24 research outputs found
Constraints on light neutrino parameters derived from the study of neutrinoless double beta decay
The study of the neutrinoless double beta () decay mode can
provide us with important information on the neutrino properties, particularly
on the electron neutrino absolute mass. In this work we revise the present
constraints on the neutrino mass parameters derived from the
decay analysis of the experimentally interesting nuclei. We use the latest
results for the phase space factors (PSFs) and nuclear matrix elements (NMEs),
as well as for the experimental lifetimes limits. For the PSFs we use values
computed with an improved method reported very recently. For the NMEs we use
values chosen from literature on a case-by-case basis, taking advantage of the
consensus reached by the community on several nuclear ingredients used in their
calculation. Thus, we try to restrict the range of spread of the NME values
calculated with different methods and, hence, to reduce the uncertainty in
deriving limits for the Majorana neutrino mass parameter. Our results may be
useful to have an up-date image on the present neutrino mass sensitivities
associated with measurements for different isotopes and to
better estimate the range of values of the neutrino masses that can be explored
in the future double beta decay (DBD) experiments.Comment: 11 page
Fast, Efficient Calculations of the Two-Body Matrix Elements of the Transition Operators for Neutrinoless Double Beta Decay
To extract information about the neutrino properties from the study of
neutrinoless double-beta (0\nu\beta\beta) decay one needs a precise computation
of the nuclear matrix elements (NMEs) associated with this process. Approaches
based on the Shell Model (ShM) are among the nuclear structure methods used for
their computation. ShM better incorporates the nucleon correlations, but have
to face the problem of the large model spaces and computational resources. The
goal is to develop a new, fast algorithm and the associated computing code for
efficient calculation of the two-body matrix elements (TBMEs) of the
0\nu\beta{\beta} decay transition operator, which are necessary to calculate
the NMEs. This would allow us to extend the ShM calculations for double-beta
decays to larger model spaces, of about 9-10 major harmonic oscillator shells.
The improvement of our code consists in a faster calculation of the radial
matrix elements. Their computation normally requires the numerical evaluation
of two-dimensional integrals: one over the coordinate space and the other over
the momentum space. By rearranging the expressions of the radial matrix
elements, the integration over the coordinate space can be performed
analytically, thus the computation reduces to sum up a small number of
integrals over momentum. Our results for the NMEs are in a good agreement with
similar results from literature, while we find a significant reduction of the
computation time for TBMEs, by a factor of about 30, as compared with our
previous code that uses two-dimensional integrals.Comment: 6 pages, one figur
Constraints on Heavy Neutrino and SUSY Parameters Derived from the Study of Neutrinoless Double Beta Decay
New constraints on the lepton number violating (LNV) parameters are derived from the analysis of the neutrinoless double beta (0νββ) decay in the hypothesis that this process would occur through the exchange of heavy neutrinos and/or SUSY particles. For derivation, we use new values of both phase space factors (PSFs) and nuclear matrix elements (NMEs) calculated with numerical codes developed recently, as well as the most recent experimental lifetimes. The NMEs are computed with a shell model (ShM) code for  48Ca,  76Ge, and  82Se nuclei, while at present similar ShM results are available only for the first nucleus. We compare our results with similar ones from literature, obtained with ShM, QRPA, and IBM-2 methods, and conclude that more results are needed for a relevant analysis on the validity of NMEs associated with these decay mechanisms
A note on the QFT randomness spectral test a new approach of DST
Quantum computers provide a new way of solving problems even in cryptography in which digital signature make an important role. In this paper, we describe a comparison between the spectral test in classical mode and quantum mode through Fourier Transform. A comparison of the results in the two cases was made. Applications of the proposed techniques are from the field of statistical testing of the pseudorandom bit generators used for cryptographic applications. The proposed statistical test is an extension of the Discrete Fourier Transform statistical test proposed in NIST SP 800-22
Radio-induced brain lesions
Introduction: Radiotherapy, an important tool in multimodal oncologic treatment, can cause radio-induced brain lesion development after a long period of time following irradiation.Material and method: We report 4 cases with radio-induced brain lesions, admitted into the Fourth Department of Neurosurgery, Emergency Clinical Hospital Bagdasar-Arseni, during a 4 years period of time.Results: Two patients had meningiomas and two had unruptured cavernomas. Other side effects of radiotherapy, such as diffuse brain atrophy, leukoencephalopathy, optic atrophy, panhypopituitarism were also noted. The two patients with large meningiomas underwent surgery, with good outcome. Observation was the choice for the two asymptomatic cavernomas. Panhypopituitarism needed synthetic hormonal replacement therapy.Conclusions: Radiotherapy can cause long-term complications and can induce development of new brain lesions into previous radiation area. Meningiomas and cavernomas can be radio-induced brain lesions. Meningiomas can grow to large size, requiring surgery. Unruptured asymptomatic cavernomas can be left in place and patients are followed clinical and with serial imaging. Other findings after radiotherapy are diffuse brain atrophy, leukoencephalopathy, optic atrophy and panhypopituitarism