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Register a new userMixing of 1/2^- Octets under SU(3) Symmetry
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We investigate the J^p=1/2^- baryons in the octets based on flavor SU(3) symmetry. Since baryons with same quantum numbers can mix with each other, we consider the mixing between two octets before their mixing with the singlet. Most predicted decay widths are consistent with the experimental data, and meanwhile we predict two possible $Xi$ mass ranges of the two octets.
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We investigate the consequences of $mu-tau$ reflection symmetry in presence of a light sterile neutrino for the $3+1$ neutrino mixing scheme. We discuss the implications of total $mu-tau$ reflection symmetry as well partial $mu-tau$ reflection symmetry. For the total $mu-tau$ reflection symmetry we find values of $theta_{23}$ and $delta$ remains confined near $pi/4$ and $pm pi/2$ respectively. The current allowed region for $theta_{23}$ and $delta$ in case of inverted hierarchy lies outside the area preferred by the total $mu-tau$ reflection symmetry. However, interesting predictions on the neutrino mixing angles and Dirac CP violating phases are obtained considering partial $mu-tau$ reflection symmetry. We obtain predictive correlations between the neutrino mixing angle $theta_{23}$ and Dirac CP phase $delta$ and study the testability of these correlations at the future long baseline experiment DUNE. We find that while the imposition of $mu-tau$ reflection symmetry in the first column admit both normal and inverted neutrino mass hierarchy, demanding $mu-tau$ reflection symmetry for the second column excludes the inverted hierarchy. Interestingly, the sterile mixing angle $theta_{34}$ gets tightly constrained considering the $mu-tau$ reflection symmetry in the fourth column. We also study consequences of $mu-tau$ reflection symmetry for the Majorana phases and neutrinoless double beta decay.
We study the left-right asymmetric model based on SU(3)_C otimes SU(2)_L otimes SU(3)_R otimes U(1)_X gauge group, which improves the theoretical and phenomenological aspects of the known left-right symmetric model. This new gauge symmetry yields that the fermion generation number is three, and the tree-level flavor-changing neutral currents arise in both gauge and scalar sectors. Also, it can provide the observed neutrino masses as well as dark matter automatically. Further, we investigate the mass spectrum of the gauge and scalar fields. All the gauge interactions of the fermions and scalars are derived. We examine the tree-level contributions of the new neutral vector, Z_R, and new neutral scalar, H_2, to flavor-violating neutral meson mixings, say K-bar{K}, B_d-bar{B}_d, and B_s-bar{B}_s, which strongly constrain the new physics scale as well as the elements of the right-handed quark mixing matrices. The bounds for the new physics scale are in agreement with those coming from the rho-parameter as well as the mixing parameters between W, Z bosons and new gauge bosons.
An extra $SU(2)_D$ gauge factor is added to the well-known left-right extension of the standard model (SM) of quarks and leptons. Under $SU(2)_L times SU(2)_R times SU(2)_D$, two fermion bidoublets $(2,1,2)$ and $(1,2,2)$ are assumed. The resulting model has an automatic dark $U(1)$ symmetry, in the same way that the SM has automatic baryon and lepton $U(1)$ symmetries. Phenomenological implications are discussed, as well as the possible origin of this proposal.
Flavor mixing is scrutinized at 1-loop in a SU(2)_L gauge theory of massive fermions. The main issue is to cope with kinetic-like, momentum (p^2) dependent effective interactions that arise at this order. They spoil the unitarity of the connection between flavor and mass states, which potentially alters the standard Cabibbo-Kobayashi-Maskawa (CKM) phenomenology by giving rise, in particular, to extra flavor changing neutral currents (FCNC). We explore the conservative requirement that these should be suppressed, which yields relations between the CKM angles, the fermion and $W$ masses, and a renormalization scale $mu$. For two generations, two solutions arise: either the mixing angle of the fermion pair the closer to degeneracy is close to maximal while, inversely, the mass and flavor states of the other pair are quasi-aligned, or mixing angles in both sectors are very small. For three generations, all mixing angles of neutrinos are predicted to be large (theta_{23}, close to maximal, is the largest) and the smallness of their mass differences induces mass-flavor quasi-alignment for all charged leptons. The hadronic sector differs in that the top quark is twice as heavy as the W. The situation is, there, bleaker, as all angles come out too large, but, nevertheless, encouraging, because theta_{12} decreases as the top mass increases. Whether other super-heavy fermions could drag it down to realistic values stays an open issue, together with the role of higher order corrections. The same type of counterterms that turned off the 4th order static corrections to the quark electric dipole moment are, here too, needed, in particular to stabilize quantum corrections to mixing angles.
Symmetry-protected topological $left(SPTright)$ phases are gapped short-range entangled states with symmetry $G$, which can be systematically described by group cohomology theory. $SU(3)$ and $SU(2)times{U(1)}$ are considered as the basic groups of Quantum Chromodynamics and Weak-Electromagnetic unification, respectively. In two dimension $(2D)$, nonlinear-sigma models with a quantized topological Theta term can be used to describe nontrivial SPT phases. By coupling the system to a probe field and integrating out the group variables, the Theta term becomes the effective action of Chern-Simons theory which can derive the response current density. As a result, the current shows a spin Hall effect, and the quantized number of the spin Hall conductance of SPT phases $SU(3)$ and $SU(2)times{U(1)}$ are same. In addition, relationships between $SU(3)$ and $SU(2)times{U(1)}$ which maps $SU(3)$ to $SU(2)$ with a rotation $U(1)$ will be given.
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