372 research outputs found
Comparison the effects of oxytocin and methylergonovine in elective caesarean section under spinal anesthesia
Evidence of the Purely Leptonic Decay B- --> tau- nu_tau-bar
We present the first evidence of the decay B- --> tau- nu_tau-bar using 414
fb^-1 of data collected at the Upsilon(4S) resonance with the Belle detector at
the KEKB asymmetric-energy e+e- collider. Events are tagged by fully
reconstructing one of the B mesons in hadronic modes. We detect the signal with
a significance of 3.5 standard deviations including systematics, and measure
the branching fraction to be Br(B- --> tau- nu_tau-bar) = (1.79
+0.56-0.49(stat) +0.46-0.51(syst))*10^-4. This implies that f_B = 0.229
+0.036-0.031(stat) +0.034-0.037(syst) GeV and is the first direct measurement
of this quantity.Comment: 6 pages, 3 figures, to appear in Physical Review Letter
Observation of B0->pi0pi0
We report the first observation of the decay B0->pi0pi0, using a 253/fb data
sample collected at the Upsilon(4S) resonance with the Belle detector at the
KEKB e+e- collider. The measured branching fraction is BF(B0->pi0pi0) = {2.32
+0.4-0.5(stat) +0.2-0.3(syst)} x 10^-6, with a significance of 5.8 standard
deviations including systematic uncertainties. We also make the first
measurement of the direct CP violating asymmetry in this mode.Comment: 6 pages, 2 figures, submitted to ICHEP04, Beijing and Physical Review
Letters. v2: a possible pile-up background is checked and a systematic error
for it is include
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