Unitarity of the $3\times 3$ lepton flavor mixing matrix $V$ is unavoidably violated in a seesaw mechanism if its new heavy degrees of freedom are slightly mixed with the active neutrino flavors. We propose to use the atomic transition process ${\left| \rm e \right> \to\left|\rm g \right> + γ+ ν^{}_{i} + \overlineν^{}_{j}}$ (for $i, j = 1, 2, 3$), where $\left|\rm e \right>$ and $\left|\rm g \right>$ stand respectively for the excited and ground levels of an atomic system, to probe or constrain the unitarity-violating effects of $V$. We find that the photon spectrum of this transition will be distorted by the effects of $V V^\dagger \neq {\bf 1}$ and $V^\dagger V \neq {\bf 1}$ as compared with the $V V^\dagger = V^\dagger V = {\bf 1}$ case. We locate certain frequencies in the photon spectrum to minimize the degeneracy of effects of the unitarity violation and uncertainties of the flavor mixing parameters themselves. The requirements of a nominal experimental setup to test the unitarity of $V$ are briefly discussed.
Non-unitarity of the leptonic mixing matrix in the TeV-scale type-I seesaw model
轻子味混合中的非么正性效应被认为是I型跷跷板模型的一般特征之一。因此,我们探讨了这些影响TeV规模的I型跷跷板模型,并表明存在非平凡的相关性之间的非么正性参数,源于典型的风味结构的低规模的跷跷板模型。一般来说,从分析讨论和数值结果可以看出,所有六个非么正性参数都与三个模型参数有关,而广泛研究的参数η e τ和η μ τ不是唯象意义的
We present results of a combined analysis in neutrino oscillations without unitarity assumption in the $3ν$ 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 $3ν$ scheme. The precision on different matrix elements can be as good as a few percent at $3σ$ CL, and is mainly limited by the experimental statistical uncertainty. The $ν_e$ related elements are the most precisely measured among all sectors with the uncertainties…
Geometric representation of CP phases $δ_{\rm PDG}, δ_{\rm KM}$ in flavor mixing matrix and its sum rule by alternative unitarity triangle and quadrangle
Non-unitarity of CKM matrix from the vector singlet quark mixing and neutron electric dipole moment
在标准模型(SM)中,夸克电偶极矩(EDM)的最低阶贡献发生在三圈水平。我们发现,在扩展夸克扇区的模型中,CKM矩阵的非么正性通常会在两个回路水平上产生夸克EDM,除了外部夸克质量外,它没有类似GIM的抑制因子。感生中子EDM的数量级为10^{-29} e cm,如果像SM中发生的那样通过长距离物理进一步增强,则可以很好地在下一代实验的范围内。
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 normali…
In this paper, we consider the low-energy scale inverse seesaw mechanism in which the observed neutrino mass and lepton mixing are explained by introducing right handed neutrinos and the gauge-singlet fermions with experimentally testable energy scale. Moreover, the presence of such new fermions leads to unitarity violation in lepton mixing due to significantly large mixing between active neutrinos and the heavy fermions. In addition to this, such large lepton mixing also gives rise to potentially large lepton flavor violation, which allows to constrain the non-unitarity parameters via lepton …
Impact of matter effects on the unitarity test of lepton mixing
Yukawa Institute for Theoretical Physics, Kyoto University(京都大学汤川理论物理研究所);Department of Physics, Faculty of Engineering Science, Yokohama National University(横滨国立大学工学部物理学系)
A framework for testing leptonic unitarity by neutrino oscillation experiments
如果轻子么正性在远低于电弱标度的能量标度上被新物理破坏,我们称之为低标度么正性破坏,它具有不同于高能标度下么正性破坏的特征。它们包括保持风味普遍性和没有零距离风味过渡。我们提出了一个用中微子振荡实验来检验这种低能么正性破坏的框架。从酉3活性加$N$(任意整数)无菌中微子模型开始,我们表明,通过限制活性无菌和无菌无菌中微子质量平方差为$\gtrsim$ 0.1 eV $^2$的振荡概率在$(3+N)$模型变得不敏感的无菌部门的细节,提供了一个几乎模型独立的框架测试低尺度幺正违反。然而,不育部门的存在留下的痕迹作为一个恒定的概率泄漏项,它区分低尺度的幺正性破坏的高尺度之一。在这两种情况下,活跃中微子子空间中的非幺正混合矩阵是共同的。我们分析了如何严重的么正性违反可以限制在$ν_{e}$行采取JUNO样设置来模拟中等基线反应堆实验。在一阶物质势下讨论了物质效应对$(3+N)$模型特性的可能修正。
We calculate the rates of radiative $β^- \to α^- + γ$ decays for $(α, β) = (e, μ)$, $(e, τ)$ and $(μ, τ)$ by taking the {\it unitary} gauge in the $(3+n)$ active-sterile neutrino mixing scheme, and make it clear that constraints on the unitarity of the $3\times 3$ Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrix $U$ extracted from $β^- \to α^- + γ$ decays in the {\it minimal unitarity violation} scheme differ from those obtained in the canonical seesaw mechanism with $n$ heavy Majorana neutrinos by a factor $5/3$. In such a natural seesaw case we show that the rates of $β^- \to α^- + γ$ can be us…
Testing the unitarity of the light neutrino mixing matrix
