2.5 Stat. ± 1.8 Syst.) × 10 −2 .

Evidence for the decay and measurement of the relative branching fractions of meson decays to and

Nuclear Physics B, 2013

Evidence for the decay B 0 → J/ψ ω and measurement of the relative branching fractions of B 0 s meson decays to J/ψ η and J/ψ η The LHCb collaboration † Abstract First evidence of the B 0 → J/ψ ω decay is found and the B 0 s → J/ψ η and B 0 s → J/ψ η decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb −1 collected by the LHCb experiment in proton-proton collisions at a centre-ofmass energy of √ s = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J/ψ ρ 0 decay: