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Chao-Shang Huang

Publications and source records attributed to Chao-Shang Huang.

At least 19 recordsLinked to original sources

Comments on "Unified neutrino mixing and approximate $μ-τ$ reflection symmetry" (Mod. Phys. Lett. A, 40 (2025) 26, 2550097 [arXiv:2502.18029 [hep-ph]])

Resolving mass ordering is an important issue in the neutrino physics. In Ref.\cite{yt} the authors investigate the phenomenology of a unified neutrino mixing framework and reveal that the predicted sum of neutrino masses derived from an approximate $μ-τ$ reflection symmetric flavor neutrino mass matrix based on the unified neutrino mixing with an inverted mass ordering, is excluded from DESI2024 and Supernova Ia luminosity distance data. We note that in Ref.\cite{yt} an error is present in Eq.(20), {\it i.e.}, the expression for $ M_{23}^{μ-τ} $, a similar error also appears in Eq.(26) for $M_{13}^{μ-τ}$. That is, the condition that $M_{ee}$ and $M_{μτ}$ are real is omitted. We impose this condition and analyze its consequences. Using the newest data\cite{azz}, it is obtained that the predicted sm derived from the approximate $μ-τ$ reflection symmetric neutrino mass matrices $M_{23}$ for both NO and IO are allowed. We note also that their conclusion is invalid, as it is based on outdated data.

hep-ph

Majorana CP violating phases

The two Majorana cp-violating phases can not be determined by experiments on neutrino oscillations. It is difficult even not possible almost to measure two Majorana cp-violating phases since they are only sensitive to lepton-number-violating processes. One must take some assumption on the structure of neutrino mass matrix and their flavor mixing mechanism hidden behind in phenomenological models in order to determine Majorana cp-violating phases. Two models on the symmetry of the neutrino mass matrix are proposed in this paper. The Majorana cp-violating phases and the effective Majorana neutrino mass $\mathcal{m}_{\mathcal{ee}}$ are computed in the two models. Using the limit of the absolute neutrino mass scale which is from cosmological observations, the numerical values of the Majorana cp-violating phases and the effective Majorana neutrino mass $\mathcal{m}_{\mathcal{ee}}$ are obtained.

hep-ph

Investigation of a kind of neutrino mass matrix

We carry out diagonalization of a kind of Majorana neutrino mass matrix $M=M_νM_ν^\dagger$ of which Real part and Imaginary part are commutative. For the kind of matrix M, it is shown in a model-independent way that $δ= \pmπ/2$ which implies the maximal strength of CP violation in neutrino oscillations and atmospherical mixing angle would be in the ranges, $π/4 < θ_{23} < 3π/4$, or $-3π/4<θ_{23} < - π/4$. It is shown that the kind of Hermitian Majorana neutrino mass matrix M has only five real parameters and furthermore, only one free real parameter (A or D) if using the measured values of three mixing angles and mass squared differences as inputs.

hep-ph

E6 GUT through Effects of Dimension-5 Operators

In the effective field theory framework, quantum gravity can induce effective dimension-5 operators, which have important impacts on grand unified theories. Interestingly, one of main effects is the modification of the usual gauge coupling unification condition. We investigate the gauge coupling unification in $E_{6}$ under modified gauge coupling unification condition at scales $M_X$ in the presence of one or more dimension-5 operators. It is shown that nonsupersymmetric models of $E_6$ unification can be obtained and can easily satisfy the constraints from the proton lifetime. For constructing these models, we consider several maximal subgroups $H=SO(10)\times U(1), H=SU(3)\times SU(3)\times SU(3)$, and $H=SU(2)\times SU(6)$ of $E_{6}$ and the usual breaking chains for a specific maximal subgroup, and derive all of the Clebsch-Gordan coefficients $Φ^{(r)}_{s,z}$ associated with $E_6$ breaking to the Standard Model, which are given in Appendix A.

