Probing sterile neutrinos in the framework of inverse seesaw mechanism through leptoquark productions (original) (raw)
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The presence of small neutrino masses and flavour mixings can be accounted for naturally in various models about extensions of the standard model, particularly in the seesaw mechanism models. In this work, we present a minimally extended seesaw framework with two right-handed neutrinos, where the active neutrino masses are derived in the radiative regime. Using the framework it can be shown that within certain mass limits, the light neutrino mass term can approach a form that is similar to its form under type-I seesaw mechanism. Apart from this, we show that the decay width of right-handed neutrinos (produced through the decay of [Formula: see text] boson in a particle collider) is short enough to cause a sufficiently long lifetime for the particles, thus ensuring an observable displacement in the LHC between the production and decay vertices. We comment on the fact that these displaced vertex signatures thus can serve as a means to verify the existence of these right-handed neutrin...
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The common lore in the literature of neutrino mass generation is that the canonical seesaw mechanism beautifully offers an explanation for the tiny neutrino mass but at the cost of introducing right-handed neutrinos at a scale that is out of range for the current experiments. The inverse seesaw mechanism is an interesting alternative to the canonical one once it leads to tiny neutrino masses with the advantage of being testable at TeV scale. However, this last mechanism suffers from an issue of naturalness concerning the scale responsible for such small masses, namely, the parameter µ that is related to lepton number violation and is supposed to be at the keV scale, much lower than the electroweak one. However, no theoretical framework was built that offers an explanation for obtaining this specific scale. In this work we propose a variation of the inverse seesaw mechanism by assuming a minimal scalar and fermionic set of singlet fields, along with a Z 5 ⊗ Z 2 symmetry, that allows a dynamical explanation for the smallness of µ, recovering the neat canonical seesaw formula and with right-handed (RH) neutrinos free to be at the electroweak scale, thus testable at LHC and current neutrino experiments.
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In a recent review Mohapatra has discussed how type-I seesaw mechanism suppressed by fine tuning of Yukawa couplings, or specific textures of associated fermion mass matrices, can form the basis of neutrino masses in TeV scale WRW_RWR boson models. In this paper we review recent works in another class of theories where the added presence of fermion singlets manifesting as sterile neutrinos render the type-I seesaw contribution vanishing but extended seesaw dominant where the light neutrino mass formula is same as the classic inverse seesaw but all massive neutrinos are Majorana fermions. We also show domunance of linear seesaw, or double seesaw, or type-II seesaw in due to cancellation of type-I seesaw. Embeddings of this mechnism in supersymmetric as well as non-supersymmetric SO(10) with low or intermediate masses of WRW_RWR or ZRZ_RZR bosons are discussed. We also discuss how this cancellation criteria has led to a new mechanism of type-II seesaw dominance which permits U(1)B−LU(1)_{B-L}U(1)B−L br...
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We consider a mechanism for neutrino mass generation, based on a local B − L extension of the standard model, which becomes a linear seesaw regime for light neutrinos after spontaneous symmetry breaking. The spectrum of extra particles includes heavy neutrinos with masses near the TeV scale and a heavy Z boson, as well as three extra neutral scalars and a charged scalar pair. We study the production and decays of these heavy particles at the LHC. Z will decay mainly into heavy neutrino pairs or charged lepton pairs, similar to other low scale seesaw scenarios with local B − L, while the phenomenology of the extra scalars is what distinguishes the linear seesaw from the previous models. One of the neutral scalars is produced by Z Z fusion and decays mainly into vector boson pairs, the other two neutral scalars are less visible as they decay only into heavy or light neutrino pairs, and finally the charged scalars will decay mainly into charged leptons and missing energy.
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In a recent review Mohapatra has discussed how type-I seesaw mechanism suppressed by fine tuning or specific textures of associated fermion mass matrices can form the basis of neutrino masses in TeV scale WR boson models. In this paper we review recent works in another class of theories where the added presence of fermion singlets manifesting as sterile neutrinos render the type-I seesaw contribution vanishing but extended seesaw dominant where the light neutrino mass formula is same as the inverse seesaw but all massive neutrinos are Majorana fermions. Embeddings of this mechnism in supersymmetric as well as non-supersymmetric SO(10) with low or intermediate masses of WR or ZR bosons are discussed. We also discuss how this cancellation criterion has led to a new mechanism of type-II seesaw dominance which permits U(1)B−L breaking scale much smaller than the left-handed triplet mass. Out of a number of new observable predictions, the most visible one in both cases is the dominant co...
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We study a model of neutrino within the framework of minimal extended seesaw (MES), which plays an important role in active and sterile neutrino phenomenology in (3+1) scheme. The A 4 flavor symmetry is augmented by additional Z 4 ×Z 3 symmetry to constraint the Yukawa Lagrangian of the model. We use non-trivial Dirac mass matrix, with broken µ − τ symmetry, as the origin of leptonic mixing. Interestingly, such structure of mixing naturally leads to the non-zero reactor mixing angle θ 13. Non-degenerate mass structure for right-handed neutrino M R is considered so that we can further extend our study to Leptogenesis. We have also considered three different cases for sterile neutrino mass, M S to check the viability of this model, within the allowed 3σ bound in this MES framework.