Double Froggatt--Nielsen Mechanism

We present a doubly parametric extension of the standard Froggatt--Nielsen (FN) mechanism. As is well known, mass matrices of the up- and down-type quark sectors and the charged lepton sector in the standard model can be parametrized well by a parameter $\lambda$ which is usually taken to be the sine of the Cabibbo angle ($\lambda = \sin\theta_\text{C} \simeq 0.225$). However, in the neutrino sector, there is still room to realize the two neutrino mass squared differences $\Delta m_\text{sol}^2$ and $\Delta m_\text{atm}^2$, two large mixing angles $\theta _{12}$ and $\theta _{23}$, and non-zero $\theta _{13}$. Then we consider an extension with an additional parameter $\rho$ in addition to $\lambda$. Taking the relevant FN charges for a power of $\lambda~(=0.225)$ and additional FN charges for a power of $\rho$, which we assume to be less than one, we can reproduce the ratio of the two neutrino mass squared differences and three mixing angles. In the normal neutrino mass hierarchy, we show several patterns for taking relevant FN charges and the magnitude of $\rho$. We find that if $\sin \theta_{23}$ is measured more precisely, we can distinguish each pattern. This is testable in the near future, for example in neutrino oscillation experiments. In addition, we predict the Dirac CP-violating phase for each pattern.Comment: 12 pages, 18 figures, final versio

Brane-localized masses in magnetic compactifications

We discuss effects of the brane-localized mass terms on the fixed points of the toroidal orbifold $T^2/Z_2$ under the presence of background magnetic fluxes, where multiple lowest and higher-level Kaluza-Klein (KK) modes are realized before introducing the localized masses in general. Through the knowledge of linear algebra, we find that, in each KK level, one of or more than one of the degenerate KK modes are almost inevitably perturbed, when single or multiple brane-localized mass terms are introduced. When the typical scale of the compactification is far above the electroweak scale or the TeV scale, we apply this mechanism for uplifting unwanted massless or light modes which are prone to appear in models on magnetized orbifolds.Comment: 23 pages, 5 figures, 4 tables, version accepted in PR

CP-violating phase on magnetized toroidal orbifolds

We study the CP-violating phase of the quark sector in the $U(8)$ flavor model on $T^2/Z_N \, (N=2,3,4,6)$ with non-vanishing magnetic fluxes, where properties of possible origins of the CP violation are investigated minutely. In this system, a non-vanishing value is mandatory in the real part of the complex modulus parameter $\tau$ of the two-dimensional torus. On $T^2$ without orbifolding, underlying discrete flavor symmetries severely restrict the form of Yukawa couplings and it is very difficult to reproduce the observed pattern in the quark sector including the CP-violating phase $\delta_{\rm CP}$. In cases of multiple Higgs doublets emerging on $T^2/Z_2$, the mass matrices of the zero-mode fermions can be written in the Gaussian textures by choosing appropriate configurations of vacuum expectation values of the Higgs fields. When such Gaussian textures of mass matrices are realized, we show that all of the quark profiles, which are mass hierarchies among the quarks, quark mixing angles, and $\delta_{\rm CP}$ can be simultaneously realized.Comment: 24 pages, 21 figures, 4 tables (v2, published version from JHEP

Phenomenology of flavorful composite vector bosons in light of BB anomalies

We analyze the flavor structure of composite vector bosons arising in a model of vectorlike technicolor, often called hypercolor (HC), with eight flavors that form a one-family content of HC fermions. Dynamics of the composite vector bosons, referred to as HC rho in this paper, are formulated together with HC pions by the hidden local symmetry (HLS), in a way analogous to QCD vector mesons. Then coupling properties to the standard model (SM) fermions, which respect the HLS gauge symmetry, are described in a way that couplings of the HC rhos to the left-handed SM quarks and leptons are given by a well-defined setup as taking the flavor mixing structures into account. Under the present scenario, we discuss significant bounds on the model from electroweak precision tests, flavor physics, and collider physics. We also try to address B anomalies in processes such as B -> K(*) mu+ mu- and B -> D(*) tau nu, recently reported by LHCb, Belle, (ATLAS, and CMS in part.) Then we find that the present model can account for the anomaly in B -> K(*) mu+ mu- consistently with the other constraints while it predicts no significant deviations in B -> D(*) tau nu from the SM, which can be examined in the future Belle II experiment. The former is archived with the form C9 = -C10 of the Wilson coefficients for effective operators of b -> s mu+ mu-, which has been favored by the recent experimental data. We also investigate current and future experimental limits at the Large Hadron Collider (LHC) and see that possible collider signals come from dijet and ditau, or dimuon resonant searches for the present scenario with TeV mass range. To conclude, the present b -> s mu+ mu- anomaly is likely to imply discovery of new vector bosons in the ditau or dimuon channel in the context of the HC rho model. Our model can be considered as a UV completion of conventional U(1)' model.Comment: 62 pages, 8 figures, 3 tables, typos modified, published versio

ttHttH Anomalous Coupling in Double Higgs Production

We study the effects of top-Higgs anomalous coupling in the production of a pair of Higgs boson via gluon fusion at the Large Hadron Collider (LHC). The introduction of anomalous $ttH$ coupling can alter the hadronic double Higgs boson cross section and can lead to characteristic changes in certain kinematic distributions. We perform a global analysis based on available LHC data on the Higgs to constrain the parameters of $ttH$ anomalous coupling. Possible overlap of the predictions due to anomalous $ttH$ coupling with those due to anomalous trilinear Higgs coupling is also studied. We briefly discuss the effect of the anomalous $ttH$ coupling on the $HZ$ production via gluon fusion which is one of the main backgrounds in the $HH \to \gamma\gamma b {\bar b}$ channel.Comment: 22 pages, 22 figures, 4 tables. Text reorganized, main results unchanged, new plots and references added. Journal versio

Realization of the Lepton Flavor Structure from Point Interactions

We investigate a 5d gauge theory on $S^1$ with point interactions. The point interactions describe extra boundary conditions and provide three generations, the charged lepton mass hierarchy, the lepton flavor mixing and tiny degenerated neutrino masses after choosing suitable boundary conditions and parameters. The existence of the restriction in the flavor mixing, which appears from the configuration of the extra dimension, is one of the features of this model. Tiny Yukawa couplings for the neutrinos also appears without the see-saw mechanism nor symmetries in our model. The magnitude of CP violation in the leptons can be a prediction and is consistent with the current experimental data.Comment: 9 pages, 3 figures, 3rd International Conference on New Frontiers in Physic