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Register a new userInterference Effect in LNV and LNC Meson Decays for Left Right Symmetric Model
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We study the effect of interference on the lepton number violating~(LNV) and lepton number conserving~(LNC) three-body meson decays $M_1^{+}to l_i^{+} l_j^{pm}pi^{mp}$, that arise in a TeV scale Left Right Symmetric model~(LRSM) with degenerate or nearly degenerate right handed~(RH) neutrinos. LRSM contains three RH neutrinos and a RH gauge boson. The RH neutrinos with masses in the range of $M_N sim$ (MeV - few GeV) can give resonant enhancement in the semi-leptonic LNV and LNC meson decays. In the case, where only one RH neutrino contributes to these decays, the predicted new physics branching ratio of semi-leptonic LNV and LNC meson decays $M_1^{+}to l_i^{+} l_j^{+}pi^{-}$ and $M_1^{+}to l_i^{+} l_j^{-}pi^{+}$ are equal. We find that with at least two RH neutrinos contributing to the process, the LNV and LNC decay rates can differ. Depending on the neutrino mixing angles and $CP$ violating phases, the branching ratios of LNV and LNC decay channels mediated by the heavy neutrinos can be either enhanced or suppressed, and the ratio of these two rates can differ from unity.
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We consider type I+II seesaw mechanism, where the exchanges of both right-handed neutrinos and isotriplet Higgs bosons contribute to the neutrino mass. Working in the left-right symmetric framework and assuming the mass matrix of light neutrinos $m_ u$ and the Dirac-type Yukawa couplings to be known, we find the triplet Yukawa coupling matrix $f$, which carries the information about the masses and mixing of the right-handed neutrinos. We show that in this case there exists a duality: for any solution $f$, there is a dual solution $hat{f}=m_ u/v_L-f$, where $v_L$ is the VEV of the triplet Higgs. Thus, unlike in pure type I (II) seesaw, there is no unique allowed structure for the matrix $f$. For $n$ lepton generations the number of solutions is $2^n$. We develop an exact analytic method of solving the seesaw non-linear matrix equation for $f$.
In this paper we take B-L supersymmetric standard model (B-LSSM) and TeV scale left-right symmetric model (LRSM) as two types of typical ones beyond SM to study the nuclear neutrinoless double beta decays ($0 u2beta$) and to see the senses for the present data and the expected data in the near future of the decays. In the study we pay much attention onto the QCD corrections in the energy-scale region from $mu=M_W$ to $musimeq 1.0;$GeV, but we treat the nuclear effects in the decays as done in the relevant literatures. For these two models the decay half-life of the nuclei, $^{76}$Ge and $^{136}$Xe, $T^{0 u}_{1/2}$($^{76}$Ge, $^{136}$Xe), are precisely estimated with the model parameters allowed by experiments and the results are presented properly. Results show that the concerned QCD corrections to the half-life of the $0 u2beta$ decays for the two models are quite sizable. The interference effects between the different contributions happened only in the model LRSM are specially analyzed. According to the numerical results, an optimistic conclusion is obtained that the $0 u2beta$ decays for the models may be observed in the next generation of the underground observations.
We develop a minimal left-right symmetric model based on the gauge group $SU(3)_C otimes SU(2)_L otimes SU(2)_R otimes U(1)_{B-L}$ wherein the Higgs triplets conventionally employed for symmetry breaking are replaced by Higgs doublets. Majorana masses for the right-handed neutrinos $( u_R$) are induced via two-loop diagrams involving a charged scalar field $eta^+$. This setup is shown to provide excellent fits to neutrino oscillation data via the seesaw mechanism for the entire range of the $W_R^pm$ mass, from TeV to the GUT scale. When the $W_R^pm$ mass is at the TeV scale, the $ u_R$ masses turn out to be in the MeV range. We analyze constraints from low energy experiments, early universe cosmology and from supernova 1987a on such a scenario and show its consistency. We also study collider implications of a relatively light $eta^+$ scalar through its decay into multi-lepton final states and derive a lower limit of 390 GeV on its mass from the LHC, which can be improved to 555 GeV in its high luminosity run.
We derive analytic necessary and sufficient conditions for the vacuum stability of the left-right symmetric model by using the concepts of copositivity and gauge orbit spaces. We also derive the conditions sufficient for successful symmetry breaking and the existence of a correct vacuum. We then compare results obtained from the derived conditions with those from numerical minimization of the scalar potential. Finally, we discuss the renormalization group analysis of the scalar quartic couplings through an example study that satisfies vacuum stability, perturbativity, unitarity and experimental bounds on the physical scalar masses.
We present a minimal left-right symmetric flavor model and analyze the predictions for the neutrino sector. In this scenario, the Yukawa sector is shaped by the dihedral $D_4$ symmetry which leads to correlations for the neutrino mixing parameters. We end up with four possible solutions within this model. We further analyzed the impact of the upcoming long-baseline neutrino oscillation experiment DUNE. Due to its high sensitivity, DUNE will be able to rule out two of the solutions. Finally, the prediction for the neutrinoless double beta decay for the model has also been examined.
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