2,828 research outputs found
Possible improvements on the mass of the tau neutrino using leptonic decays
We show how a very accurate measurement of the branching ratios of the
leptonic decay modes of the mesons can lead to a significant
improvement in the mass limit for the tau neutrino.Comment: 1 typo in Eq.2 correcte
Minimally Allowed Neutrinoless Double Beta Decay Rates From Approximate Flavor Symmetries
Neutrinoless double beta decay () is among the only realistic
probes of Majorana neutrinos. In the standard scenario, dominated by light
neutrino exchange, the process amplitude is proportional to , the
element of the Majorana mass matrix. Naively, current data allows for vanishing
, but this should be protected by an appropriate flavor symmetry. All
such symmetries lead to mass matrices inconsistent with oscillation
phenomenology. I perform a spurion analysis to break all possible Abelian
symmetries that guarantee vanishing rates and search for
minimally allowed values. I survey 230 broken structures to yield
values and current phenomenological constraints under a variety of scenarios.
This analysis also extracts predictions for both neutrino oscillation
parameters and kinematic quantities. Assuming reasonable tuning levels, I find
that eV at 99% confidence. Bounds below this value
might indicate the Dirac neutrino nature or the existence of new light (eV-MeV
scale) degrees of freedom that can potentially be probed elsewhere.Comment: 19 Pages, 4 .eps Figures, 3 Table
Measurement of the proton light response of various LAB based scintillators and its implication for supernova neutrino detection via neutrino-proton scattering
The proton light output function in electron-equivalent energy of various
scintillators based on linear alkylbenzene (LAB) has been measured in the
energy range from 1 MeV to 17.15 MeV for the first time. The measurement was
performed at the Physikalisch-Technische Bundesanstalt (PTB) using a neutron
beam with continuous energy distribution. The proton light output data is
extracted from proton recoil spectra originating from neutron-proton scattering
in the scintillator. The functional behavior of the proton light output is
described succesfully by Birks' law with a Birks constant kB between (0.0094
+/- 0.0002) cm/MeV and (0.0098 +/- 0.0003) cm/MeV for the different LAB
solutions. The constant C, parameterizing the quadratic term in the generalized
Birks law, is consistent with zero for all investigated scintillators with an
upper limit (95% CL) of about 10^{-7} cm^2/MeV^2. The resulting quenching
factors are especially important for future planned supernova neutrino
detection based on the elastic scattering of neutrinos on protons. The impact
of proton quenching on the supernova event yield from neutrino-proton
scattering is discussed.Comment: 12 pages, 17 figures, 4 tables, updated version for publication in
Eur.Phys.J.
A 40th deg and order gravitational field model for Mars
Understanding the origin and evolution of major photographic features on Mars, such as the hemispheric dichotomy and Tharsis rise, will require improved resolution of that planet's gravitational and topographic fields. The highest resolution gravity model for Mars published to date was derived from Doppler tracking data from the Mariner 9 and Viking 1 and 2 spacecraft, and is of 18th degree and order. That field has a maximum spatial resolution of approx. 600 km, which is comparable to that of the best topographic model. The resolution of previous gravity models was limited not by data density, but rather by the computational resources available at the time. Because this restriction is no longer a limitation, the Viking and Mariner data sets were reanalyzed and a gravitational field was derived complete to the 40th degree and order with a corresponding maximum spatial resolution of 300 km where the data permit
A new investigation of half-lives for the decay modes of V
A new search for the decay modes of the 4-fold forbidden non-unique decay of
V has been performed at the Gran Sasso Underground Laboratory (LNGS). In
total an exposure of 197 kg d has been accumulated. The half-life for
the electron capture into the first excited state of Ti has been
measured with the highest precision to date as yr (68% C.I.) in which systematics uncertainties dominate. The search
for the -decay into the first excited state of Cr resulted in a
lower limit of yr (90% C.I.), which is an improvement of
almost one order of magnitude compared to existing results. The sensitivity of
the new measurement is now in the region of theoretical predictions
Lower k-record values from unit-Gompertz distribution and associated inference
Mazucheli et al. (2019) introduced the unit-Gompertz (UG) distribution and
studied some of its properties. More specifically, they considered the random
variable X =exp(-Y), where Y has the Gompertz distribution. In this paper, we
consider the lower k-record values from this distribution. We obtain exact
explicit expressions as well as several recurrence relations for the single and
product moments of lower k-record values and then we use these results to
compute the means, variances and the covariances of the lower k-record values.
We make use of these calculated moments to find the best linear unbiased
estimators (BLUEs) of the location and scale parameters of the UG distribution.
Applying the relation between the BLUE and the best linear invariant estimator
(BLIE), we obtain the BLIEs of the location and scale parameters, as well. In
addition, based on the observed k-records, we investigate how to obtain the
best linear unbiased predictor (BLUP) and best linear invariant predictor
(BLIP) for a future k-record value. Confidence intervals for the unknown
parameters and prediction intervals for future k-records are also discussed. A
simulation study is performed to assess the point and interval estimators and
predictors proposed in the paper. The results show that the BLIE and BLIP
outperform the BLUE and BLIP, in the sense of mean squared error criterion,
respectively. Finally, a real data set pertaining to COVID-19 2-records is
analyzed
An alternative search for the electron capture of Te-123
A search for the electron capture of Te-123 has been performed using CdZnTe
detectors. After a measuring time of 195 h no signal could be found resulting
in a lower half-life limt of yrs (95 % CL) for
this process. This clearly discriminates between existing experimental results
which differ by six orders of magnitude and our data are in strong favour of
the result with longer half-lifes.Comment: 2 pages, 2 eps-figures, reanalysis of data set
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