Search

We propose a U (1) L model based on A 4 symmetry aiming to explain the smallness of neutrino masses as well as the quark and lepton mixing patterns. The smallness of Majorana neutrino mass is reproduced through the combination of type-I and -II seesaw mechanisms. The model can accommodate the current observed patterns of lepton and quark mixing in which the solar neutrino mixing angle and the Dirac CP violating phase are in 3 σ range for both normal hierarchy and inverted hierarchy, the Majorana violating phases are predicted to be η 1 ∈ (0.00 , 9.76) ∘ and η 2 ∈ (68.70 , 270.00) ∘ for normal hierarchy while η 1 ∈ (0.00 , 10.83) ∘ and η 2 ∈ (78.60 , 90.00) ∘ for inverted hierarchy. The obtained sum of neutrino mass and the effective Majorana neutrino mass are in good consistent with the recent limits. For quark sector, all the quark masses can get the best-fit values and all the elements of the quark mixing matrix are in agreement with the experimental constraints except the element (V CKM) 21 with a deviation about 0.25 % . [ABSTRACT FROM AUTHOR]

In this work we introduce scalar leptoquarks into the 3-3-1 model with right-handed neutrinos with the aim of solving the (g−2)μ puzzle. We show that besides the model supports leptoquarks in the octet, sextet, triplet and singlet representations, we identified that only one specif leptoquark in the singlet representation leads to flip of chirality as required to generate positive and robust contribution to the (g−2)μ. Then we calculate its contributions to (g−2)μ and to the decay process μ→eγ and discuss the results.

In this paper, we study a non-renormalizable U (1) B − L extension of the Standard Model with D 4 and Z 4 symmetries accommodating the most recent neutrino data within the type-I seesaw mechanism. The two squared mass differences and three mixing angles can get the best-fit values while the leptonic Dirac CP phase is in 1 σ range of the best-fit values for both normal and inverted orderings. The sum of active neutrino mass and the effective neutrino masses are, respectively, predicted to be ∑ m ν = 6 0. 0 3 meV , 〈 m e e 〉 = 2. 3 0 7 meV and 〈 m β 〉 = 8. 9 0 3 meV for normal ordering while ∑ m ν = 1 0 1. 2 0 meV , 〈 m e e 〉 = 4 9. 9 3 meV and 〈 m β 〉 = 4 9. 9 5 meV for inverted ordering, which are well consistent with the current experimental constraints. [ABSTRACT FROM AUTHOR]

The root of most of the technicolor (TC) problems lies in the way the ordinary fermions acquire their masses, where an ordinary fermion (f) couples to a technifermion (F) mediated by an extended technicolor (ETC) boson leading to fermion masses that vary with the ETC mass scale (M E) as 1 / M E 2 . Recently, we discussed a new approach consisting of models where TC and QCD are coupled through a larger theory, in this case the solutions of these equations are modified compared to those of the isolated equations, and TC and QCD self-energies are of the irregular form, which allows us to build models where ETC boson masses can be pushed to very high energies. In this work we extend these results for 331-TC models, in particular considering a coupled system of Schwinger–Dyson equations, we show that all technifermions of the model exhibit the same asymptotic behavior for TC self-energies. As an application we discuss how the mass splitting of the order O (100) GeV could be generated between the second and third generation of fermions. [ABSTRACT FROM AUTHOR]

The solution of the phenomenological problems of technicolor (TC) models may reside in the different dynamical behaviors of the technifermions self-energy appearing in walking (or quasi-conformal) theories. Motivated by recent results, where it is shown how the boundary conditions (BC) of the anharmonic oscillator representation of the Schwinger–Dyson gap equation (SDE) to S U (N) are directly related with the mass anomalous dimensions, and different BC cause a change in the ultraviolet asymptotic behavior of the self-energies, in this paper, we verify that it is possible to have a hard technifermion self-energy in TC models originated through radiative corrections coming from the interactions mediated by the new massive neutral and charged gauge bosons, Z ′ and U ± ± in the context of a 331-TC model. [ABSTRACT FROM AUTHOR]

