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| 2. |
- Betti, M. G., et al.
(författare)
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Neutrino physics with the PTOLEMY project : active neutrino properties and the light sterile case
- 2019
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP PUBLISHING LTD. - 1475-7516. ; :7
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Tidskriftsartikel (refereegranskat)abstract
- The PTOLEMY project aims to develop a scalable design for a Cosmic Neutrino Background (CNB) detector, the first of its kind and the only one conceived that can look directly at the image of the Universe encoded in neutrino background produced in the first second after the Big Bang. The scope of the work for the next three years is to complete the conceptual design of this detector and to validate with direct measurements that the non-neutrino backgrounds are below the expected cosmological signal. In this paper we discuss in details the theoretical aspects of the experiment and its physics goals. In particular, we mainly address three issues. First we discuss the sensitivity of PTOLEMY to the standard neutrino mass scale. We then study the perspectives of the experiment to detect the CNB via neutrino capture on tritium as a function of the neutrino mass scale and the energy resolution of the apparatus. Finally, we consider an extra sterile neutrino with mass in the eV range, coupled to the active states via oscillations, which has been advocated in view of neutrino oscillation anomalies. This extra state would contribute to the tritium decay spectrum, and its properties, mass and mixing angle, could be studied by analyzing the features in the beta decay electron spectrum.
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| 3. |
- de Salas, Pablo Fernández, et al.
(författare)
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Constraining the invisible neutrino decay with KM3NeT-ORCA
- 2019
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 789, s. 472-479
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Tidskriftsartikel (refereegranskat)abstract
- Several theories of particle physics beyond the Standard Model consider that neutrinos can decay. In this work we assume that the standard mechanism of neutrino oscillations is altered by the decay of the heaviest neutrino mass state into a sterile neutrino and, depending on the model, a scalar or a Majoron. We study the sensitivity of the forthcoming KM3NeT-ORCA experiment to this scenario and find that it could improve the current bounds coming from oscillation experiments, where three-neutrino oscillations have been considered, by roughly two orders of magnitude. We also study how the presence of this neutrino decay can affect the determination of the atmospheric oscillation parameters sin(2) theta(23) and Delta m(31)(2), as well as the sensitivity to the neutrino mass ordering.
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| 4. |
- de Salas, Pablo Fernández, et al.
(författare)
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On the estimation of the local dark matter density using the rotation curve of the Milky Way
- 2019
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP PUBLISHING LTD. - 1475-7516. ; :10
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Tidskriftsartikel (refereegranskat)abstract
- The rotation curve of the Milky Way is commonly used to estimate the local dark matter density rho(DM,circle dot). However, the estimates are subject to the choice of the distribution of baryons needed in this type of studies. In this work we explore several Galactic mass models that differ in the distribution of baryons and dark matter, in order to determine rho(DM,circle dot). For this purpose we analyze the precise circular velocity curve measurement of the Milky Way up to similar to 25 kpc from the Galactic centre obtained from Gaia DR2 [1]. We find that the estimated value of rho(DM,circle dot) stays robust to reasonable changes in the spherical dark matter halo. However, we show that rho(DM,circle dot) is affected by the choice of the model for the underlying baryonic components. In particular, we find that rho(DM,circle dot) is mostly sensitive to uncertainties in the disk components of the Galaxy. We also show that, when choosing one particular baryonic model, the estimate of rho(DM,circle dot) has an uncertainty of only about 10% of its best-fit value, but this uncertainty gets much bigger when we also consider the variation of the baryonic model. In particular, the rotation curve method does not allow to exclude the presence of an additional very thin component, that can increase rho(DM,circle dot) by more than a factor of 8 (the thin disk could even be made of dark matter). Therefore, we conclude that exclusively using the rotation curve of the Galaxy is not enough to provide a robust estimate of rho(DM,circle dot). For all the models that we study without the presence of an additional thin component, our resulting estimates of the local dark matter density take values in the range rho(DM,circle dot) similar or equal to 0.3-0.4 GeV/cm(3), consistent with many of the estimates in the literature.
