Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userFermion spectrum and $g-2$ anomalies in a low scale 3-3-1 model
72
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We propose a renormalizable theory based on the $SU(3)_Ctimes SU(3)_Ltimes U(1)_X$ gauge symmetry, supplemented by the spontaneously broken $U(1)_{L_g}$ global lepton number symmetry and the $S_3 times Z_2 $ discrete group, which successfully describes the observed SM fermion mass and mixing hierarchy. In our model the top and exotic quarks get tree level masses, whereas the bottom, charm and strange quarks as well as the tau and muon leptons obtain their masses from a tree level Universal seesaw mechanism thanks to their mixing with charged exotic vector like fermions. The masses for the first generation SM charged fermions are generated from a radiative seesaw mechanism at one loop level. The light active neutrino masses are produced from a loop level radiative seesaw mechanism. Our model successfully accommodates the experimental values for electron and muon anomalous magnetic dipole moments.
rate research
Read More
We propose a predictive model based on the $SU(3)_Ctimes SU(3)_Ltimes U(1)_X$ gauge symmetry, which is supplemented by the $D_4$ family symmetry and several auxiliary cyclic symmetries whose spontaneous breaking produces the observed SM fermion mass and mixing pattern. The masses of the light active neutrinos are produced by an inverse seesaw mechanism mediated by three right handed Majorana neutrinos. To the best of our knowledge the model corresponds to the first implementation of the $D_4$ family symmetry in a $SU(3)_Ctimes SU(3)_Ltimes U(1)_X$ theory with three right handed Majorana neutrinos and inverse seesaw mechanism. Our proposed model successfully accommodates the experimental values of the SM fermion mass and mixing parameters, the muon anomalous magnetic moment as well as the Higgs diphoton decay rate constraints. The consistency of our model with the muon anomalous magnetic moment requires electrically charged scalar masses at the sub TeV scale.
We show that, in frameworks of the economical 3-3-1 model, all fermions get masses. At the tree level, one up-quark and two down-quarks are massless, but the one-loop corrections give all quarks the consistent masses. This conclusion is in contradiction to the previous analysis in which, the third scalar triplet has been introduced. This result is based on the key properties of the model: First, there are three quite different scales of vacuum expectation values: $om sim {cal O}(1) mathrm{TeV}, v approx 246 mathrm{GeV}$ and $ u sim {cal O}(1) mathrm{GeV}$. Second, there exist two types of Yukawa couplings with different strengths: the lepton-number conserving couplings $h$s and the lepton-number violating ones $s$s satisfying the condition in which the second are much smaller than the first ones: $ s ll h$. With the acceptable set of parameters, numerical evaluation shows that in this model, masses of the exotic quarks also have different scales, namely, the $U$ exotic quark ($q_U = 2/3$) gains mass $m_U approx 700 $ GeV, while the $D_al$ exotic quarks ($q_{D_al} = -1/3$) have masses in the TeV scale: $m_{D_al} in 10 div 80$ TeV.
We propose an extension of the three-Higgs-doublet model (3HDM), where the Standard Model (SM) particle content is enlarged by the inclusion of two inert $SU(2)$ scalar doublets, two inert electrically neutral gauge singlet scalars, charged vector like fermions and Majorana neutrinos. These additional particles are introduced to generate the SM fermion mass hierarchy from a sequential loop suppression mechanism. In our model the top and exotic fermion masses appear at tree level, whereas the remaining fermions get their masses radiatively. Specifically, bottom, charm, tau and muon masses appear at 1-loop; the masses for the light up, down and strange quarks as well as for the electron at 2-loop and masses for the light active neutrinos at 3-loop. Our model successfully accounts for SM fermion masses and mixings and accommodates the observed Dark Matter relic density, the electron and muon anomalous magnetic moments, as well the constraints arising from charged lepton flavor violating processes. Analyzing the electroweak symmetry breaking, we use a method based on bilinears for the case of three doublets and additional singlets. The proposed model predicts charged lepton flavor violating decays within the reach of forthcoming experiments.
We show that under current experimental bound of the decays $e_arightarrow e_bgamma$, the recent experimental data of the muon anomalous magnetic dipole moment $(g-2)_{mu}$ can be explained in the framework of the 3-3-1 model with right handed neutrinos. In addition, all of these branching ratios can reach closely the recent experimental upper bounds.
The framed standard model (FSM) predicts a $0^+$ boson with mass around 20 MeV in the hidden sector, which mixes at tree level with the standard Higgs $h_W$ and hence acquires small couplings to quarks and leptons which can be calculated in the FSM apart from the mixing parameter $rho_{Uh}$. The exchange of this mixed state $U$ will contribute to $g - 2$ and to the Lamb shift. By adjusting $rho_{Uh}$ alone, it is found that the FSM can satisfy all present experimental bounds on the $g - 2$ and Lamb shift anomalies for $mu$ and $e$, and for the latter for both hydrogen and deuterium. The FSM predicts also a $1^-$ boson in the hidden sector with a mass of 17 MeV, that is, right on top of the Atomki anomaly $X$. This mixes with the photon at 1-loop level and couples thereby like a dark photon to quarks and leptons. It is however a compound state and is thought likely to possess additional compound couplings to hadrons. By adjusting the mixing parameter and the $X$s compound coupling to nucleons, the FSM can reproduce the production rate of the $X$ in beryllium decay as well as satisfy all the bounds on $X$ listed so far in the literature. The above two results are consistent in that the $U$, being $0^+$, does not contribute to the Atomki anomaly if parity and angular momentum are conserved, while $X$, though contributing to $g - 2$ and Lamb shift, has smaller couplings than $U$ and can, at first instance, be neglected there. Despite the tentative nature of the 3 anomalies in experiment and of the FSM as theory, the accommodation of the former in the latter has strengthened the credibility of both. If this FSM interpretation were correct, it would change the whole aspect of the anomalies from just curiosities to windows into a vast hitherto hidden sector comprising at least in part the dark matter which makes up the bulk of our universe.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
