Flavor structures of charged fermions and massive neutrinos

Zhang, Xing

doi:10.1016/j.physrep.2020.02.001

Cited by 207 publications

(206 citation statements)

References 919 publications

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“…(14) and (15) keep unchanged with the replacements ρ → ρ and η → η, vertex ( ρ, η) must be located on the same circular arc. This observation geometrically illustrates how similar c and s are, and it can be extended to similar discussions about the other two pairs of the CKM unitarity triangles, whose shapes are nevertheless very sharp [7].…”

Section: The Vertices Of S and C On A Circular Arcsupporting

confidence: 67%

“…The analytical approximations made in Eqs. (6) and (7) allow us to see some fine differences between the vertices (ρ, η) and ( ρ, η) of these two triangles as follows:…”

Section: The Vertices Of S and C On A Circular Arcmentioning

confidence: 99%

“…As a result, ρ 0.134 and η 0.368 can be obtained from Eq. (7). The differences ρ − ρ 0.012 and η − η 0.013 mean that the twin triangles c and s will be experimentally distinguishable if their vertices (ρ, η) and ( ρ, η) can be determined at the 1% precision level.…”

Section: The Vertices Of S and C On A Circular Arcmentioning

confidence: 99%

“…When Λ is far above the electroweak scale Λ EW ∼ 10 2 GeV, the RGE running effects of V will become appreciable and should be taken into account (see Ref. [7] for a recent review). In particular, the two-loop RGEs of V have been derived for Λ evolving between Λ EW and Λ GUT ∼ 10 16 GeV in the framework of the SM or its minimal supersymmetric version (MSSM) [10,11,12,13].…”

Section: Two-loop Rge Evolution Of S and Cmentioning

confidence: 99%

“…where each triangle is named after the flavor index that does not appear in its three sides [6,7]. The reason is simply that these two triangles are almost congruent with each other, and hence their differences in sides and inner angles are experimentally indistinguishable at present.…”

Section: Introductionmentioning

confidence: 99%

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Distinguishing between the twin b-flavored unitarity triangles on a circular arc

Zhang

2020

Physics Letters B

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With the help of the generalized Wolfenstein parametrization of quark flavor mixing and CP violation, we calculate fine differences between the twin b-flavored unitarity triangles defined by V * ub V ud +V * cb V cd +V * tb V td = 0 and V * ud V td +V * us V ts +V * ub V tb = 0 in the complex plane. We find that vertices of the rescaled versions of these two triangles, described respectively, are located on a circular arc whose center and radius are given by O = (0.5, 0.5 cot α) and R = 0.5 csc α with α being their common inner angle. The small difference between (ρ, η) and ( ρ, η) is characterized by ρ − ρ ∼ η − η ∼ O(λ 2 ) with λ 0.22 being the Wolfenstein expansion parameter, and these two vertices are insensitive to the two-loop renormalization-group running effects up to the accuracy of O(λ 4 ). Some comments are also made on similar features of three pairs of the rescaled unitarity triangles of lepton flavor mixing and CP violation. *

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Section: The Vertices Of S and C On A Circular Arcsupporting

confidence: 67%

“…The analytical approximations made in Eqs. (6) and (7) allow us to see some fine differences between the vertices (ρ, η) and ( ρ, η) of these two triangles as follows:…”

Section: The Vertices Of S and C On A Circular Arcmentioning

confidence: 99%

Section: The Vertices Of S and C On A Circular Arcmentioning

confidence: 99%

Section: Two-loop Rge Evolution Of S and Cmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Distinguishing between the twin b-flavored unitarity triangles on a circular arc

