arXiv subjects

Gui-Jun Ding

Publications and source records attributed to Gui-Jun Ding.

At least 109 records · Page 6Linked to original sources

arXiv2014

Generalised CP and Trimaximal TM$_1$ Lepton Mixing in $S_4$ Family Symmetry

We construct two flavor models based on $S_4$ family symmetry and generalised CP symmetry. In both models, the $S_4$ family symmetry is broken down to the $Z^{SU}_2$ subgroup in the neutrino sector, as a consequence, the trimaximal $\text{TM}_1$ lepton mixing is produced. Depending on the free parameters in the flavon potential, the Dirac CP is predicted to be either conserved or maximally broken, and the Majorana CP phases are trivial. The two models differ in the neutrino sector. The flavon fields are involved in the Dirac mass terms at leading order in the first model, and the neutrino mass matrix contains three real parameters such that the absolute neutrino masses are fixed. Nevertheless, the flavon fields enter into the Majorana mass terms at leading order in the second model. The leading order lepton mixing is of the tri-bimaximal form which is broken down to $\text{TM}_1$ by the next to leading order contributions.

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arXiv2013

Dirac Neutrinos with $S_4$ Flavor Symmetry in Warped Extra Dimensions

We present a warped extra dimension model with the custodial symmetry $SU(2)_L\times SU(2)_R\times U(1)_X\times P_{LR}$ based on the flavor symmetry $S_4\times Z_2\times Z'_2$, and the neutrinos are taken to be Dirac particles. At leading order, the democratic lepton mixing is derived exactly, and the high dimensional operators introduce corrections of order $λ_c$ to all the three lepton mixing angles such that agreement with the experimental data can be achieved. The neutrino mass spectrum is predicted to be of the inverted hierarchy and the second octant of $θ_{23}$ is preferred. We suggest the modified democratic mixing, which is obtained by permuting the second and the third rows of the democratic mixing matrix, should be a good first order approximation to understanding sizable $θ_{13}$ and the first octant of $θ_{23}$. The constraints on the model from the electroweak precision measurements are discussed. Furthermore, we investigate the lepton mixing patterns for all the possible residual symmetries $G_ν$ and $G_{l}$ in the neutrino and charged lepton sectors, respectively.

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arXiv2013

Bilarge Neutrino Mixing and Abelian Flavor Symmetry

We explore two bilarge neutrino mixing anz$\ddot{a}$tze within the context of Abelian flavor symmetry theories: ($\mathrm{\tt BL_1}$) $\sinθ_{12}\simλ$, $\sinθ_{13}\simλ$, $\sinθ_{23}\simλ$, and ($\mathrm{\tt BL_2}$) $\sinθ_{12}\simλ$, $\sinθ_{13}\simλ$, $\sinθ_{23}\sim 1-λ$. The first pattern is proposed by two of us and is favored if the atmospheric mixing angle $θ_{23}$ lies in the first octant, while the second one is preferred for the second octant of $θ_{23}$. In order to reproduce the second texture, we find that the flavor symmetry should be $U(1)\times Z_m$, while for the first pattern the flavor symmetry should be extended to $U(1)\times Z_m\times Z_n$ with $m$ and $n$ of different parity. Explicit models for both mixing patterns are constructed based on the flavor symmetries $U(1)\times Z_3\times Z_4$ and $U(1)\times Z_2$. The models are extended to the quark sector within the framework of SU(5) grand unified theory in order to give a successful description of quark and lepton masses and mixing simultaneously. Phenomenological implications are discussed.

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arXiv2012

TFH Mixing Patterns, Large $θ_{13}$ and $Δ(96)$ Flavor Symmetry

We perform a comprehensive analysis of the Toorop-Feruglio-Hagedorn (TFH) mixing patterns within the family symmetry $Δ(96)$. The general neutrino mass matrix for the TFH mixing and its symmetry properties are investigated. The possible realizations of the TFH mixing in $Δ(96)$ are analyzed in the minimalist approach. We propose two dynamical models which produce the TFH mixing patterns at leading order. The full flavor symmetries are $Δ(96)\times Z_3\times Z_3$ and $Δ(96)\times Z_5 \times Z_2$ respectively. The next to leading order terms introduce corrections of order $λ^2_c$ to the three mixing angles in both models. The allowed mixing patterns are studied under the condition that the Klein four subgroups and the cyclic $Z_N$ subgroups with $N\geq3$ are preserved in the neutrino and the charged lepton sector respectively. We suggest that the deformed tri-bimaximal mixing is a good leading order approximation to understanding a largish reactor angle.

