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Register a new userA Unified Model of Quarks and Leptons with a Universal Texture Zero
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We show that a universal texture zero in the (1,1) position of all fermionic mass matrices, including heavy right-handed Majorana neutrinos driving a type-I see-saw mechanism, can lead to a viable spectrum of mass, mixing and CP violation for both quarks and leptons, including (but not limited to) three important postdictions: the Cabibbo angle, the charged lepton masses, and the leptonic `reactor angle. We model this texture zero with a non-Abelian discrete family symmetry that can easily be embedded in a grand unified framework, and discuss the details of the phenomenology after electroweak and family symmetry breaking. We provide an explicit numerical fit to the available data and obtain excellent agreement with the 18 observables in the charged fermion and neutrino sectors with just 9 free parameters. We further show that the vacua of our new scalar familon fields are readily aligned along desired directions in family space, and also demonstrate discrete gauge anomaly freedom at the relevant scale of our effective theory.
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Multi-spinor fields which behave as triple-tensor products of the Dirac spinors and form reducible representations of the Lorentz group describe three families of ordinary quarks and leptons in the visible sector and an additional family of exotic dark quarks and leptons in the dark sector of the Universe. Apart from the ordinary set of the gauge and Higgs fields in the visible sector, another set of gauge and Higgs fields belonging to the dark sector are assumed to exist. Two sectors possess channels of communication through gravity and a bi-quadratic interaction between the two types of Higgs fields. A candidate for the main component of the dark matter is a stable dark hadron with spin 3/2, and the upper limit of its mass is estimated to be 15.1 GeV/c$^2$.
A generalized inverse seesaw model, in which the 9x9 neutrino mass matrix has vanishing (1,1) and (1,3) submatrices, is proposed. This is similar to the universal two-zero texture which gives vanishing (1,1) and (1,3) elements of the 3x3 mass matrices in both the charged lepton and neutrino sectors. We consider the Z_6 x Z_6 group to realize such texture zeros. We study this generalized inverse seesaw model systematically and derive the seesaw formula for the 3x3 mass matrix of three active neutrinos. We also analyze the universal two-zero texture in the general case and propose two ansatze to reduce the number of free parameters. Taking account of the new result of theta_{13} from the Daya Bay experiment, we constrain the parameter space of the universal two-zero texture in the general case and in the two ansatze, respectively. We find that one of the ansatze works well.
In this paper, we consider a set of new symmetries in the SM, {it diagonal reflection} symmetries $R , m_{u, u}^{*} , R = m_{u, u}, ~ m_{d,e}^{*} = m_{d,e}$ with $R =$ diag $(-1,1,1)$. These generalized $CP$ symmetries predict the Majorana phases to be $alpha_{2,3} /2 sim 0$ or $pi /2$. A realization of reflection symmetries suggests a broken chiral $U(1)_{rm PQ}$ symmetry and a flavored axion. The axion scale is suggested to be $langle theta_{u,d} rangle sim Lambda_{rm GUT} , sqrt{m_{u,d} , m_{c,s}} / v sim 10^{12} , $[GeV]. By combining the symmetries with the four-zero texture, the mass eigenvalues and mixing matrices of quarks and leptons are reproduced well. This scheme predicts the normal hierarchy, the Dirac phase $delta_{CP} simeq 203^{circ},$ and $|m_{1}| simeq 2.5$ or $6.2 , $[meV]. In this scheme, the type-I seesaw mechanism and a given neutrino Yukawa matrix $Y_{ u}$ completely determine the structure of right-handed neutrino mass $M_{R}$. An $u- u$ unification predicts mass eigenvalues to be $ (M_{R1} , , M_{R2} , , M_{R3}) = (O (10^{5}) , , O (10^{9}) , , O (10^{14})) , $[GeV].
In this letter, we consider exact $mu-tau$ reflection symmetries for quarks and leptons. Fermion mass matrices are assumed to be four-zero textures for charged fermions $f = u,d,e$ and a symmetric matrix for neutrinos $ u_{L}$. By a bi-maximal transformation, all the mass matrices lead to $mu-tau$ reflection symmetric forms, which seperately satisfy $T_{u} , m_{u, u}^{*} , T_{u} = m_{u, u}$ and $T_{d} , m_{d,e}^{*} , T_{d} = m_{d,e}$. Reconciliation between the $mu-tau$ reflection symmetries and observed $sin theta_{13}$ predicts $delta_{CP} simeq 203^{circ}$. Moreover, imposition of universal texture $(m_{f})_{11} = 0$ for $f=u,d, u,e$ predicts the normal hierarchy with the lightest neutrino mass $|m_{1}| = 6.26$ or $2.54$ meV.
We discuss a new mass matrix with specific texture zeros for the quarks. The three flavor mixing angles for the quarks are functions of the quark masses and can be calculated. The following ratios among CKM matrix elements are given by ratios of quark masses: |Vtd/Vts| q md /ms and |Vub/Vcb| p mu/mc . Also we can calculate two CKM matrix elements: |Vcb| |Vts| 2 (ms/mb ). This relation as well as the relation |Vtd/Vts| q md /ms are in good agreement with the experimental data. There is a problem with the relation |Vub/Vcb| p mu/mc , probably due to wrong estimates of the quark masses mu and m
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