17 research outputs found
Comparison of Atmospheric Neutrino Flux Calculations at Low Energies
We compare several different calculations of the atmospheric neutrino flux in
the energy range relevant for contained neutrino interactions, and we identify
the major sources of difference among the calculations. We find nothing that
would affect the predicted ratio of , which is nearly the same
in all calculations. Significant differences in normalization arise primarily
from different treatment of pion production by interactions of protons in the
atmosphere. Different assumptions about the primary spectrum and treatment of
the geomagnetic field are also of some importance.Comment: 15 pages, RevTeX , 5 postscript figures, submitted to Phys. Rev.
Study of the process in the energy region 400<\sqrt[]{s}<1000 MeV
The cross section of the process e^+e^-\to \pi^+\pi^- was measured in the SND
experiment at the VEPP-2M collider in the energy region 400<\sqrt[]{s}<1000
MeV. This measurement was based on about 12.4 \times 10^6 selected collinear
events, which include 7.4\times 10^6 e^+e^-\to e^+e^-, 4.5\times 10^6
e^+e^-\to\pi^+\pi^- and 0.5\times 10^6 e^+e^-\to\mu^+\mu^- selected events. The
systematic uncertainty of the cross section determination is 1.3 %. The
\rho-meson parameters were determined: m_\rho=774.9\pm 0.4\pm 0.5 MeV,
\Gamma_\rho=146.5\pm 0.8\pm 1.5 MeV, \sigma(\rho\to\pi^+\pi^-)=1220\pm 7\pm 16
nb as well as the parameters of the G-parity suppressed decay
\omega\to\pi^+\pi^-: \sigma(\omega\to\pi^+\pi^-)=29.9\pm 1.4\pm 1.0 nb and
\phi_{\rho\omega} = 113.5\pm 1.3\pm 1.7 degree.Comment: 30 pages REVTEX and 31 figure