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arXiv2012

Bottomonium Spectrum with Coupled-Channel Effects

We study the bottomonium spectrum in the nonrelativistic quark model with the coupled-channel effects. The mass shifts and valence $b\bar{b}$ component are evaluated to be rather large. We find that the hadronic loop effects can be partially absorbed into a reselection of the model parameters. No bottomonium state except $Υ(5\,^1S_0)$ and $Υ(5\,^3S_1)$ with mass around 10890 MeV is found in the quark models both with and without coupled-channel effects, so we suggest that $Y_{b}(10890)$ is an exotic state beyond the quark model, if it is confirmed to be a new resonance. The predictions for the $χ_b(3P)$ masses are consistent with the ATLAS measurements. If some new bottomonium-like states are observed at LHCb or SuperB in the future, we can determine whether they are conventional bottomonium or exotic states by comparing their masses with the mass spectrum predicted in our work.

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arXiv2012

Proceedings of the first workshop on Flavor Symmetries and consequences in Accelerators and Cosmology (FLASY2011)

The main goals of the first "Workshop on FLAvor SYmmetries and consequences in accelerators and cosmology" (FLASY) was to summarize the theoretical status of flavor symmetries, bringing together young researchers in the field to stimulate discussions and new collaborations, with the aim of investigating possible new physics scenarios to be tested at the LHC, as well as in future neutrino, cosmology experiments and dark matter searches.

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arXiv2012

Golden Ratio Neutrino Mixing and $A_5$ Flavor Symmetry

We provide a systematic and thorough exploration of lepton flavor models in which the solar mixing angle is related to the golden ratio. For scenarios in which the solar mixing angle is given by the inverse cotangent of the golden ratio, we demonstrate that $A_5$ is the smallest non-Abelian finite group that contains all of the symmetries necessary to enforce this specific lepton mixing pattern. Within this context, we propose two lepton flavor models that yield this mixing pattern through the breaking of $A_5$ at leading order to the Klein four subgroup in the neutrino sector. Both models have triplet embeddings of the lepton doublets as well as the charged lepton singlets. In the charged lepton sector, the residual symmetry is $Z_5$ in the first model, while in the second model, $A_5$ is broken completely at leading order. For the second model, the reactor mixing angle vanishes at leading order and is of the order of the square of the Cabibbo angle at next-to-leading order, which is allowed by the global analysis of current lepton data.

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arXiv2011

A Model for Tri-bimaximal Mixing from a Completely Broken $A_4$

We propose a new $A_4$ model in which both the right-handed neutrinos and right-handed charged leptons transform as $A_4$ singlets. We reproduce tri-bimaximal mixing pattern exactly although the $A_4$ symmetry is broken completely at leading order in both the neutrino and charged lepton sectors. The charged lepton mass hierarchies are controlled by the spontaneous breaking of the flavor symmetry. The light neutrino spectrum is predicted to be of normal type and the lightest neutrino is massless at leading order. Although the reactor angle $θ_{13}$ is expected to be of order $λ^2_c$ from the next to leading order corrections, this model cannot be ruled out by current experimental data including the latest T2K results. Leptogenesis is realized via the resonant leptogenesis of the second and the third heavy right-handed neutrinos which are degenerate at leading order. The phenomenological consequences for lepton flavor violation are discussed in detail.

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arXiv2011

Tri-Bimaximal Neutrino Mixing and the $T_{13}$ Flavor Symmetry

We present a supersymmetric $T_{13}$ model for the tri-bimaximal neutrino mixing, and the complete flavor group is $T_{13}\times Z_{4}\times Z_2$. At leading order, the residual symmetry of the charged lepton sector is $Z_3$, and the $T_{13}$ symmetry is broken completely in the neutrino sector. The charged lepton mass hierarchies are determined by the spontaneous breaking of the flavor symmetry, both the type I see-saw mechanism and the Weinberg operator contribute to generating the light neutrino masses. Tri-bimaximal mixing is exact at leading order while subleading contributions introduce corrections of order $λ^2_c$ to the three lepton mixing angles. The vacuum alignment and subleading corrections are studied in detail, a moderate hierarchy of order $λ_c$ between the vacuum expectation values of the flavon fields in the charged lepton and neutrino sectors can be accommodated.

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arXiv2011

Renormalization Group Running of Lepton Mixing Parameters in See-Saw Models with $S_4$ Flavor Symmetry

We study the renormalization group running of the tri-bimaximal mixing predicted by the two typical $S_4$ flavor models at leading order. Although the textures of the mass matrices are completely different, the evolution of neutrino mass and mixing parameters is found to display approximately the same pattern. For both normal hierarchy and inverted hierarchy spectrum, the quantum corrections to both atmospheric and reactor neutrino mixing angles are so small that they can be neglected. The evolution of the solar mixing angle $θ_{12}$ depends on $\tanβ$ and neutrino mass spectrum, the deviation from its tri-bimaximal value could be large. Taking into account the renormalization group running effect, the neutrino spectrum is constrained by experimental data on $θ_{12}$ in addition to the self-consistency conditions of the models, and the inverted hierarchy spectrum is disfavored for large $\tanβ$. The evolution of light-neutrino masses is approximately described by a common scaling factor.

