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Register a new userGlobal oscillation data analysis on the $3 u$ mixing without unitarity
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We present results of a combined analysis in neutrino oscillations without unitarity assumption in the $3 u$ mixing picture. Constraints on neutrino mixing matrix elements are based on recent data from the reactor, solar and long-baseline accelerator neutrino oscillation experiments. The current data are consistent with the standard $3 u$ scheme. The precision on different matrix elements can be as good as a few percent at $3sigma$ CL, and is mainly limited by the experimental statistical uncertainty. The $ u_e$ related elements are the most precisely measured among all sectors with the uncertainties $<20%$. The measured leptonic CP violation is very close to the one assuming the standard $3 u$ mixing. The deviations on normalization and the unitarity triangle closure are confined within $mathcal{O}(10^{-3})$, $mathcal{O}(10^{-2})$ and $mathcal{O}(10^{-1})$, for $ u_e$, $ u_{mu}$ and $ u_{tau}$ sectors, respectively. We look forward to the next-generation neutrino oscillation experiments textit{such as} DUNE, T2HK, and JUNO, especially the precise measurements on $ u_tau$ oscillations, to significantly improve the precision of unitarity test on the $3 u$ mixing matrix.
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We present experimentally derived potential curves and spin-orbit interaction functions for the strongly perturbed $A^{1}Sigma_{u}^{+}$ and $b^{3}Pi_{u}$ states of the cesium dimer. The results are based on data from several sources. Laser-induced fluorescence Fourier transform spectroscopy (LIF FTS) was used some time ago in the Laboratoire Aim{e} Cotton primarily to study the $X ^{1}Sigma_{g}^{+}$ state. More recent work at Tsinghua University provides information from moderate resolution spectroscopy on the lowest levels of the $b^{3}Pi_{0u}^{pm}$ states as well as additional high resolution data. From Innsbruck University, we have precision data obtained with cold Cs$_{2}$ molecules. Recent data from Temple University was obtained using the optical-optical double resonance polarization spectroscopy technique, and finally, a group at the University of Latvia has added additional LIF FTS data. In the Hamiltonian matrix, we have used analytic potentials (the Expanded Morse Oscillator form) with both finite-difference (FD) coupled-channels and discrete variable representation (DVR) calculations of the term values. Fitted diagonal and off-diagonal spin-orbit functions are obtained and compared with {it ab initio} results from Temple and Moscow State universities.
The unitarity of the lepton mixing matrix is a critical assumption underlying the standard neutrino-mixing paradigm. However, many models seeking to explain the as-yet-unknown origin of neutrino masses predict deviations from unitarity in the mixing of the active neutrino states. Motivated by the prospect that future experiments may provide a precise measurement of the lepton mixing matrix, we revisit current constraints on unitarity violation from oscillation measurements and project how next-generation experiments will improve our current knowledge. With the next-generation data, the normalizations of all rows and columns of the lepton mixing matrix will be constrained to $lesssim$10% precision, with the $e$-row best measured at $lesssim$1% and the $tau$-row worst measured at ${sim}10%$ precision. The measurements of the mixing matrix elements themselves will be improved on average by a factor of $3$. We highlight the complementarity of DUNE, T2HK, JUNO, and IceCube Upgrade for these improvements, as well as the importance of $ u_tau$ appearance measurements and sterile neutrino searches for tests of leptonic unitarity.
Neutrino non-standard interactions (NSI) with the first generation of standard model fermions can span a parameter space of large dimension and exhibit degeneracies that cannot be broken by a single class of experiment. Oscillation experiments, together with neutrino scattering experiments, can merge their observations into a highly informational dataset to combat this problem. We consider combining neutrino-electron and neutrino-nucleus scattering data from the Borexino and COHERENT experiments, including a projection for the upcoming coherent neutrino scattering measurement at the CENNS-10 liquid argon detector. We extend the reach of these data sets over the NSI parameter space with projections for neutrino scattering at a future multi-ton scale dark matter detector and future oscillation measurements from atmospheric neutrinos at the Deep Underground Neutrino Experiment (DUNE). In order to perform this global analysis, we adopt a novel approach using the copula method, utilized to combine posterior information from different experiments with a large, generalized set of NSI parameters. We find that the contributions from DUNE and a dark matter detector to the Borexino and COHERENT fits can improve constraints on the electron and quark NSI parameters by up to a factor of 2 to 3, even when relatively many NSI parameters are left free to vary in the analysis.
Recently, the first ever lattice computation of the $gamma W$-box radiative correction to the rate of the semileptonic pion decay allowed for a reduction of the theory uncertainty of that rate by a factor of $sim3$. A recent dispersion evaluation of the $gamma W$-box correction on the neutron also led to a significant reduction of the theory uncertainty, but shifted the value of $V_{ud}$ extracted from the neutron and superallowed nuclear $beta$ decay, resulting in a deficit of the CKM unitarity in the top row. A direct lattice computation of the $gamma W$-box correction for the neutron decay would provide an independent cross-check for this result but is very challenging. Before those challenges are overcome, we propose a hybrid analysis, converting the lattice calculation on the pion to that on the neutron by a combination of dispersion theory and phenomenological input. The new prediction for the universal radiative correction to free and bound neutron $beta$-decay reads $Delta_R^V=0.02477(24)$, in excellent agreement with the dispersion theory result $Delta_R^V=0.02467(22)$. Combining with other relevant information, the top-row CKM unitarity deficit persists.
The quartic gauge boson couplings in the ${SU(3)}_C otimes {SU(3)}_L otimes {U(1)}_N$ models are presented. We find that the couplings of four {it differrent} gauge bosons may have unusual Lorentz structure and the couplings sastify the tree unitarity requirement at high energy limit.
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