Observable lepton number violation with predominantly Dirac nature of active neutrinos

Borah, Debasish; Dasgupta, Arnab

doi:10.1007/jhep01(2017)072

Cited by 22 publications

(28 citation statements)

References 133 publications

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“…Many of the proposed 1-loop models are realized in a left-right symmetric context without SU(2) triplet scalars [56,390,[393][394][395][396][397][398]. Reference [399] attempted the generation of Dirac neutrino masses in the context of a model where hypercharge emerges as diagonal subgroup of U (1) L × U (1) R .…”

Section: -Loop Modelsmentioning

confidence: 99%

From the Trees to the Forest: A Review of Radiative Neutrino Mass Models

et al. 2017

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A plausible explanation for the lightness of neutrino masses is that neutrinos are massless at tree level, with their mass (typically Majorana) being generated radiatively at one or more loops. The new couplings, together with the suppression coming from the loop factors, imply that the new degrees of freedom cannot be too heavy (they are typically at the TeV scale). Therefore, in these models there are no large mass hierarchies and they can be tested using different searches, making their detailed phenomenological study very appealing. In particular, the new particles can be searched for at colliders and generically induce signals in lepton-flavor and lepton-number violating processes (in the case of Majorana neutrinos), which are not independent from reproducing correctly the neutrino masses and mixings. The main focus of the review is on Majorana neutrinos. We order the allowed theory space from three different perspectives: (i) using an effective operator approach to lepton number violation, (ii) by the number of loops at which the Weinberg operator is generated, (iii) within a given loop order, by the possible irreducible topologies. We also discuss in more detail some popular radiative models which involve qualitatively different features, revisiting their most important phenomenological implications. Finally, we list some promising avenues to pursue.

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Section: -Loop Modelsmentioning

confidence: 99%

From the Trees to the Forest: A Review of Radiative Neutrino Mass Models

et al. 2017

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“…where [81,[87][88][89][90][91][92] where spontaneous symmetry breaking is implemented with scalar bidoublet having B − L = 0 and Higgs doublets having B − L = 1 which leads to neutrino mass being generated by either simple Dirac mass terms or low scale seesaw mechanisms like inverse seesaw, linear seesaw etc. In this model, for the generation of neutrino mass we take interest in inverse seesaw mechanism since it allows large light-heavy neutrino mixing and this mixing facilitates the interaction of singly charged vector boson with heavy neutrinos which contributes positively to ∆a µ .…”

Section: The Modelmentioning

confidence: 99%

Neutrino mass, mixing and muon g − 2 explanation in $$ \mathrm{U}{(1)}_{L_{\mu }-{L}_{\tau }} $$ extension of left-right theory

Majumdar

Patra²,

Pritimita

et al. 2020

J. High Energ. Phys.

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We consider a gauged $$ \mathrm{U}{(1)}_{L_{\mu }-{L}_{\tau }} $$ U 1 L μ − L τ extension of the left-right symmetric theory in order to simultaneously explain neutrino mass, mixing and the muon anomalous magnetic moment. We get sizeable contribution from the interaction of the new light gauge boson Zμτ of the $$ \mathrm{U}{(1)}_{L_{\mu }-{L}_{\tau }} $$ U 1 L μ − L τ symmetry with muons which can individually satisfy the current bounds on muon (g − 2) anomaly (∆aμ). The other positive contributions to ∆aμ come from the interactions of singly charged gauge bosons WL, WR with heavy neutral fermions and that of neutral CP-even scalars with muons. The interaction of WL with heavy neutrino is facilitated by inverse seesaw mechanism which allows large light-heavy neutrino mixing and explains neutrino mass in our model. CP-even scalars with mass around few hundreds GeV can also satisfy the entire current muon anomaly bound. The results show that the model gives a small but non-negligible contribution to ∆aμ thereby eliminating the entire deviation in theoretical prediction and experimental result of muon (g − 2) anomaly. We have briefly presented a comparative study for symmetric and asymmetric left-right symmetric model in context of various contribution to ∆aμ. We also discuss how the generation of neutrino mass is affected when left-right symmetry breaks down to Standard Model symmetry via various choices of scalars.

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“…Some more recent works on DM in the LRSM can be found in Refs. [35][36][37][59][60][61][62][63][64][65][66]. Unlike in the triplet LRSM, where SUð2Þ R × Uð1Þ B−L gauge symmetry is spontaneously broken by a scalar triplet with even (B − L) charge (AE2), in the DLRM the same happens due to a scalar doublet with odd (B − L) charge (AE1).…”

Section: Dark Matter In Dlrmmentioning

confidence: 99%

“…While generating a sub-eV neutrino mass in this fashion requires relevant Yukawa couplings at the level of <10 −12 , we adopt this minimal scenario to study some of the interesting phenomenological consequences. Radiative generation of light Dirac neutrinos in different left-right symmetric models has also been discussed over the past few decades [32][33][34][35][36][37][38][39] which may provide a UV completion of the minimal DLRM we discuss here. Since such UV completions do not drastically change the conclusions we reach in the present work, we stick to the DLRM for the sake of simplicity.…”

Section: Introductionmentioning

confidence: 99%

Observing left-right symmetry in the cosmic microwave background

et al. 2020

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We consider the possibility of probing the left-right symmetric model (LRSM) via the cosmic microwave background (CMB). We adopt the minimal LRSM with Higgs doublets, also known as the doublet leftright model (DLRM), where all fermions including the neutrinos acquire masses only via their couplings to the Higgs bidoublet. Because of the Dirac nature of light neutrinos, there exist additional relativistic degrees of freedom which can thermalize in the early Universe by virtue of their gauge interactions corresponding to the right sector. We constrain the model from Planck 2018 bound on the effective relativistic degrees of freedom and also estimate the prospects for planned CMB stage IV experiments to constrain the model further. We find that the W R boson mass below 4.06 TeV can be ruled out from the Planck 2018 bound at 2σ C.L. in the exact left-right symmetric limit which is equally competitive as the LHC bounds from dijet resonance searches. On the other hand, the Planck 2018 bound at 1σ C.L. can rule out a much larger parameter space out of reach of present direct search experiments, even in the presence of additional relativistic degrees of freedom around the TeV corner. We also study the consequence of these constraints on dark matter in the DLRM by considering a right-handed real fermion quintuplet to be the dominant dark matter component in the Universe.

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Observable lepton number violation with predominantly Dirac nature of active neutrinos

Cited by 22 publications

References 133 publications

From the Trees to the Forest: A Review of Radiative Neutrino Mass Models

From the Trees to the Forest: A Review of Radiative Neutrino Mass Models

Neutrino mass, mixing and muon g − 2 explanation in $$ \mathrm{U}{(1)}_{L_{\mu }-{L}_{\tau }} $$ extension of left-right theory

Observing left-right symmetry in the cosmic microwave background

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