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arXiv2011

Discovery in Drell-Yan Processes at the LHC

We study the Drell-Yan process mediated by a new bosonic resonance at the LHC. The bosons of spin-0, 1, and 2 with the most general leading-order couplings to Standard Model fermions and gluons are considered, which provide a model-independent formulation for future exploration of the resonance properties, such as its spin, mass and couplings. In the case of neutral resonances, we demonstrate how the shapes of the kinematical distributions change as one varies the chiral couplings of the quarks and leptons, and show how to analyze the couplings by making use of the forward-backward asymmetry. In the case of charged resonances, we propose a novel technique to effectively reconstruct the angular distribution in the center-of-mass frame, to a large extent avoiding the two-fold ambiguity due to the missing neutrino. Similar to the case of a neutral resonance, the spin information of the resonance can be extracted unambiguously, and chiral couplings and the asymmetries can be explored in a statistical manner. With the current LHC data, we present bounds on the mass and cross section times branching fraction of the new resonance and estimate the future reach.

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arXiv2011

Adjoint SUSY $SU(5)$ Grand Unified Model with $S_4$ Flavor Symmetry

We construct a supersymmetric (SUSY) $SU(5)$ model with the flavor symmetry $S_4\times Z_3\times Z_4$. Three generations of adjoint matter fields are introduced to generate the neutrino masses via the combined type I and type III see-saw mechanism. The first two generations of the the $\mathbf{10}$ dimensional representation in $SU(5)$ are assigned to be a doublet of $S_4$, the second family $\mathbf{10}$ is chose as the first component of the doublet, and the first family as the second component. Tri-bimaximal mixing in the neutrino sector is predicted exactly at leading order, charged lepton mixing leads to small deviation from the tri-bimaximal mixing pattern. Subleading contributions introduce corrections of order $λ^2_c$ to all three lepton mixing angles. The model also reproduces a realistic pattern of quark and charged lepton masses and quark mixings. The phenomenological implications of the model are analyzed in datail.

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arXiv2010

$X(1835)$ and the New Resonances $X(2120)$ and $X(2370)$ Observed by the BES Collaboration

We calculate the decay widths of both the second and the third radial excitations of $η$ and $η'$ within the framework of $^3P_0$ model. After comparing the theoretical decay widths and decay patterns with the available experimental data of $η(1760)$, $X(1835)$, $X(2120)$ and $X(2370)$, we find that the interpretation of $η(1760)$ and $X(1835)$ as the second radial excitation of $η$ and $η'$ crucially depends on the measured mass and width of $η(1760)$, which is still controversial experimentally. We suggest that there may be sizable $p\bar{p}$ content in $X(1835)$. $X(2120)$ and $X(2370)$ can not be understood as the third radial excitations of $η$ and $η'$, $X(2370)$ probably is a mixture of $η'(4{^1}{S}{_0})$ and glueball.

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arXiv2009

Lepton Flavor Violation in Models with $A_4$ and $S_4$ Flavor Symmetries

The lepton flavor violation $μ\to eγ$, $τ\to eγ$, $τ\toμγ$, $μ\to3e$, $τ\to3e$, $τ\to3μ$ and $μ-e$ conversion in Al and Ti are studied in both the Altarelli-Feruglio $A_4$ model and the $S_4$ model of Ding. The rates of these lepton flavor violation process for the inverted hierarchy neutrino mass spectrum are enhanced considerably by the next to leading order contributions. For both models, we find that the $μ-e$ conversion in Ti is within the precision of next generation experiments in all the parameter space considered, the $μ-e$ conversion in Al should be observable at least in a very significant part of the parameter space, whereas $τ\to eγ$, $τ\toμγ$, $τ\to3e$ and $τ\to3μ$ are below the expected future sensitivity. The detectability of $μ\to eγ$ and $μ\to3e$ in near future depends on the models and the neutrino mass spectrum. We suggest that a comprehensive consideration of the lepton flavor violation processes is important to test and distinguish both discrete flavor symmetry models.

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arXiv2009

Fermion Masses and Flavor Mixings in a Model with $S_4$ Flavor Symmetry

We present a supersymmetric model of quark and lepton based on $S_4\times Z_3\times Z_4$ flavor symmetry. The $S_4$ symmetry is broken down to Klein four and $Z_3$ subgroups in the neutrino and the charged lepton sectors respectively. Tri-Bimaximal mixing and the charged lepton mass hierarchies are reproduced simultaneously at leading order. Moreover, a realistic pattern of quark masses and mixing angles is generated with the exception of the mixing angle between the first two generations, which requires a small accidental enhancement. It is remarkable that the mass hierarchies are controlled by the spontaneous breaking of flavor symmetry in our model. The next to leading order contributions are studied, all the fermion masses and mixing angles receive corrections of relative order $λ^2_c$ with respect to the leading order results. The phenomenological consequences of the model are analyzed, the neutrino mass spectrum can be normal hierarchy or inverted hierarchy, and the combined measurement of the $0\nu2β$ decay effective mass $m_{ββ}$ and the lightest neutrino mass can distinguish the normal hierarchy from the inverted hierarchy.

