arXiv subjects

BELLE Collaboration

Publications and source records attributed to BELLE Collaboration.

4 recordsLinked to original sources

arXiv2011

Observation of h_b(1P)->eta_b(1S)gamma

We report the first observation of the radiative transition h_b(1P)->eta_b(1S)gamma, where the h_b(1P) is produced in Upsilon(5S)->h_b(1P)pi+pi- dipion transitions. We measure the eta_b(1S) mass to be (9401.0+-1.9+1.4-2.4)MeV/c^2 with a width of (12.4+5.5-4.6+11.5-3.4)MeV and a decay branching fraction of BF[h_b(1P)->eta_b(1S)gamma]=(49.8+-6.8+10.9-5.2)%. The measured eta_b(1S) mass corresponds to a hyperfine splitting of (59.3+-1.9+2.4-1.4)MeV/c^2. This value deviates significantly from the current world average obtained from measurements of Upsilon(3S)->eta_b(1S)gamma and Upsilon(2S)->eta_b(1S)gamma reactions. We also report updated results for the h_b(1P) mass (9899.0+-0.4+-1.0)MeV/c^2 and its hyperfine splitting (0.8+-1.1)MeV/c^2. These measurements are performed using a 121.4fb^-1 data sample collected at the peak of the Upsilon(5S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.

hep-ex↗

arXiv2008

Improved search for D^0 mixing using semileptonic decays at Belle

A search for mixing in the neutral D meson system has been performed using semileptonic D0 -> K(*)- e+ νand D0 -> K(*)- μ+ νdecays. Neutral D mesons from D*+ -> D0 π_s^+ decays are used and the flavor at production is tagged by the charge of the slow pion. The measurement is performed using 492 fb^-1 of data recorded by the Belle detector. From the yield of right-sign and wrong-sign decays arising from non-mixed and mixed events, respectively, we measure the ratio of the time-integrated mixing rate to the unmixed rate to be R_M = (1.3 +- 2.2 +- 2.0) x 10^-4. This corresponds to an upper limit of R_M < 6.1 x 10^-4 at the 90% C.L.

hep-ex↗

arXiv2007

Search for B0 -> rho0rho0 and Non-Resonant B0 -> 4pi Decays

We search for the decay B0 -> rho0rho0 and other possible charmless modes with a pi+pi-pi+pi- final state, including B0 -> rho0f0(980), B0 -> f0(980)f0(980), B0 -> f0(980)pipi, B0 -> rho0pipi and non-resonant B0 -> 4pi. These results are obtained from a data sample containing 520 x 10^6 BBar pairs collected by the Belle detector at the KEKB asymmetric-energy e+e- collider. We measure a branching fraction of (0.9 +/- 0.4^{+0.3}_{-0.4}) x 10^{-6}, or B(B0 -> rho0rho0) < 1.6 x 10^{-6} at the 90% confidence level. The significance including systematic uncertainties is 1.8σ. These values correspond to the final state being longitudinally polarized. We also measure the branching fraction of non-resonant B0 -> 4pi decay to be (10.2 +/- 4.7^{+2.3}_{-1.5}) x 10^{-6} with 2.1σsignificance, and set the 90% confidence level upper limit B(B0 -> 4pi) < 17.3 x 10^{-6}. For the other related decays, B0 -> rho0f0(980), B0 -> f0(980)f0(980), B0 -> f0(980)pipi and B0 -> rho0pipi, no significant signals are observed and upper limits on the branching fractions are set.

hep-ex↗

arXiv2005

Measurements of Branching Fraction and Polarization in B^+ -> rho^+ K^{*0} Decay

We present the results of a study of the charmless vector-vector decay $B^+\to ρ^+K^{*0}$, based on 253 fb$^{-1}$ of data collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We obtain the branching fraction ${\cal B}(B^+\toρ^+ K^{*0})=(8.9\pm 1.7(\rm stat)\pm 1.2 (\rm syst))\times 10^{-6}$. We also perform a helicity analysis of the $ρ$ and $K^*$ vector mesons, and obtain the longitudinal polarization fraction $f_L(B^+\to ρ^+ K^{*0})=0.43 \pm 0.11(\rm stat)^{+0.05}_{-0.02}(\rm syst)$.

hep-ex↗