University of Trieste(的里雅斯特大学);INFN, Sezione di Trieste(意大利国家核物理研究所的里雅斯特分部);Laboratory of High-Energy and Computational Physics, NICPB(爱沙尼亚核物理与粒子物理研究所高能计算物理实验室);INFN, Laboratori Nazionali di Frascati(意大利国家核物理研究所弗拉斯卡蒂国家实验室);Institute of Computer Science, University of Tartu(塔尔图大学计算机科学研究所)
Unitarity test of lepton mixing via energy dependence of neutrino oscillation
Yukawa Institute for Theoretical Physics, Kyoto University(京都大学汤川理论物理研究所);Department of Physics, Facility of Engineering Science, Yokohama National University(横滨国立大学工学部物理系)
The nearly right unitarity triangle can be simply obtained if a quark mass matrix is written as a linear combination of real rank-1 matrices and the coefficient which gives the mass of the second generation is pure imaginary. Supposing that the source of the CP violation is in the Yukawa coupling to an additional Higgs field which provides a factor for the strange quark and muon mass ratio, we obtain that the angle $α= ϕ_2$ of the unitarity triangle shifts from $90^{\rm o}$ by units of $V_{ub}/V_{us}$, and is postdicted as $α\simeq 87^{\rm o}$ or $91^{\rm o}$. The Dirac CP phase $δ$ which appe…
讨论了$3\times 3$ Cabibbo-Kobayashi-Maskawa(CKM)矩阵的酉三角形和特征可测性.在$3\times 3$ CKM方案之外,我们对Gronau-Wyler-Dunietz方法进行了重定相不变推广,以确定$B^{\pm}_u\rightarrow D K^{\pm}$或$B^0_d\rightarrow D K^{*0}$ vs $\bar{B}^0_d\rightarrow D \bar{K}^{*0}$中的弱相移,这只对$D^0-\bar{D}^0$混合中的潜在新物理敏感。我们还表明,弱角$γ\equiv \arg (-V^*_{ub}V^*_{cd}V_{ud}V_{cb})$是可能的一些$B_d$衰变的$CP$的不对称性确定,即使在一个非标准模型与扩展夸克部门。对$3\times 3$ CKM矩阵的么正性检验作了简要评述。
Deviations from unitarity in the three-neutrino mixing canonical picture are expected in many physics scenarios beyond the Standard Model. The mixing of new heavy neutral leptons with the three light neutrinos would in principle modify the strength and flavour structure of charged-current and neutral-current interactions with matter. Non-unitarity effects would therefore have an impact on the neutrino decoupling processes in the early Universe and on the value of the effective number of neutrinos, $N_{\rm eff}$. We calculate the cosmological energy density in the form of radiation with a non-u…
TeV Scale Inverse Seesaw in SO(10) and Leptonic Non-Unitarity Effects
我们表明,TeV尺度的中微子质量的反跷跷板模型可以实现的框架内的超对称SO(10)模型符合规范耦合统一和观察到的中微子质量和混合。我们提出了我们对轻子混合矩阵中的非么正性效应的期望,其中一些是在未来的中微子工厂中可以观察到的,以及下一代对轻子味道违反过程(如μ-> e + γ)的搜索。该模型具有TeV量级的W_R和Z'玻色子,可以在大型强子对撞机上得到。
Probing unitarity violation of lepton flavor mixing matrix with reactor antineutrinos at JUNO and TAO
Institute of High Energy Physics, Chinese Academy of Sciences(中国科学院高能物理研究所);School of Physical Sciences, University of Chinese Academy of Sciences(中国科学院大学物理科学学院)
Testing the CKM unitarity at high energy via the $W^+W^-$ production at the LHC and future colliders
University of Trieste(的里雅斯特大学);INFN, Sezione di Trieste(意大利国家核物理研究所的里雅斯特分部);Laboratory of High-Energy and Computational Physics, NICPB(爱沙尼亚高等研究院高能计算物理实验室);Institute of Computer Science, University of Tartu(塔尔图大学计算机科学研究所)
Neutrino flavour oscillation is one of the primary indication of the existence of new physics beyond standard model. The presence of small neutrino mass is indispensable to explicate the oscillation among different flavours of neutrino. By the addition of a right handed neutral lepton with the standard model fermions, it is possible to generate tiny neutrino mass. Such additional fermion may induce non-unitarity to the $3\times 3$ PMNS mixing matrix which influences the propagation of neutrino in space-time. In this work the effect of non-unitary mixing matrix is analyzed in neutrino oscillati…
The flavor composition of astrophysical neutrinos observed at neutrino telescopes is related to the initial composition at their sources via oscillation-averaged flavor transitions. If the time evolution of the neutrino flavor states is unitary, the probability of neutrinos changing flavor is solely determined by the unitary mixing matrix that relates the neutrino flavor and propagation eigenstates. In this paper we derive general bounds on the flavor composition of TeV-PeV astrophysical neutrinos based on unitarity constraints. These bounds are useful for studying the flavor composition of hi…