相关论文: Precise Nucleosynthesis Limits on Neutrino Masses

Active-sterile neutrino mixing is strongly constrained for m_s > 100 keV to avoid excessive energy losses from supernova cores. For smaller m_s, matter effects suppress the effective mixing angle except for a resonant range of energies…

We discuss single heavy neutrino production e+ e- -> N nu -> l W nu, l = e, mu, tau, at a future high energy collider like CLIC, with a centre of mass energy of 3 TeV. This process could allow to detect heavy neutrinos with masses of 1-2…

In this talk I review the present bounds on the tau neutrino, concentrating on the possibility of bringing the mass bound below an MeV.

Based on recent improvements of the supernova electron antineutrino emission model, we update the limit on neutrino mass from the SN1987A data collected by Kamiokande-II, IMB and Baksan. We derive the limit of 5.8 eV at 95 % CL, that we…

We use the scale of neutrino mass to derive model-independent naturalness constraints on possible contributions to muon decay Michel parameters from new physics above the electroweak symmetry-breaking scale. Focusing on Dirac neutrinos, we…

We take a fresh look at the limits on the number of neutrino flavors derived from big bang nucleosynthesis. In particular, recent measurements of the \he4 abundance enable one to estimate the primordial \he4 mass fraction at $Y_p = 0.232…

The Majorana nature of neutrinos can be experimentally verified only via {\it lepton-number} violating processes involving charged leptons. We study 36 lepton-number violating ($\lv$) processes from the decays of tau leptons and…

We investigate the impact of prior models on the upper bound of the sum of neutrino masses, $\sum m_{\nu}$. We use data from Large Scale Structure of galaxies, Cosmic Microwave Background, Type Ia SuperNovae, and Big Bang Nucleosynthesis.…

We investigate the nature (Dirac vs. Majorana) and size of left-handed neutrino masses in a supersymmetric five-dimensional model compactified in the interval [0,\pi R], where quarks and leptons are localized on the boundaries while the…

We analyze the effect of a variation of the strange nucleon matrix element $\langle N| m_s \bar{s}s|N\rangle$ on the abundances of the light elements produced in the Big Bang. For that, we vary the nucleon mass in the leading eight…

We include correlations between elemental abundances in a Monte Carlo statistical analysis of BBN predictions, which, along with updated reaction rates and an improved BBN code, lead to tightened constraints on $\Omega_{B}$ and $N_{\nu}$.…

We consider the case of very low reheating scenarios ($T_{\rm RH}\sim\mathcal{O}({\rm MeV})$) with a better calculation of the production of the relic neutrino background (with three-flavor oscillations). At 95% confidence level, a lower…

If heavy neutrinos with mass $m_{\nu_{H}}\geq$2$ m_e $ are produced in the Sun via the decay ${^8\rm{B}} \rightarrow {^8\rm{Be}} + e^+ + \nu_H$ in a side branch of pp-chain, they would undergo the observable decay into an electron, a…

Sterile neutrinos of mass up to a few tens of TeV can saturate the present experimental bound of neutrinoless double beta decay process. Due to the updated nuclear matrix elements, the bound on mass and mixing angle is now improved by one…

We study possible contributions of heavy sterile neutrinos $\nu_h$ to the decays $\tau^-\to e^{\pm}(\mu^{\pm})\pi^{\mp}\pi^-$. From the experimental upper bounds on their rates we derive new constraints on the $\nu_h-\nu_{\tau}$ mixing in…

Combined results on $\nu_{\mu}\to \nu_{\tau}$ oscillations and $\nu e$-scattering from the Super-Kamiokande and LAMPF experiments, respectively, limit the Dirac $\nu_{\tau}$ diagonal magnetic moment to $\mu_{\nu_{\tau}} < 1.9\times 10^{-9}…

After the electroweak symmetry breaking, we can write down two types of mass for the Standard Model neutrinos, Dirac or Majorana. It is often said that both types of mass cannot be distinguished in neutrino oscillation phenomena. This is in…

Light Dirac neutrino of mass of mass of the order of few eV is obtained in an $SU(2)_L\times U(1)_Y$ model with an extended Higgs sector and right-handed neutrinos. Small neutrino mass is generated at the tree level through small effective…

We demonstrate that Dirac neutrino masses in the experimentally preferred range are generated within supersymmetric gauge extensions of the Standard Model with a generalized supersymmetry breaking sector. If the usual superpotential Yukawa…

A solution for the neutrino mass and mixing pattern is proposed which is compatible with all available experimental data on neutrino oscillations. This solution involves Majorana neutrinos of the pseudo-Dirac type, i.e. m_Majorana <<…