Inverse Seesaw, dark matter and the Hubble tension Fernandez-Martinez, E.; Pierre, M.; Pinsard, E. ...
The European physical journal. C, Particles and fields,
10/2021, Letnik:
81, Številka:
10
Journal Article
Recenzirano
Odprti dostop
We consider the inverse Seesaw scenario for neutrino masses with the approximate Lepton number symmetry broken dynamically by a scalar with Lepton number two. We show that the Majoron associated to ...the spontaneous symmetry breaking can alleviate the Hubble tension through its contribution to
Δ
N
eff
and late decays to neutrinos. Among the additional fermionic states required for realizing the inverse Seesaw mechanism, sterile neutrinos at the keV-MeV scale can account for all the dark matter component of the Universe if produced via freeze-in from the decays of heavier degrees of freedom.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Neutrino portals to dark matter Blennow, M.; Fernandez-Martinez, E.; Olivares-Del Campo, A. ...
The European physical journal. C, Particles and fields,
07/2019, Letnik:
79, Številka:
7
Journal Article
Recenzirano
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We explore the possibility that dark matter interactions with Standard Model particles are dominated by interactions with neutrinos. We examine whether it is possible to construct such a scenario in ...a gauge invariant manner. We first study the coupling of dark matter to the full lepton doublet and confirm that this generally leads to the dark matter phenomenology being dominated by interactions with charged leptons. We then explore two different implementations of the neutrino portal in which neutrinos mix with a Standard Model singlet fermion that interacts directly with dark matter through either a scalar or vector mediator. In the latter cases we find that the neutrino interactions can dominate the dark matter phenomenology. Present neutrino detectors can probe dark matter annihilations into neutrinos and already set the strongest constraints on these realisations. Future experiments such as Hyper-Kamiokande, MEMPHYS, DUNE, or DARWIN could allow to probe dark matter-neutrino cross sections down to the value required to obtain the correct thermal relic abundance.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A
bstract
A predictive Leptogenesis scenario is presented based on the Minimal Lepton Flavour Violation symmetry. In the realisation with three right-handed neutrinos transforming under the same ...flavour symmetry of the lepton electroweak doublets, lepton masses and PMNS mixing parameters can be described according to the current data, including a large Dirac CP phase. The observed matter-antimatter asymmetry of the Universe can be achieved through Leptogenesis, with the CP asymmetry parameter
ε
described in terms of only lepton masses, mixings and phases, plus two real parameters of the low-energy effective description. This is in contrast with the large majority of models present in the literature, where
ε
depends on several high-energy parameters, preventing a direct connection between low-energy observables and the baryon to photon ratio today. Recovering the correct amount of baryon asymmetry in the Universe constrains the Majorana phases of the PMNS matrix within specific ranges of values: clear predictions for the neutrinoless double beta decay emerge, representing a potential smoking gun for this framework.
Heavy neutral leptons are motivated by several extensions of the Standard Model and their presence induces modifications in the lepton mixing matrix, including new Dirac and Majorana CP violating ...phases. It has been recently shown that these phases play an important role in lepton number and lepton flavour violating decays and transitions, with a striking impact for the predicted rates of certain observables. In this work, we now consider the potential role of the heavy neutral fermions and of the new CP violating phases in Higgs and
Z
-boson lepton flavour violating decays
H
,
Z
→
ℓ
α
±
ℓ
β
∓
, as well as in the corresponding CP asymmetries. In order to allow for a thorough analysis, we derive the full analytical expressions of the latter observables, taking into account the effect of the (final state) charged lepton masses. A comprehensive exploration of lepton flavour violating
Z
and Higgs decays confirms that these are very sensitive to the presence of the additional heavy neutral leptons. Moreover, the new CPV phases have a clear impact on the decay rates, leading to both destructive and constructive interferences. Interestingly, in the
μ
τ
sector, the
Z
→
ℓ
α
±
ℓ
β
∓
rates are within reach of FCC-ee, with associated CP asymmetries that can potentially reach up to 20–30%.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We study lepton flavour universality violation in SM boson decays in low-scale seesaw models of neutrino mass generation, also addressing other electroweak precision observables. We compute the ...electroweak next-to-leading order corrections, which turn out to be important – notably in the case of the invisible decay width of the
Z
boson, for which the corrections can be as large as the current experimental uncertainty. As a well-motivated illustrative study case, we choose a realisation of the Inverse Seesaw mechanism, and discuss the complementary role of lepton flavour conserving, lepton flavour violating and precision observables, both in constraining and in probing such models of neutrino mass generation. Our findings suggest that invisible
Z
decays are especially important, potentially at the origin of the most stringent constraints for certain regimes of the Inverse Seesaw (while complying with charge lepton flavour violation and other electroweak precision tests). We also discuss the probing power of the considered observables in view of the expected improvement in experimental precision at FCC-ee.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A
bstract
We present a detailed study of the production of dark matter in the form of a sterile neutrino via freeze-in from decays of heavy right-handed neutrinos. Our treatment accounts for thermal ...effects in the effective couplings, generated via neutrino mixing, of the new heavy neutrinos with the Standard Model gauge and Higgs bosons and can be applied to several low-energy fermion seesaw scenarios featuring heavy neutrinos in thermal equilibrium with the primordial plasma. We find that the production of dark matter is not as suppressed as to what is found when considering only Standard Model gauge interactions. Our study shows that the freeze-in dark matter production could be efficient.
