Measurement of the in-medium modifications of the ∆ resonance, signatures of the excitation of nuclear collective states and the first experimental evidence for a thermal emission of photons have ...been obtained from the analysis of new π± 4He data at Tπ =106 MeV at PAINUC with the PAINUC experiment at JINR. Experimental limits on the direct measurement of the muon neutrino mass is also being studied: the pion mass resolution, at present 350 eV, heavily constrains the accessible mν sector above 419 keV/c2.
Measurement of the in-medium modifications of the Δ resonance has been performed at a PAINUC experiment. Signatures of the excitation of nuclear collective states and the first experimental evidence ...for thermal emission of photons have been obtained from the analysis of the π± 4He data taken at Tπ =106 MeV.
Measurement of the in-medium modifications of the Delta resonance has been performed at a PAINUC experiment. Signatures of the excitation of nuclear collective states and the first experimental ...evidence for thermal emission of photons have been obtained from the analysis of the pi super(+ or -) super(4)He data taken at Tpi = 106 MeV.
On the muon neutrino mass Angelov, N.; Balestra, F.; Batusov, Yu ...
Nuclear physics. A,
12/2006, Letnik:
780, Številka:
1
Journal Article
Recenzirano
Odprti dostop
During the runs of the PS 179 experiment at LEAR of CERN, we photographed an event of antiproton–Ne absorption, with a complete
π
+
→
μ
+
→
e
+
chain. From the vertex of the reaction a very slow ...energy
π
+
was emitted. The
π
+
decays into a
μ
+
and subsequently the
μ
+
decays into a positron. At the first decay vertex a muon neutrino was emitted and at the second decay vertex an electron neutrino and a muon antineutrino. Measuring the pion and muon tracks and applying the momentum and energy conservation and using a classical statistical interval estimator, we obtained an experimental upper limit for the muon neutrino mass:
m
ν
<
2.2
MeV
at a 90% confidence level. A statistical analysis has been performed of the factors contributing to the square value of the neutrino mass, to deduce the possibility to reach experimentally the lowest muon neutrino mass limit from the
π
→
μ
ν
decays.
Measurement of the in-medium modifications of the Delta resonance, signatures of the excitation of nuclear collective states and the first experimental evidence for a thermal emission of photons have ...been obtained from the analysis of new pi super(+ or -) super(4)He data at T sub(pi) = 106 MeV at PAINUC with the PAINUC experiment at JINR. Experimental limits on the direct measurement of the muon neutrino mass is also being studied: the pion mass resolution, at present 350 eV, heavily constrains the accessible mv sector above 419 keV/c super(2).
We have performed the most comprehensive resonance-model fit of π−π−π+ states using the results of our previously published partial-wave analysis (PWA) of a large data set of diffractive-dissociation ...events from the reaction π−+p→π−π−π++precoil with a 190 GeV/c pion beam. The PWA results, which were obtained in 100 bins of three-pion mass, 0.5<m3π<2.5 GeV/c2, and simultaneously in 11 bins of the reduced four-momentum transfer squared, 0.1<t′<1.0 (GeV/c)2, are subjected to a resonance-model fit using Breit-Wigner amplitudes to simultaneously describe a subset of 14 selected waves using 11 isovector light-meson states with JPC=0−+, 1++, 2++, 2−+, 4++, and spin-exotic 1−+ quantum numbers. The model contains the well-known resonances π(1800), a1(1260), a2(1320), π2(1670), π2(1880), and a4(2040). In addition, it includes the disputed π1(1600), the excited states a1(1640), a2(1700), and π2(2005), as well as the resonancelike a1(1420). We measure the resonance parameters mass and width of these objects by combining the information from the PWA results obtained in the 11 t′ bins. We extract the relative branching fractions of the ρ(770)π and f2(1270)π decays of a2(1320) and a4(2040), where the former one is measured for the first time. In a novel approach, we extract the t′ dependence of the intensity of the resonances and of their phases. The t′ dependence of the intensities of most resonances differs distinctly from the t′ dependence of the nonresonant components. For the first time, we determine the t′ dependence of the phases of the production amplitudes and confirm that the production mechanism of the Pomeron exchange is common to all resonances. We have performed extensive systematic studies on the model dependence and correlations of the measured physical parameters.
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