Quasi-Dirac neutrinos at the LHC

Anamiati, Gaetana; Hirsch, Martin; Nardi, Enrico

doi:10.1007/jhep10(2016)010

Cited by 86 publications

(97 citation statements)

References 41 publications

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“…is R ll ¼ 1 or different? This question has been recently studied in some special cases [40][41][42] and was shown that due to interference between two heavy Majorana neutrino mass eigenstates, one could in principle realize a scenario with R ll anywhere between 0 and 1. The goal of this study is to do a more general analysis and discuss whether analyzing dilepton states in a hadron collider via production of a W R boson, one can probe the details of the RHN mass matrix and distinguish between the type-I and general inverse seesaw mechanisms.…”

Section: In Other Words Formentioning

confidence: 99%

Same sign versus opposite sign dileptons as a probe of low scale seesaw mechanisms

Das¹,

Dev²,

Mohapatra

2018

Phys. Rev. D

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We calculate the ratio R ll of same sign (SS) to opposite sign (OS) dileptons in type I and generalized inverse seesaw models and show that it can be anywhere between 0 and 1 depending on the detailed texture of the right-handed neutrino mass matrix. Measurement of R ll in hadron colliders can therefore provide a way to probe the nature of seesaw mechanism and also to distinguish between the two types of seesaw mechanisms. We work within the framework of left-right symmetric model as an example. We emphasize that coherence of the final states in the W R decay is crucial for this discussion and it requires the right-handed neutrinos to be highly degenerate. We isolate the range of parameters in the model where this effect is observable at the LHC and future colliders.

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Section: In Other Words Formentioning

confidence: 99%

Same sign versus opposite sign dileptons as a probe of low scale seesaw mechanisms

Das¹,

Dev²,

Mohapatra

2018

Phys. Rev. D

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“…In what concerns symmetric models, a simple yet elegant solution when y 1 = y 2 was given in [48]. We proceed to reproduce it here.…”

Section: Models With Extra Symmetries and Restrictionsmentioning

confidence: 99%

“…where we have identified the unitary matrix V = W T 1 W * 2 and the symmetric matrix y = W T 2 Y W 2 . As explained in [48], V and y are not unique, simply because the singular-value decomposition is not unique. One can always define…”

Section: Models With Extra Symmetries and Restrictionsmentioning

confidence: 99%

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General parametrization of Majorana neutrino mass models

2020

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We discuss a general formula which allows to automatically reproduce experimental data for Majorana neutrino mass models, while keeping the complete set of the remaining model parameters free for general scans, as necessary in order to provide reliable predictions for observables outside the neutrino sector. We provide a proof of this master parametrization and show how to apply it for several well-known neutrino mass models from the literature. We also discuss a list of special cases, in which the Yukawa couplings have to fulfill some particular additional conditions. * Electronic address: isabel.cordero@uv.es † Electronic address: mahirsch@ific.uv.es ‡ Electronic address: avelino.vicente@ific.uv.es

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“…For sufficiently light ( 10 GeV) HNLs like the ones accessible at SHiP, LNV may be experimentally observable even when they form a quasi-Dirac pair [24,25]. We can distinguish three cases, 2 depending on the scale of the oscillation phase δM τ , where δM is the mass splitting of the quasi-Dirac pair and τ the typical proper time probed:…”

Section: Introductionmentioning

confidence: 99%

Dirac vs. Majorana HNLs (and their oscillations) at SHiP

Tastet

Timiryasov

2020

J. High Energ. Phys.

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SHiP is a proposed high-intensity beam dump experiment set to operate at the CERN SPS. It is expected to have an unprecedented sensitivity to a variety of models containing feebly interacting particles, such as Heavy Neutral Leptons (HNLs). Two HNLs or more could successfully explain the observed neutrino masses through the seesaw mechanism. If, in addition, they are quasi-degenerate, they could be responsible for the baryon asymmetry of the Universe. Depending on their mass splitting, HNLs can have very different phenomenologies: they can behave as Majorana fermions-with lepton number violating (LNV) signatures, such as same-sign dilepton decays-or as Dirac fermions with only lepton number conserving (LNC) signatures. In this work, we quantitatively demonstrate that LNV processes can be distinguished from LNC ones at SHiP, using only the angular distribution of the HNL decay products. Accounting for spin correlations in the simulation and using boosted decision trees for discrimination, we show that SHiP will be able to distinguish Majorana-like and Dirac-like HNLs in a significant fraction of the currently unconstrained parameter space. If the mass splitting is of order 10 −6 eV, SHiP could even be capable of resolving HNL oscillations, thus providing a direct measurement of the mass splitting. This analysis highlights the potential of SHiP to not only search for feebly interacting particles, but also perform model selection.

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Quasi-Dirac neutrinos at the LHC

Cited by 86 publications

References 41 publications

Same sign versus opposite sign dileptons as a probe of low scale seesaw mechanisms

Same sign versus opposite sign dileptons as a probe of low scale seesaw mechanisms

General parametrization of Majorana neutrino mass models

Dirac vs. Majorana HNLs (and their oscillations) at SHiP

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