Eur. Phys. J. C 20, 1-11
DOI: 10.1007/s100520100646
4-Neutrino mass schemes and the likelihood of (3+1)-mass spectra
W. Grimus and T. SchwetzUniversität Wien, Institut für Theoretische Physik, Boltzmanngasse 5, 1090 Wien, Austria
(Received: 26 February 2001 / Published online: 25 April 2001 -© Springer-Verlag / Società Italiana di Fisica 2001 )
Abstract
We examine the (3+1)-class of 4-neutrino mass spectra within
a
rigorous statistical analysis based on the
Bayesian approach to probability.
The data of the Bugey, CDHS and KARMEN experiments are combined
by using a likelihood function.
Our statistical approach allows us to incorporate solar
and atmospheric neutrino
data and also the result of the CHOOZ experiment via
inequalities which involve elements of the neutrino
mixing matrix and are derived from these data.
For any short-baseline
we calculate a
bound on the LSND transition amplitude 
and find that, in the
- plane,
there is no overlap between the 99% CL region
allowed by the latest LSND analysis and the region allowed by
our
bound on at 95% CL; there are some small overlap
regions
if we take the bound at 99% CL. Therefore, we conclude
that, with the existing data, the (3+1)-neutrino mass
spectra are not very likely. However, treating the
(2+2)-spectra with our method, we find that they are well compatible
with all data.
© Società Italiana di Fisica, Springer-Verlag 2001
