Observational Constraints on Secret Neutrino Interactions from Big Bang Nucleosynthesis

We investigate possible interactions between neutrinos and massive scalar bosons via $g^{}_{\phi} \overline{\nu} \nu \phi$ (or massive vector bosons via $g^{}_V \overline{\nu} \gamma^\mu \nu V^{}_\mu$) and explore the allowed parameter space of the coupling constant $g^{}_{\phi}$ (or $g^{}_V$) and the scalar (or vector) boson mass $m^{}_\phi$ (or $m^{}_V$) by requiring that these secret neutrino interactions (SNIs) should not spoil the success of Big Bang nucleosynthesis (BBN). Incorporating the SNIs into the evolution of the early Universe in the BBN era, we numerically solve the Boltzmann equations and compare the predictions for the abundances of light elements with observations. It turns out that the constraint on $g^{}_{\phi}$ and $m^{}_\phi$ in the scalar-boson case is rather weak, due to a small number of degrees of freedom. However, in the vector-boson case, the most stringent bound on the coupling $g^{}_V \lesssim 6\times 10^{-10}$ at $95~\%$ confidence level is obtained for $m^{}_V \simeq 1~{\rm MeV}$, while the bound becomes much weaker $g^{}_V \lesssim 8\times 10^{-6}$ for smaller masses $m^{}_V \lesssim 10^{-4}~{\rm MeV}$. Moreover, we discuss in some detail how the SNIs affect the cosmological evolution and the abundances of the lightest elements.Comment: 18 pages, 5 figure

Therblig-embedded value stream mapping method for lean energy machining

To improve energy efficiency, extensive studies have focused on the cutting parameters optimization in the machining process. Actually, non-cutting activities (NCA) occur frequently during machining and this is a promising way to save energy through optimizing NCA without changing the cutting parameters. However, it is difficult for the existing methods to accurately determine and reduce the energy wastes (EW) in NCA. To fill this gap, a novel Therblig-embedded Value Stream Mapping (TVSM) method is proposed to improve the energy transparency and clearly show and reduce the EW in NCA. The Future-State-Map (FSM) of TVSM can be built by minimizing non-cutting activities and Therbligs. By implementing the FSM, time and energy efficiencies can be improved without decreasing the machining quality, which is consistent with the goal of lean energy machining. The method is validated by a machining case study, the results show that the total energy is reduced by 7.65%, and the time efficiency of the value-added activities is improved by 8.12% , and the energy efficiency of value-added activities and Therbligs are raised by 4.95% and 1.58%, respectively. This approach can be applied to reduce the EW of NCA, to support designers to design high energy efficiency machining processes during process planning

Tentative sensitivity of future 0νββ0\nu \beta\beta-decay experiments to neutrino masses and Majorana CP phases

In the near future, the neutrinoless double-beta ($0\nu\beta\beta$) decay experiments will hopefully reach the sensitivity of a few ${\rm meV}$ to the effective neutrino mass $|m^{}_{\beta\beta}|$. In this paper, we tentatively examine the sensitivity of future $0\nu\beta\beta$-decay experiments to neutrino masses and Majorana CP phases by following the Bayesian statistical approach. Provided experimental setups corresponding to the sensitivity of $|m^{}_{\beta\beta}| \simeq 1~{\rm meV}$, the null observation of $0\nu\beta\beta$ decays in the case of normal neutrino mass ordering leads to a very competitive bound on the lightest neutrino mass $m^{}_1$. Namely, the $95\%$ credible interval turns out to be $1.6~{\rm meV} \lesssim m^{}_1 \lesssim 7.3~{\rm meV}$ or $0.3~{\rm meV} \lesssim m^{}_1 \lesssim 5.6~{\rm meV}$ when the uniform prior on $m^{}_1/{\rm eV}$ or on $\log^{}_{10}(m^{}_1/{\rm eV})$ is adopted. Moreover, one of two Majorana CP phases is strictly constrained, i.e., $140^\circ \lesssim \rho \lesssim 220^\circ$ for both priors of $m^{}_1$. In contrast, if a relatively worse sensitivity of $|m^{}_{\beta\beta}| \simeq 10~{\rm meV}$ is assumed, the constraint becomes accordingly $0.6~{\rm meV} \lesssim m^{}_1 \lesssim 26~{\rm meV}$ or $0 \lesssim m^{}_1 \lesssim 6.1~{\rm meV}$, while two Majorana CP phases will be essentially unconstrained. In the same statistical framework, the prospects for the determination of neutrino mass ordering and the discrimination between Majorana and Dirac nature of massive neutrinos in the $0\nu\beta\beta$-decay experiments are also discussed. Given the experimental sensitivity of $|m^{}_{\beta\beta}| \simeq 10~{\rm meV}$ (or $1~{\rm meV}$), the strength of evidence to exclude the Majorana nature under the null observation of $0\nu\beta\beta$ decays is found to be inconclusive (or strong), no matter which of two priors on $m^{}_1$ is taken.Comment: 17 pages, 4 figures, more discussions added, matches the published version in JHE