hep-ph

Six Higgs Doublets Model for Dark Matter

We consider an extension of the Higgs sector in the standard model (SM) with six Higgs doublets. The gauge couplings are unified without supersymmetry in this model. The lightest of the extra Higgs particles, being stabilized by a discrete symmetry imposed from the outset, presents a plausible candidate for dark matter. For a specific acceptable benchmark point, we show that the model is viable regarding the constraints of relic density, direct detection and invisible Higgs decay. We comment on the mean free path of the dark matter candidate.

hep-ph

Distinguishing the right-handed up/charm quarks from top quark via discrete symmetries in the standard model extensions

We propose a class of the two Higgs doublet Standard models (SMs) with a SM singlet and a class of supersymmetric SMs with two pairs of Higgs doublets, where the right-handed up/charm quarks and the right-handed top quark have different quantum numbers under extra discrete symmetries. Thus, the right-handed up and charm quarks couple to one Higgs doublet field, while the right-handed top quark couples to another Higgs doublet. The quark CKM mixings can be generated from the down-type quark sector. As one of phenomenological consequences in our models, we explore whether one can accommodate the observed direct CP asymmetry difference in singly Cabibbo-suppressed D decays. We show that it is possible to explain the measured values of CP violation under relevant experimental constraints.

hep-ph

Effects of Dimension-5 Operators in $E_6$ Grand Unified Theories

The effective dimension-5 operators can be induced by quantum gravity or inspired by string and M theories. They have important impacts on grand unified theories. We investigate the group theoretic nature of them for the well known E(6) model. Considering the breaking chains $E_{6}\mapsto H=SO(10)\times U_{V'}(1)\mapsto SU(5)\times U_{V}(1)\times U_{V'}(1)\mapsto SU(3)\times SU(2)\times U_{Z}(1)\times U_{V}(1)\times U_{V'}(1)$ and $E_{6}\mapsto H=SO(10)\times U_{V'}(1)\mapsto SU(4)\times SU_{L}(2)\times SU_{R}(2)\times U_{V'}(1)\mapsto SU(3)\times SU_{L}(2)\times SU_{R}(2)\times U_{S}(1)\times U_{V'}(1)$, we derive and give all of the Clebsch-Gordan coefficients $Φ^{(r)}_{s,z}$ associated with $E_6$ breaking to the standard model. Some applications of the results are discussed shortly.

hep-ph

Generalization of Friedberg-Lee Symmetry

We study the possible origin of Friedberg-Lee symmetry. First, we propose the generalized Friedberg-Lee symmetry in the potential by including the scalar fields in the field transformations, which can be broken down to the FL symmetry spontaneously. We show that the generalized Friedberg-Lee symmetry allows a typical form of Yukawa couplings, and the realistic neutrino masses and mixings can be generated via see-saw mechanism. If the right-handed neutrinos transform non-trivially under the generalized Friedberg-Lee symmetry, we can have the testable TeV scale see-saw mechanism. Second, we present two models with the $SO(3)\times U(1)$ global flavour symmetry in the lepton sector. After the flavour symmetry breaking, we can obtain the charged lepton masses, and explain the neutrino masses and mixings via see-saw mechanism. Interestingly, the complete neutrino mass matrices are similar to those of the above models with generalized Friedberg-Lee symmetry. So the Friedberg-Lee symmetry is the residual symmetry in the neutrino mass matrix after the $SO(3)\times U(1)$ flavour symmetry breaking.

hep-ph

Direct CP violation of $B \to l ν$ in unparticle physics

We have investigated the effects of unparticles in decays $B \to l ν$. It is found that the direct CP violation in the decays, which is zero in SM, can show up due to the CP conserving phase intrinsic in unparticle physics. For $l=τ$, the direct CP asymmetry can reach 30% for the scalar unparticle contribution, and 100% for the longitudinal vector unparticle contribution under the constraints of ${\rm Br}(B\toτν)$ and $νe$ elastic scattering. If both unparticle-lepton coupling universality and unparticle-quark coupling universality are assumed the constraint from $Br(π\to μν)$ leads that the direct CP violation in $B\to lν$ can only reach at most 8% and 1% for scalar and vector unparticle contributions respectively if $d_{\cal U} < 2$. If the direct CP violation is observed in the future it would give strong evidence for the existence of unparticle stuff.

