Unraveling the Dirac Neutrino with Cosmological and Terrestrial Detectors

Adshead, Peter; Cui, Yanou; Long, Andrew J.; Shamma, Michael

doi:10.48550/arxiv.2009.07852

Cited by 8 publications

(9 citation statements)

References 63 publications

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“…When T drops below m H 0 ,A m H + , on the other hand, the effective fourneutrino interaction Γ ν L ν s,R mediated by the neutral scalars can still be strong enough to maintain the thermalization of ν s,R . As a consequence, ν s,R can play the role of extra radiation in affecting the Hubble expansion both at the early BBN and at the late CMB epoch, which can be parameterized by a shift of the effective neutrino number [26][27][28][29][30]:…”

Section: Mimicking the H0 Solution Via An Effective Neutrino Number S...mentioning

confidence: 99%

“…Despite the intensive focus on Majorana neutrinos during the past decades, the topics with neutrinos treated as being of Dirac nature are attracting much attention, especially in connection with the big-bang nucleosynthesis (BBN) and cosmic microwave background (CMB) [26][27][28][29][30], as well as the baryon asymmetry of the Universe [31,32]. The Dirac neutrino effects in the b → sµ + µ − process have been noticed in Ref.…”

Section: Introductionmentioning

confidence: 99%

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Linking the $R_{K^{(\ast)}}$ anomalies to the Hubble tension via a single right-handed neutrino

Duan¹,

Li²,

Li³

et al. 2021

Preprint

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The recently updated measurement from LHCb has strengthened the deviation of RK , implying a stronger hint of new physics beyond the Standard Model. We show in this paper that, the longstanding R K ( * ) anomalies can be explained by Dirac neutrinos embedded in a two-Higgs-doublet model. The explanation induces a thermalized right-handed Dirac neutrino in the early Universe, which contributes as extra radiation to the Hubble expansion and prompts a shift of the effective neutrino number, N ef f . In mimicking the favored scenarios for resolving the Hubble (H0) tension, we show that the simultaneous explanation of R K ( * ) anomalies and H0 tension via one flavor righthanded Dirac neutrino can be readily tested or ruled out by the upcoming H0 confirmation.

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Section: Mimicking the H0 Solution Via An Effective Neutrino Number S...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Linking the $R_{K^{(\ast)}}$ anomalies to the Hubble tension via a single right-handed neutrino

Duan¹,

Li²,

Li³

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…Upcoming CMB Stage IV (CMB-S4) experiments are expected to put much more stringent bounds than Planck due to their potential of probing all the way down to ∆N eff = N eff − N SM eff = 0.06 [93]. For some recent studies on light Dirac neutrinos and enhanced ∆N eff in different contexts, please see [56,[94][95][96][97][98][99][100].…”

Section: Relativistic Degrees Of Freedom N Effmentioning

confidence: 99%

Low scale Dirac leptogenesis and dark matter with observable $ΔN_{\rm eff}$

Mahanta,

Borah

2021

Preprint

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We propose a gauged B − L extension of the standard model (SM) where light neutrinos are of Dirac type by virtue of tiny Yukawa couplings with the SM Higgs. To achieve leptogenesis, we include additional heavy Majorana fermions without introducing any B − L violation by two units.An additional scalar doublet with appropriate B − L charge can allow heavy fermion coupling with the SM leptons so that out of equilibrium decay of the former can lead to generation of lepton asymmetry. Due to the B − L gauge interactions of the decaying fermion, the criteria of successful Dirac leptogenesis can also constrain the gauge sector couplings so as to keep the corresponding washout processes under control. The same B − L gauge sector parameter space can also be constrained from dark matter requirements if the latter is assumed to be a SM singlet particle with non-zero B − L charge. The same B − L gauge interactions also lead to additional thermalised relativistic degrees of freedom ∆N eff from light Dirac neutrinos which are tightly constrained by Planck 2018 data. While there exists parameter space from the criteria of successful low scale Dirac leptogenesis, dark matter and ∆N eff even after incorporating the latest collider bounds, all the currently allowed parameters can be probed by future measurements of ∆N eff .

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“…Recently, we have demonstrated that a purely thermal Dirac leptogenesis (PTDL) mechanism [3,4] can establish a more direct link between the low-energy leptonic CP violation and the highscale lepton asymmetry, where the BAU is formulated by the neutrino mixing without invoking specific Yukawa textures. In addition to the intimate relation with the BAU mystery, the right-handed Dirac neutrinos can also have a significant impact on the evolution of the early Universe, e.g., via generating the effective neutrino number shift, ∆N ef f , which is constrained by the big-band nucleosynthesis (BBN) [5][6][7][8] and cosmic microwave background (CMB) observations [9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Effective neutrino number shift from keV-vacuum neutrinophilic 2HDM

Li¹,

Li²,

Yan³

et al. 2022

Preprint

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If the Dirac neutrino masses are generated by a new scalar doublet with a vacuum at keV order, there would be rare hope to probe the framework in low-energy flavor physics, such as the lepton-flavor violating processes. However, the predicted neutrino Yukawa couplings being around the order of electronic Yukawa can realize a purely thermal Dirac leptogenesis, and thus render a more direct link between the high-and the low-energy CP violation. Despite its inert property in the low-energy flavor processes, the keV-vacuum induced Dirac neutrino model can generate a significant shift of the effective neutrino number, which can in turn be probed by the big-bang nucleosynthesis and cosmic microwave background epochs. We show that such a keV-vacuum induced Dirac neutrino model is already constrained by the current observations and will be probed with forecast sensitivity, serving therefore as a complementary avenue to test the Dirac leptogenesis.

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Unraveling the Dirac Neutrino with Cosmological and Terrestrial Detectors

Cited by 8 publications

References 63 publications

Linking the $R_{K^{(\ast)}}$ anomalies to the Hubble tension via a single right-handed neutrino

Linking the $R_{K^{(\ast)}}$ anomalies to the Hubble tension via a single right-handed neutrino

Low scale Dirac leptogenesis and dark matter with observable $ΔN_{\rm eff}$

Effective neutrino number shift from keV-vacuum neutrinophilic 2HDM

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