Natural 
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-portal Majorana dark matter in alternative U(1) extended standard model

Okada, Nobuchika; Okada, Satomi; Raut, Digesh

doi:10.1103/physrevd.100.035022

Cited by 37 publications

(23 citation statements)

References 71 publications

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“…It has been recently shown in Ref. [13] that in the alternative B − L model, N 3 R plays the role of DM in the Universe, reproducing the observed DM relic abundance with m N 3 ≃ m Z ′ /2. Motivated by the discussion, we set…”

supporting

confidence: 62%

Probing the seesaw mechanism at the 250 GeV ILC

Das

Okada

et al. 2019

Physics Letters B

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We consider a gauged U(1)B−L (Baryon-minus-Lepton number) extension of the Standard Model (SM), which is anomaly-free in the presence of three Right-Handed Neutrinos (RHNs). Associated with the U(1)B−L symmetry breaking the RHNs acquire their Majorana masses and then play the crucial role to generate the neutrino mass matrix by the seesaw mechanism. Towards the experimental confirmation of the seesaw mechanism, we investigate a RHN pair production through the U(1)B−L gauge boson (Z ′ ) at the 250 GeV International Linear Collider (ILC). The Z ′ gauge boson has been searched at the Large Hadron Collider (LHC) Run-2 and its production cross section is already severely constrained. The constraint will become more stringent by the future experiments with the High-Luminosity upgrade of the LHC (HL-LHC). We find a possibility that even after a null Z ′ boson search result at the HL-LHC, the 250 GeV ILC can search for the RHN pair production through the final state with same-sign dileptons plus jets, which is a "smoking-gun" signature from the Majorana nature of RHNs. In addition, some of RHNs are long-lived and leave a clean signature with a displaced vertex. Therefore, the 250 GeV ILC can operate as not only a Higgs Factory but also a RHN discovery machine to explore the origin of the Majorana neutrino mass generation, namely the seesaw mechanism.

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supporting

confidence: 62%

Probing the seesaw mechanism at the 250 GeV ILC

Das

Okada

et al. 2019

Physics Letters B

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“…In this way, if only extra vector-like fermions are allowed beyond the SM (r = 0) the solution must be proportional to hypercharge. Without lost of generality, we can write the solutions in terms of just one parameter [53][54][55], that we choose to be l after fix r = 1. Then, as shown in the Appendix, the full family of solutions for a fixed l can be obtained after rescaling all the X-charges by a factor r. In particular, the fermiophobic [28][29][30] solution used in the previous sections, U(1) D , corresponds to the rescaling r = 0 of the U(1) R solution: D = X(0, 0).…”

Section: Beyond the Minimal Model: Cosmological And Collider Constraintsmentioning

confidence: 99%

“…[83]. In this way, without lost of generality, we will work with the normalized solution in terms of a single parameter [53][54][55] that we choose to be l, by setting r = 1 as summarized in column U(1) X of Table 2, which is just…”

Section: A U(1) X Anomaly Cancellationmentioning

confidence: 99%

Dirac neutrino mass generation from a Majorana messenger

2020

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The radiative type-I seesaw has been already implemented to explain the lightness of Majorana neutrinos with both Majorana and Dirac heavy fermions, and the lightness of Dirac neutrinos with Dirac heavy fermions. In this work we present a minimal implementation of the radiative type-I seesaw with light Dirac neutrinos and heavy Majorana fermions. An inert doublet and a complex singlet scalar complete the dark sector which is protected by an Abelian fermiophobic gauge symmetry that also forbids tree level mass contributions for the full set of light neutrinos. A fermion vector-like extension of the model is also proposed where the light right-handed neutrinos can thermalize in the primordial plasma and the extra gauge boson can be directly produced at colliders. In particular, the current upper bound on ∆N eff reported by PLANCK points to large ratios M Z /g 40 TeV which can be competitive with collider constraint for g sufficiently large in the ballpark of the Standard Model values, while future cosmic microwave background experiments may probe all the no minimal models presented here.

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“…after which the seesaw mechanism is automatically implemented. Note that because of the particle content, only two RHNs (N R 1,2 ) are involved in the seesaw mechanism (the so-called "minimal seesaw" [81][82][83][84][85]) while the third RHN (N R 3 ) has no direct coupling with the SM particles and hence it is naturally a dark matter (DM) candidate [86]. [12][13][14][15][16][17][18][19][20] or the Higgs boson [98][99][100][101][102] at the LHC is expected to be very small within the minimal seesaw.…”

Section: Gauged U (1) Extension Of the Standard Modelmentioning

confidence: 99%

“…As discussed in Ref. [86], the As in Case-I, we evaluate the Z boson production cross section by using the NWA. In the left panel of Fig.…”

Section: B Case-iimentioning

confidence: 99%

Long-lived TeV-scale right-handed neutrino production at the LHC in gauged U(1) model

2019

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A gauged U (1) X extension of the Standard Model is a simple and consistent framework to naturally incorporate three right-handed neutrinos (RHNs) for generating the observed light neutrino masses and mixing by the type-I seesaw mechanism. We examine the collider testability of the U (1) X model, both in its minimal form with the conventional charges, as well as with an alternative charge assignment, via the resonant production of the U (1) X gauge boson (Z ) and its subsequent decay into a pair of RHNs. We first derive an updated upper limit on the new gauge coupling g X as a function of the Z -boson mass from the latest LHC dilepton searches. Then we identify the maximum possible cross section for the RHN pair-production under these constraints. Finally, we investigate the possibility of having one of the RHNs long-lived, even for a TeV-scale mass. Employing the general parametrization for the light neutrino mass matrix to reproduce the observed neutrino oscillation data, we perform a parameter scan and find a simple formula for the maximum RHN lifetime as a function of the lightest neutrino mass eigenvalue (m lightest ). We find that for m lightest 10 −5 eV, one of the RHNs in the minimal U (1) X scenario can be long-lived with a displaced-vertex signature which can be searched for at the LHC and/or with a dedicated longlived particle detector, such as MATHUSLA. In other words, once a long-lived RHN is observed, we can set an upper bound on the lightest neutrino mass in this model.

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Natural Z′ -portal Majorana dark matter in alternative U(1) extended standard model

Cited by 37 publications

References 71 publications

Probing the seesaw mechanism at the 250 GeV ILC

Probing the seesaw mechanism at the 250 GeV ILC

Dirac neutrino mass generation from a Majorana messenger

Long-lived TeV-scale right-handed neutrino production at the LHC in gauged U(1) model

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