hep-ph

Search for new physics from $B\toπϕ$

We investigate the pure penguin process $B^-\to π^-ϕ$ using QCD factorization approach to calculate hadronic matrix elements to the $α_s$ order in some well-known NP models. It is shown that the NP contributions in R-parity conserved SUSY models and 2HDMs are not enough to saturate the experimental upper bounds for $B\to ϕπ$. We have shown that the flavor changing $Z^\prime$ models can make the branching ratios of $B\to ϕπ$ to saturate the bound under all relevant experimental constraints.

hep-ph

Embedding Flipped SU(5) into SO(10)

We embed the flipped SU(5) models into the SO(10) models. After the SO(10) gauge symmetry is broken down to the flipped SU(5) \times U(1)_X gauge symmetry, we can split the five/one-plets and ten-plets in the spinor \mathbf{16} and \mathbf{\bar{16}} Higgs fields via the stable sliding singlet mechanism. As in the flipped SU(5) models, these ten-plet Higgs fields can break the flipped SU(5) gauge symmetry down to the Standard Model gauge symmetry. The doublet-triplet splitting problem can be solved naturally by the missing partner mechanism, and the Higgsino-exchange mediated proton decay can be suppressed elegantly. Moreover, we show that there exists one pair of the light Higgs doublets for the electroweak gauge symmetry breaking. Because there exist two pairs of additional vector-like particles with similar intermediate-scale masses, the SU(5) and U(1)_X gauge couplings can be unified at the GUT scale which is reasonably (about one or two orders) higher than the SU(2)_L \times SU(3)_C unification scale. Furthermore, we briefly discuss the simplest SO(10) model with flipped SU(5) embedding, and point out that it can not work without fine-tuning.

hep-ph

Implications for new physics from ${\bar B}^0\to π^0π^0$ and ${\bar B}^0\to {\bar K}^0K^0$

We have analyzed the ${\bar B}^0\to π^0π^0$ puzzle in three kinds of models beyond the standard model (SM). It is shown that the minimal flavor violation (MFV) models, the minimal supersymmetric standard model (MSSM), and the two Higgs doublet models (2HDM) I and II can not give an explanation of the ${\bar B}^0\to π^0π^0$ puzzle within $1 σ$ experimental bounds and the model III 2HDM can explain the puzzle without a conflict with other experimental measurements. If the constraint on $C_{8g}$ from $b\to s g$ is not imposed, for all kinds of insertions considered there are regions of parameter space, where the scalar quark mass is larger (much larger) than the gluino mass in the case of LR or RL (LL or RR), in which the puzzle can be resolved within $1 σ$ experimental bounds.

hep-ph

MSSM Anatomy of the Polarization Puzzle in B --> phi K* Decays

We analyze the $B \to ϕK^{*}$ polarization puzzle in the Minimal Supersymmetric Standard Model (MSSM) including the neutral Higgs boson (NHB) contributions. To calculate the non-factorizable contributions to hadronic matrix elements of operators, we have used the QCD factorization framework to the $α_s $ order. It is shown that the recent experimental results of the polarization fractions in $B\to ϕK^{*}$ decays, which are difficult to be explained in SM, could be explained in MSSM if there are flavor non-diagonal squark mass matrix elements of 2nd and 3rd generations, which also satisfy all relevant constraints from known experiments ($B\to X_sγ, B_s\to μ^+μ^-, B\to X_s μ^+μ^-, B\to X_s g, ΔM_s$, etc.). We have shown in details that the experimental results can be accommodated with the flavor non-diagonal mass insertion of chirality RL, RL+LR, RR, or LL+ RR when the NHB contributions as well as $\mathcal{O}(α_s)$ corrections of hadronic matrix elements of operators are included. However the branching ratios for the decay are smaller than the experimental measurements.

