We report a precise measurement of the masses of the Ξc(2645) and Ξc(2815) baryons using a data sample of 414 fb−1 collected by the Belle Collaboration at the KEKB e+e− collider. The states ...Ξc(2645)0,+ are observed in the Ξc+,0π−,+ decay modes, while the Ξc(2815)0,+ are reconstructed in the Ξc(2645)+,0π−,+ decay modes. The following mass splittings are determined: mΞc(2645)+−mΞc(2645)0=(−0.1±0.3(stat)±0.6(syst)) MeV/c2 and mΞc(2815)+−mΞc(2815)0=(−3.4±1.9(stat)±0.9(syst)) MeV/c2 with a much better precision than the current world averages. We also observe a new decay mode, Ξc(2980)0,+→Ξc(2645)+,0π−,+.
We report on a search for heavy neutrinos (
ν
4) produced in the decay
D
s
→
τν
4 at the SPS proton target followed by the decay
ν
4→
ν
τ
e
+
e
− in the NOMAD detector. Both decays are expected to ...occur if
ν
4 is a component of
ν
τ
. From the analysis of the data collected during the 1996–1998 runs with 4.1×10
19 protons on target, a single candidate event consistent with background expectations was found. This allows to derive an upper limit on the mixing strength between the heavy neutrino and the tau neutrino in the
ν
4 mass range from 10 to 190 MeV. Windows between the SN1987a and Big Bang Nucleosynthesis lower limits and our result are still open for future experimental searches. The results obtained are used to constrain an interpretation of the time anomaly observed in the KARMEN1 detector.
Evidence for B¯s0→Λc+Λ¯π Adachi, I.; Asner, D. M.; Aushev, T. ...
Physics letters. B,
08/2013, Letnik:
726, Številka:
1-3
Journal Article
Recenzirano
Odprti dostop
Using 121.4 fb–1 of data collected with the Belle detector at the Y(5S) resonance at the KEKB asymmetric-energy e+e- collider, we report evidence for the B¯$^{0}_{s}$ → Λ$^{+}_{c}$Λ¯π– decay mode ...with a measured branching fraction (3.6 ± 1.1stat.$^{+0.3}_{-0.5}$syst. ± 0.9Λ$^{+}_{c}$ ± 0.7 NB¯$^{0}_{s}$) x 10–4 and a significance of 4.4 standard deviations. Here, this is the first evidence for a baryonic B$^{0}_{s}$ decay.
Prediction of neutrino fluxes in the NOMAD experiment Astier, P; Autiero, D; Baldo-Ceolin, M ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2003, Letnik:
515, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The method developed for the calculation of the flux and composition of the West Area Neutrino Beam used by NOMAD in its search for neutrino oscillations is described. The calculation is based on ...particle production rates computed using a recent version of FLUKA and modified to take into account the cross-sections measured by the SPY and NA20 experiments. These particles are propagated through the beam line taking into account the material and magnetic fields they traverse. The neutrinos produced through their decays are tracked to the NOMAD detector. The fluxes of the four neutrino flavours at NOMAD are predicted with an uncertainty of about 8% for νμ and νe, 10% for ν̄μ, and 12% for ν̄e. The energy-dependent uncertainty achieved on the νe/νμ prediction needed for a νμ→νe oscillation search ranges from 4% to 7%, whereas the overall normalization uncertainty on this ratio is 4.2%.
Using kaon secondary interactions in the material of the Belle detector, we search for both inclusive and exclusive production of the Θ(1540)+. We set an upper limit of 2.5% at the 90% C.L. on the ...ratio of the Θ(1540)+ to Λ(1520) inclusive production cross sections. We also search for the Θ(1540)+ as an intermediate resonance in the charge exchange reaction K+n→pKS0. We set an upper limit of ΓΘ+<0.64 MeV at the 90% C.L. for mΘ+=1.539 MeV/c2. These results are obtained from a 397 fb−1 data sample collected with the Belle detector near the ϒ(4S) resonance, at the KEKB asymmetric energy e+e− collider.
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