The focus of this paper lies on the possible experimental tests of leptogenesis scenarios. We consider both leptogenesis generated from oscillations, as well as leptogenesis from out-of-equilibrium decays. As the Akhmedov-Rubakov-Smirnov (ARS) mechanism allows for heavy neutrinos in the GeV range, this opens up a plethora of possible experimental tests, e.g. at neutrino oscillation experiments, neutrinoless double beta decay, and direct searches for neutral heavy leptons at future facilities. In contrast, testing leptogenesis from out-of-equilibrium decays is a quite difficult task. We comment on the necessary conditions for having successful leptogenesis at the TeV-scale. We further discuss possible realizations and their model specific testability in extended seesaw models, models with extended gauge sectors, and supersymmetric leptogenesis. Not being able to test high-scale leptogenesis directly, we present a way to falsify such scenarios by focusing on their washout processes. This is discussed specifically for the left-right symmetric model and the observation of a heavy , as well as model independently when measuring washout processes at the LHC or neutrinoless double beta decay. [ABSTRACT FROM AUTHOR]

We build a supersymmetric version with gauge symmetry, where is a new charge and and are the usual baryonic and leptonic numbers. The model has three right-handed neutrinos with identical charges, and can accommodate all fermion masses at the tree level. In particular, the type I seesaw mechanism is implemented for the generation of the active neutrino masses. We obtain the mass spectra of all sectors and for the scalar one we also give the flat directions allowed by the model. [ABSTRACT FROM AUTHOR]

We analyze the anomalous quartic gauge boson couplings WWγγ and ZZγγ, described by dimension-six effective quartic Lagrangian at the LHC. The sensitivities to anomalous quartic gauge couplings aW,Z0,c/Λ2 by examining the two different photon-induced processes pp → pγp → pWγqX and pp → pγp → pZZqX with W and Z's decaying leptonically are investigated. We show that γp mode of photon-induced reactions at the LHC are able to probe these couplings to the order of 10-6-10-7 GeV-2 at 95% confidence level (C.L.) with ... = 14 TeV and for proton-proton luminosities in the range of 30-200 fb-1. [ABSTRACT FROM AUTHOR]

We will investigate some aspects of Stueckelberg's work, which have contributed to the development of modern physics. On the one hand, the definition of diffuse boundaries in the calculation of scattering amplitudes will be reviewed, and compared with the other proposals by physicists of that time. On the other hand, the applications of Stueckelberg's description of a massive vector field in the Standard Model will be discussed. [ABSTRACT FROM AUTHOR]

Basing on the general photon eigenstate and the anomaly cancellation, we have naturally explained the electric charge quantization in two models based on the SU(3)C ⊗ SU(3)L ⊗ U(1)X gauge group, namely in the minimal model and in the model with right-handed neutrinos. In addition, we have shown that the electric charges of the proton and of the electron are opposite; and the same happens with the neutron and the neutrino. We argue that the electric charge quantization in these models is closely related with the generation number problem. In fact, both problems are properly solved as the direct consequences of the fermion content under the anomaly free conditions. [ABSTRACT FROM AUTHOR]

We study the stability of the effective Higgs potential in the split supersymmetry and Little Higgs models. In particular, we study the effects of higher dimensional operators in the effective potential on the Higgs mass predictions. We find that the size and sign of the higher dimensional operators can significantly change the Higgs mass required to maintain vacuum stability in Split SUSY models. In the Little Higgs models the effects of higher dimensional operators can be large because of a relatively lower cutoff scale. Working with a specific model we find that a contribution from the higher dimensional operator with coefficient of O(1) can destabilize the vacuum. [ABSTRACT FROM AUTHOR]

We calculated lower limits on the mass of additional charged gauge bosons W′ suggested by the Sp(6) <⊗ U(1) model using direct search bounds at hadron collider. We found that M > 502 GeV. Discovery limits for W′ at future hadron collider are also studied. [ABSTRACT FROM AUTHOR]

I point out that B → X l l decays (q = s, d) are sensitive probes of possible violation of CKM unitarity. I compute the decay rates and asymmetries in a minimal extension of the Standard Model containing an additional isosinglet charge (-1/3) quark, which leads to a deviation from CKM unitarity. It is shown that even for small mixing ratios | z /( V * V )| O(10), the contribution of the tree-level Z-FCNC appearing in the model should change the rates and asymmetries significantly. Especially the CP asymmetry, A (B → X l l), can be enhanced to be few percents, while in the standard model the size is less than O(10). On the other hand, A (B → X l) is not altered so much. Constraints for the mixing ratios are extracted from the experiments of B→X ΰ for q = s and B -B mixing for q = d under the natural assumption that the couplings of the tree-level Zff are almost unity, i.e. z ∼ 1. [ABSTRACT FROM AUTHOR]