The Collins effect connects transverse quark spin with a measurable azimuthal dependence in the yield of hadronic fragments around the quark's momentum vector. Using two different reconstruction ...methods, we find evidence of statistically significant azimuthal asymmetries for charged pion pairs in e(+)e(-) annihilation at a center-of-mass energy of 10.52 GeV, which can be attributed to a transverse polarization of the primordial quarks. The measurement was performed using a sample of 79 x 10(6) hadronic events collected with the Belle detector.
Using aerogel as radiator and 64-channel flat panel multi-anode PMTs (Hamamatsu H8500) for photon detection, a proximity focusing Cherenkov ring imaging detector has been constructed and tested in ...the KEK
π2 beam. The single photon resolution obtained in the tests (typically around
11
mrad
) is well approximated by estimates of contributions from pixel size and emission point uncertainty. The number of detected photons per Cherenkov ring, typically about 6 for a
2
cm
thick aerogel radiator tile, is in good agreement with estimates based on aerogel and detector characteristics. The detector allows a very efficient separation of kaons and pions at
4
GeV/c
.
We report on a search for the lepton flavor violating τ−→μ−γ and τ−→e−γ decays based on 535 fb−1 of data accumulated at the Belle experiment. No signal is found and we set 90% confidence level upper ...limits on the branching ratios B(τ−→μ−γ)<4.5×10−8 and B(τ−→e−γ)<1.2×10−7.
We report a measurement of the exclusive e+e- -->D(*)+/-D*-/+ cross section as a function of center-of-mass energy near the D(*)+/-D*-/+ threshold with initial-state radiation. A partial ...reconstruction technique is used to increase the efficiency and to suppress background. The analysis is based on a data sample collected with the Belle detector with an integrated luminosity of 547.8 fb(-1).
Status of the Belle silicon vertex detector Natkaniec, Z.; Aihara, H.; Asano, Y. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2006, Letnik:
560, Številka:
1
Journal Article
Recenzirano
The old silicon vertex detector (SVD1) of the Belle detector, operating at the high-luminosity asymmetric energy e+e− collider KEKB, was replaced by an upgraded version (SVD2) in 2003. The new ...detector has modified geometry and redesigned readout electronics, providing a larger polar angle acceptance, better vertex resolution, improved radiation hardness and reduced dead time. The operation of the detector started successfully in October 2003. The basic concepts of the SVD2 design as well as its performance after 10 months of data taking are described in this paper.
We report the observation of an isotriplet of excited charmed baryons, decaying into Lambda(+)(c)pi(-), Lambda(+)(c)pi(0), and Lambda(+)(c)pi(+). We measure the mass differences ...M(Lambda(+)(c)pi)-M(Lambda(+)(c)) and widths to be 515.4(+3.2+2.1)(-3.1-6.0) MeV/c(2), 61(+18+22)(-13-13) MeV for the neutral state; 505.4(+5.8+12.4)(-4.6-2.0) MeV/c(2), 62(+37+52)(-23-38) MeV for the charged state; and 514.5(+3.4+2.8)(-3.1-4.9) MeV/c(2), 75(+18+12)(-13-11) MeV for the doubly charged state, where the uncertainties are statistical and systematic, respectively. These results are obtained from a 281 fb(-1) data sample collected with the Belle detector near the Upsilon(4S) resonance, at the KEKB asymmetric energy e(+)e(-) collider.
We present measurements of decay amplitudes and triple-product correlations in B{yields}{phi}K* decays based on 253 fb{sup -1} of data recorded at the {upsilon}(4S) resonance with the Belle detector ...at the KEKB e{sup +}e{sup -} storage ring. The decay amplitudes for the three different helicity states are determined from the angular distributions of final-state particles. The longitudinal polarization amplitudes are found to be 0.45{+-}0.05{+-}0.02 for B{sup 0}{yields}{phi}K*{sup 0} and 0.52{+-}0.08{+-}0.03 for B{sup +}{yields}{phi}K*{sup +} decays. CP- and T-odd CP-violating triple-product asymmetries are measured to be consistent with zero.
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