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تسجيل مستخدم جديدThe economical 3-3-1 model revisited
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We show that the economical 3-3-1 model poses a very high new physics scale of the order of 1000~TeV due to the constraint on the flavor-changing neutral current. The implications of the model for neutrino masses, inflation, leptogenesis, and superheavy dark matter are newly recognized. Alternatively, we modify the model by rearranging the third quark generation differently from the first two quark generations, as well as changing the scalar sector. The resultant model now predicts a consistent new physics at TeV scale unlike the previous case and may be fully probed at the current colliders. Particularly, due to the minimal particle contents, the models under consideration manifestly accommodate dark matter candidates and neutrino masses, with novel and distinct production mechanisms. The large flavor-changing neutral currents that come from the ordinary and exotic quark mixings can be avoided due to the approximate $B-L$ symmetry.
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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 contradict
ion 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.
By applying copositivity criterion to the scalar potential of the economical $3-3-1$ model, we derive necessary and sufficient bounded-from-below conditions at tree level. Although these are a large number of intricate inequalities for the dimensionl
ess parameters of the scalar potential, we present general enlightening relations in this work. Additionally, we use constraints coming from the minimization of the scalar potential by means of the orbit space method, the positivity of the squared masses of the extra scalars, the Higgs boson mass, the $Z$ gauge boson mass and its mixing angle with the SM $Z$ boson in order to further restrict the parameter space of this model.
We investigate the muon anomalous magnetic moment in the context of the supersymmetric version of the economical 3-3-1 model. We compute the 1-loop contribution of super-partner particles. We show that contribution of superparticle loop becomes signi
ficant when tan gamma is large. We investigate for both small and large values of $tan gamma$. We find the region of the parameter space where the slepton masses are of a few hundreds GeV is favour by the muon g-2 for small tan gamma (tan gamma sim 5 ). Numerical estimation gives the mass of supersymmetric particle, the mass of gauginos m_G sim 700 GeV and light slepton mass m_{tilde{L}} is of order O (100) GeV. When tan{gamma} is large (tan{gamma} sim 60), the mass of charged slepton m_{tilde{L}} and the mass of gauginos m_Gsim O(1) TeV while the mass of sneutrino sim 450 GeV is in the reach of LHC.
We show that in the minimal 3-3-1 model the flavor changing neutral currents (FCNCs) do not impose necessarily strong constraints on the mass of the $Z^prime$ of the model if we also consider the neutral scalar contributions to such processes, like t
he neutral mesons mass difference and rare semileptonic decays. We first obtain numerical values for all the mixing matrices of the model i.e., the unitary matrices that rotate the left- and right-handed quarks in each charge sector which give the correct mass of all the quarks and the CKM mixing matrix. Then, we find that there is a range of parameters in which the neutral scalar contributions to these processes may interfere with those of the $Z^prime$, implying this vector boson may be lighter than it has been thought.
A simple extension of the Standard Model (SM), based on the gauge group $SU(3)_Cotimes SU(3)_Lotimes U(1)_Y$ with $Y$ being the hypercharge, is considered. We show that, by imposing an approximate global $SU(2)_Ltimes SU(2)_R$ custodial symmetry at t
he SM energy scale, the $Z-Z$ mixing is absent at tree level and the value of the $rho$ parameter can be kept close to one. Tree-level flavor-changing neutral currents are also reduced to three particles, namely $Z$, a CP-odd Higgs and a CP-even Higgs. The model predicts new leptons with electric charges of $pm 1/2e$ and new quarks with $pm 1/6e$ charges as well as new gauge and scalar bosons with $pm 1/2e$ charges. Electric charge conservation requires that one of them must be stable. Their masses are unfortunately free parameters.
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