Physics potential of the ESSνSB Blennow, M.; Fernandez-Martinez, E.; Ota, T. ...
The European physical journal. C, Particles and fields,
03/2020, Letnik:
80, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The ESS
ν
SB project proposes to base a neutrino “Super Beam” of unprecedented luminosity at the European Spallation Source. The original proposal identified the second peak of the oscillation ...probability as the optimal to maximize the discovery potential to leptonic CP violation. However this choice reduces the statistics at the detector and penalizes other complementary searches such as the determination of the atmospheric oscillation parameters, particularly the octant of
θ
23
as well as the neutrino mass ordering. We explore how these shortcomings can be alleviated by the combination of the beam data with the atmospheric neutrino sample that would also be collected at the detector. We find that the combination not only improves very significantly these drawbacks, but also enhances both the CP violation discovery potential and the precision in the measurement of the CP violating phase, for which the facility was originally optimized, by lifting parametric degeneracies. We then reassess the optimization of the ESS
ν
SB setup when the atmospheric neutrino sample is considered, with an emphasis in performing a measurement of the CP violating phase as precise as possible. We find that for the presently preferred value of
δ
∼
-
π
/
2
, shorter baselines and longer running time in neutrino mode would be optimal. In these conditions, a measurement better than
14
∘
would be achievable for any value of the
θ
23
octant and the mass ordering. Conversely, if present and next generation facilities were not able to discover CP violation, longer baselines and more even splitting between neutrino and neutrino modes would be preferable. These choices would allow a
5
σ
discovery of CP violation for around a
60
%
of the possible values of
δ
and to determine its value with a precision around
6
∘
if it is close to 0 or
π
.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A
bstract
We explore the sensitivity to new physics of the recently proposed vIOLETA experiment: a 10 kg Skipper Charged Coupled Device detector deployed 12 meters away from a commercial nuclear ...reactor core. We investigate two broad classes of models which benefit from the very low energy recoil threshold of these detectors, namely neutrino magnetic moments and light mediators coupled to neutrinos and quarks or electrons. We find that this experimental setup is very sensitive to light, weakly coupled new physics, and in particular that it could probe potential explanations of the event excess observed in XENON1T. We also provide a detailed study on the dependence of the sensitivity on the experimental setup assumptions and on the neutrino flux systematic uncertainties.
We perform a comprehensive scan of the parameter space of a general singlet scalar extension of the Standard Model to identify the regions which can lead to a strong first-order phase transition, as ...required by the electroweak baryogenesis mechanism. We find that taking into account bubble nucleation is a fundamental constraint on the parameter space and present a conservative and fast estimate for it so as to enable efficient parameter space scanning. The allowed regions turn out to be already significantly probed by constraints on the scalar mixing from Higgs signal strength measurements. We also consider the addition of new neutrino singlet fields with Yukawa couplings to both scalars and forming heavy (pseudo)-Dirac pairs, as in the linear or inverse Seesaw mechanisms for neutrino mass generation. We find that their inclusion does not alter the allowed parameter space from early universe phenomenology in a significant way. Conversely, there are allowed regions of the parameter space where the presence of the neutrino singlets would remarkably modify the collider phenomenology, yielding interesting new signatures in Higgs and singlet scalar decays.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Recently, Belle II reported on the first measurement of B(B±→K±νν¯) which appears to be almost 3σ larger than predicted in the Standard Model. We point out the important correlation with B(B→K⁎νν¯) ...so that the measurement of that decay mode could help restrain the possible options for building the model of New Physics. We interpret this new experimental result in terms of physics beyond the Standard Model by using SMEFT and find that a scenario with coupling only to τ can accommodate the current experimental constraints but fails in getting a desired RD(⁎)exp/RD(⁎)SM, unless one turns the other SMEFT operators that are not related to b→sℓℓ or/and b→sνν.
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