hep-ph

Exclusive Semileptonic Rare Decays $B \to K^{(*)} l^+ l^-$ in a SUSY SO(10) GUT

In the SUSY SO(10) GUT context, we study the exclusive processes $B \to K^{(*)} l^+l^-(l=μ,τ)$. Using the Wilson coefficients of relevant operators including the new operators $Q_{1,2}^{(\prime)}$ which are induced by neutral Higgs boson (NHB) penguins, we evaluate some possible observables associated with these processes like, the invariant mass spectrum (IMS), lepton pair forward backward asymmetry (FBA), lepton polarization asymmetries etc. In this model the contributions from Wilson coefficients $C_{Q_{1,2}}^\prime$, among new contributions, are dominant. Our results show that the NHB effects are sensitive to the FBA, $dL/d\hat{s}$, and $dT/d\hat{s}$ of $B \to K^{(*)} τ^+ τ^-$ decay, which are expected to be measured in B factories, and the average of the normal polarization $dN/d\hat{s}$ can reach several percent for $B \to K μ^+ μ^-$ and it is 0.05 or so for $B\to K τ^+τ^-$, which could be measured in the future super B factories and provide a useful information to probe new physics and discriminate different models.

hep-ph

Supersymmetric SO(10) Models Inspired by Deconstruction

We consider 4-dimensional N=1 supersymmetric SO(10) models inspired by deconstruction of 5-dimensional N=1 supersymmetric orbifold SO(10) models and high dimensional non-supersymmetric SO(10) models with Wilson line gauge symmetry breaking. We discuss the $SO(10) \times SO(10)$ models with bi-fundamental link fields where the gauge symmetry can be broken down to the Pati-Salam, $SU(5) \times U(1)$, flipped $SU(5) \times U(1)'$ or the standard model like gauge symmetry. We also propose an $SO(10) \times SO(6) \times SO(4)$ model with bi-fundamental link fields where the gauge symmetry is broken down to the Pati-Salam gauge symmetry, and an $SO(10) \times SO(10)$ model with bi-spinor link fields where the gauge symmetry is broken down to the flipped $SU(5) \times U(1)'$ gauge symmetry. In these two models, the Pati-Salam and flipped $SU(5) \times U(1)'$ gauge symmetry can be further broken down to the standard model gauge symmetry, the doublet-triplet splittings can be obtained by the missing partner mechanism, and the proton decay problem can be solved. We also study the gauge coupling unification. We briefly comment on the interesting variation models with gauge groups $SO(10) \times SO(6)$ and $SO(10) \times flipped SU(5) \times U(1)'$ in which the proton decay problem can be solved.

hep-ph

CP asymmetry in B \to phi K_S in a SUSY SO(10) GUT

We study the $B\to ϕK_S$ decay in a SUSY SO(10) GUT. We calculate the mass spectrum of sparticles for a given set of parameters at the GUT scale. We complete the calculations of the Wilson coefficients of operators including the new operators which are induced by NHB penguins at LO using the MIA with double insertions. It is shown that the recent experimental results on the time-dependent CP asymmetry $S_{ϕK}$ in $B\to ϕK_S$, which is negative and can not be explained in SM, can be explained in the model where there are flavor non-diagonal right-handed down squark mass matrix elements of 2nd and 3rd generations whose size satisfies all relevant constraints from known experiments ($τ\to μγ$, $B\to X_Sγ, B_s\to μ^+μ^-, B\to X_s μ^+μ^-, B\to X_s g, ΔM_s$, etc.). At the same time, the branching ratio for the decay can also be in agreement with experimental measurements.

hep-ph

B^0_{d,s} - \bar{B}^0_{d,s} mixing in the model III 2HDM

In the model III 2HDM there are new CP violating phases which would affect the $B_{d,s}^0 - \bar{B}_{d,s}^0$ mixing. In this paper, we calculate the new physics contributions to the neutral B meson mass splitting $ΔM_{B_q}$ (q=d, s) at the next-to-leading order (NLO) level. Using the high accuracy data and other relevant data, we draw the constraints on the parameter space of the model III 2HDM. Moreover, we calculate the new physics corrections to the ratio $q/p$. It is found that the phase of $(q/p)_n$ for $B_d$ which is due to the new contributions is very small and consequently in agreement with the measurements of the time dependent CP asymmetry $S_{J/ψK}$ in $B\to J/ψK_S$. On the contrary, the phase of $(q/p)_n$ for $B_s$ is large enough to give significant effects on CP violation in the neutral $B_s$ system.

hep-ph