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| 5. |
- Fernández de Salas, Pablo, et al.
(författare)
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Dark matter local density determination : recent observations and future prospects
- 2021
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Ingår i: Reports on progress in physics (Print). - : IOP Publishing. - 0034-4885 .- 1361-6633. ; 84:10
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Forskningsöversikt (refereegranskat)abstract
- This report summarises progress made in estimating the local density of dark matter (ρDM,⊙), a quantity that is especially important for dark matter direct detection experiments. We outline and compare the most common methods to estimate ρDM,⊙ and the results from recent studies, including those that have benefited from the observations of the ESA/Gaia satellite. The result of most local analyses coincide within a range of , while a slightly lower range of is preferred by most global studies. In light of recent discoveries, we discuss the importance of going beyond the approximations of what we define as the ideal Galaxy (a steady-state Galaxy with axisymmetric shape and a mirror symmetry across the mid-plane) in order to improve the precision of ρDM,⊙ measurements. In particular, we review the growing evidence for local disequilibrium and broken symmetries in the present configuration of the Milky Way, as well as uncertainties associated with the galactic distribution of baryons. Finally, we comment on new ideas that have been proposed to further constrain the value of ρDM,⊙, most of which would benefit from Gaia's final data release.
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| 6. |
- Gariazzo, S., et al.
(författare)
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Thermalisation of sterile neutrinos in the early universe in the 3+1 scheme with full mixing matrix
- 2019
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :7
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Tidskriftsartikel (refereegranskat)abstract
- In the framework of a 3+1 scheme with an additional inert state, we consider the thermalisation of sterile neutrinos in the early Universe taking into account the full 4 x 4 mixing matrix. The evolution of the neutrino energy distributions is found solving the momentum-dependent kinetic equations with full diagonal collision terms, as in previous analyses of flavour neutrino decoupling in the standard case. The degree of thermalisation of the sterile state is shown in terms of the effective number of neutrinos, N-eff, and its dependence on the three additional mixing angles (theta(14), theta(24), theta(34)) and on the squared mass difference Delta m(41)(2) is discussed. Our results are relevant for fixing the contribution of a fourth light neutrino species to the cosmological energy density, whose value is very well constrained by the final Planck analysis. For the preferred region of active-sterile mixing parameters from short-baseline neutrino experiments, we find that the fourth state is fully thermalised (N-eff similar or equal to 4).
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| 7. |
- Mertsch, P., et al.
(författare)
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Neutrino clustering in the Milky Way and beyond
- 2020
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :1
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Tidskriftsartikel (refereegranskat)abstract
- The standard cosmological model predicts the existence of a Cosmic Neutrino Background, which has not yet been observed directly. Some experiments aiming at its detection are currently under development, despite the tiny kinetic energy of the cosmological relic neutrinos, which makes this task incredibly challenging. Since massive neutrinos are attracted by the gravitational potential of our Galaxy, they can cluster locally. Neutrinos should be more abundant at the Earth position than at an average point in the Universe. This fact may enhance the expected event rate in any future experiment. Past calculations of the local neutrino clustering factor only considered a spherical distribution of matter in the Milky Way and neglected the influence of other nearby objects like the Virgo cluster, although recent N-body simulations suggest that the latter may actually be important. In this paper, we adopt a back-tracking technique, well established in the calculation of cosmic rays fluxes, to perform the first three-dimensional calculation of the number density of relic neutrinos at the Solar System, taking into account not only the matter composition of the Milky Way, but also the contribution of the Andromeda galaxy and the Virgo cluster. The effect of Virgo is indeed found to be relevant and to depend non-trivially on the value of the neutrino mass. Our results show that the local neutrino density is enhanced by 0.53% for a neutrino mass of 10 meV, 12% for 50 meV, 50% for 100 meV or 500% for 300 meV.
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