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arXiv2009

Bound States of the Heavy Flavor Vector Mesons and Y(4008) and $Z^{+}_1(4050)$

The $D^{*}\bar{D}^{*}$ and $B^{*}\bar{B}^{*}$ systems are studied dynamically in the one boson exchange model, where $π$, $η$, $σ$, $ρ$ and $ω$ exchanges are taken into account. Ten allowed states with low spin parity are considered. We suggest that the $1^{--}$, $2^{++}$, $0^{++}$ and $0^{-+}$ $B^{*}\bar{B}^{*}$ molecules should exist, and the $D^{*}\bar{D}^{*}$ bound states with the same quantum numbers very likely exist as well. However, the CP exotic ($1^{-+}$, $2^{+-}$) $B^{*}\bar{B}^{*}$ and $D^{*}\bar{D}^{*}$ states may not be bound by the one boson exchange potential. We find that the I=0 configuration is more deeply bound than the I=1 configuration, hence $Z^{+}_1(4050)$ may not be a $D^{*}\bar{D}^{*}$ molecule. Although Y(4008) is close to the $D^{*}\bar{D}^{*}$ threshold, the interpretation of Y(4008) as a $D^{*}\bar{D}^{*}$ molecule is not favored by its huge width. $1^{--}$ $D^{*}\bar{D}^{*}$ and $B^{*}\bar{B}^{*}$ states can be produced copiously in $e^{+}e^{-}$ annihilation, detailed scanning of the $e^{+}e^{-}$ annihilation data near the $D^{*}\bar{D}^{*}$ and $B^{*}\bar{B}^{*}$ threshold is an important check to our predictions.

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arXiv2009

Possible Molecular States of $D^{}_s\bar{D}^{}_s$ System and Y(4140)

The interpretation of Y(4140) as a $D^{*}_s\bar{D}^{*}_s$ molecule is studied dynamically in the one boson exchange approach, where $σ$, $η$ and $ϕ$ exchange are included. Ten allowed $D^{*}_s\bar{D}^{*}_s$ states with low spin parity are considered, we find that the $J^{PC}=0^{++}$, $1^{+-}$, $0^{-+}$, $2^{++}$ and $1^{--}$ $D^{*}_s\bar{D}^{*}_s$ configurations are most tightly bound. We suggest the most favorable quantum numbers are $J^{PC}=0^{++}$ for Y(4140) as a $D^{*}_s\bar{D}^{*}_s$ molecule, however, $J^{PC}=0^{-+}$ and $2^{++}$ can not be excluded. We propose to search for the $1^{+-}$ and $1^{--}$ partners in the $J/ψη$ and $J/ψη'$ final states, which is an important test of the molecular hypothesis of Y(4140) and the reasonability of our model. The $0^{++}$ $B^{*}_s\bar{B}^{*}_s$ molecule is deeply bound, experimental search in the $Υ(1S)ϕ$ channel at Tevatron and LHC is suggested.

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arXiv2009

Dynamics of Hadronic Molecule in One-Boson Exchange Approach and Possible Heavy Flavor Molecules

We extend the one pion exchange model at quark level to include the short distance contributions coming from $η$, $σ$, $ρ$ and $ω$ exchange. This formalism is applied to discuss the possible molecular states of $D\bar{D}^{*}/\bar{D}D^{*}$, $B\bar{B}^{*}/\bar{B}B^{*}$, $DD^{*}$, $BB^{*}$, the pseudoscalar-vector systems with $C=B=1$ and $C=-B=1$ respectively. The "$δ$ function" term contribution and the S-D mixing effects have been taken into account. We find the conclusions reached after including the heavier mesons exchange are qualitatively the same as those in the one pion exchange model. The previous suggestion that $1^{++}$ $B\bar{B}^{*}/\bar{B}B^{*}$ molecule should exist, is confirmed in the one boson exchange model, whereas $DD^{*}$ bound state should not exist. The $D\bar{D}^{*}/\bar{D}D^{*}$ system can accomodate a $1^{++}$ molecule close to the threshold, the mixing between the molecule and the conventional charmonium has to be considered to identify this state with X(3872). For the $BB^{*}$ system, the pseudoscalar-vector systems with $C=B=1$ and $C=-B=1$, near threshold molecular states may exist. These bound states should be rather narrow, isospin is violated and the I=0 component is dominant. Experimental search channels for these states are suggested.

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