Zhang

2020

Physics Letters B

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Power-aligned 2HDM: a correlative perspective on (g − 2)e,μ

et al. 2021

J. High Energ. Phys.

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With the hypothesis of minimal flavor violation, we find that there exists a power-aligned relation between the Yukawa couplings of the two scalar doublets in the two-Higgs-doublet model with Hermitian Yukawa matrices. Within such a power-aligned framework, it is found that a simultaneous explanation of the anomalies observed in the electron and muon anomalous magnetic moments can be reached with TeV-scale quasi-degenerate Higgs masses, and the resulting parameter space is also phenomenologically safer under the B-physics, Z and τ decay data, as well as the current LHC bounds. Furthermore, the flavor-universal power that enhances the charged-lepton Yukawa couplings prompts an interesting correlation between the two anomalies, which makes the model distinguishable from the (generalized) linearly aligned and the lepton-specific two-Higgs-doublet models that address the same anomalies but in a non-correlative manner, and hence testable by future precise measurements.

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CP asymmetry in the angular distributions of τ → KSπντ decays. Part II. General effective field theory analysis

Chen

Peng

et al. 2022

J. High Energ. Phys.

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In this work, we proceed to study the CP asymmetry in the angular distributions of τ → KSπντ decays within a general effective field theory framework including four-fermion operators up to dimension-six. It is found that, besides the commonly considered scalar-vector interference, the tensor-scalar interference can also produce a non-zero CP asymmetry in the angular distributions, in the presence of complex couplings. Using the dispersive representations of the Kπ form factors as inputs, and taking into account the detector efficiencies of the Belle measurement, we firstly update our previous SM predictions for the CP asymmetries in the same four Kπ invariant-mass bins as set by the Belle collaboration. Bounds on the effective couplings of the non-standard scalar and tensor interactions are then obtained under the combined constraints from the CP asymmetries measured in the four bins and the branching ratio of τ−→ KSπ−ντ decay, with the numerical results given respectively by $$ \operatorname{Im}\left[{\hat{\upepsilon}}_S\right] $$ Im ϵ ̂ S = −0.008 ± 0.027 and $$ \operatorname{Im}\left[{\hat{\upepsilon}}_T\right] $$ Im ϵ ̂ T = 0.03 ± 0.12, at the renormalization scale μτ = 2 GeV in the $$ \overline{\mathrm{MS}} $$ MS ¯ scheme. Using the best-fit values, we also find that the distributions of the CP asymmetries can deviate significantly from the SM expectation in almost the whole Kπ invariant-mass region. Nevertheless, the current bounds on $$ \operatorname{Im}\left[{\hat{\upepsilon}}_S\right] $$ Im ϵ ̂ S and $$ \operatorname{Im}\left[{\hat{\upepsilon}}_T\right] $$ Im ϵ ̂ T are still plagued by large experimental uncertainties, but will be improved with more precise measurements from the Belle II experiment as well as the proposed Tera-Z and STCF facilities. Assuming further that the non-standard scalar and tensor interactions originate from a weakly-coupled heavy new physics well above the electroweak scale, the SU(2)L invariance of the resulting SMEFT Lagrangian would indicate that very strong limits on $$ \operatorname{Im}\left[{\hat{\upepsilon}}_S\right] $$ Im ϵ ̂ S and $$ \operatorname{Im}\left[{\hat{\upepsilon}}_T\right] $$ Im ϵ ̂ T could also be obtained from the neutron electric dipole moment and the $$ {D}^0-{\overline{D}}^0 $$ D 0 − D ¯ 0 mixing. With the bounds from these processes taken into account, it is then found that, unless there exist extraordinary cancellations between the new physics contributions, neither the scalar nor the tensor interaction can produce any significant effects on the CP asymmetries (relative to the SM predictions) in the processes considered, especially under the “single coefficient dominance” assumption.

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Flavor structures of charged fermions and massive neutrinos

Cited by 207 publications

References 919 publications

Distinguishing between the twin b-flavored unitarity triangles on a circular arc

Distinguishing between the twin b-flavored unitarity triangles on a circular arc

Power-aligned 2HDM: a correlative perspective on (g − 2)e,μ

CP asymmetry in the angular distributions of τ → KSπντ decays. Part II. General effective field theory analysis

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