John Kelley, UW-Madison, May 2008
After applying the Nch-dependent cuts described in the previous section, we revisit the observable distributions, Nch and cos(Zenith). We note that these plots are binned more finely than in the likelihood analysis, and we have not normalized MC to data.
The new limits on VLI are presented in figure 9.3. The upper limit at maximal mixing (2.8e-27) is slightly worse, as expected, than the limit calculated after the first unblinding, and it is no longer better than the SuperK+K2K limit. However, it is still a 40% improvement on the previous AMANDA-II limit.
We have also calculated the upper limits for similar VLI and QD models using different energy dependences. The expectation for a signal does not appreciably change -- only the steepness of the new physics transition. We present VLI and QD limits in the table below for effects proportional to E, E^2, and E^3. VLI upper limits are for maximal mixing; QD upper limits are for all decoherence parameters equal. Numbers in bold are the models shown above in the 2D contour plots.
|n||VLI limit||QD limit||Units|
The two-parameter unfolding (or "forward folding") results for the conventional atmospheric flux are presented below. The contours suggest an atmospheric flux that has a slightly higher normalization and spectral slope than the Bartol model (although we do note the latter is extrapolated via NeutrinoFlux past 700 GeV). We are currently checking the results based on the Honda 2006 model to make sure they are comparable.
The 90% contour can be represented as an allowed band of possible fluxes -- the envelope of curves generated by the different allowed normalizations and spectral slopes. The energy region for the band is the intersection of the 5-95% regions for each particular possibility.
Finally, we show a comparison of this result with the 2000-03 Münich et al. unfolding result. The energy ranges are complementary, and the agreement in the overlap region is rather good. The data points describing the 90% allowed forward-folding flux can be found here.