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Alonso-Gonzalez, D., Amaral, D. W. P., Bariego-Quintana, A., Cerdeño, D., & de los Rios, M. (2023). Measuring the sterile neutrino mass in spallation source and direct detection experiments. J. High Energy Phys., 12(12), 096–27pp.
Abstract: We explore the complementarity of direct detection (DD) and spallation source (SS) experiments for the study of sterile neutrino physics. We focus on the sterile baryonic neutrino model: an extension of the Standard Model that introduces a massive sterile neutrino with couplings to the quark sector via a new gauge boson. In this scenario, the inelastic scattering of an active neutrino with the target material in both DD and SS experiments gives rise to a characteristic nuclear recoil energy spectrum that can allow for the reconstruction of the neutrino mass in the event of a positive detection. We first derive new bounds on this model based on the data from the COHERENT collaboration on CsI and LAr targets, which we find do not yet probe new areas of the parameter space. We then assess how well future SS experiments will be able to measure the sterile neutrino mass and mixings, showing that masses in the range similar to 15 – 50 MeV can be reconstructed. We show that there is a degeneracy in the measurement of the sterile neutrino mixing that substantially affects the reconstruction of parameters for masses of the order of 40 MeV. Thanks to their lower energy threshold and sensitivity to the solar tau neutrino flux, DD experiments allow us to partially lift the degeneracy in the sterile neutrino mixings and considerably improve its mass reconstruction down to 9 MeV. Our results demonstrate the excellent complementarity between DD and SS experiments in measuring the sterile neutrino mass and highlight the power of DD experiments in searching for new physics in the neutrino sector.
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Karan, A., Sadhukhan, S., & Valle, J. W. F. (2023). Phenomenological profile of scotogenic fermionic dark matter. J. High Energy Phys., 12(12), 185–34pp.
Abstract: We consider the possibility that neutrino masses arise from the exchange of dark matter states. We examine in detail the phenomenology of fermionic dark matter in the singlet-triplet scotogenic model. We explore the case of singlet-like fermionic dark matter, taking into account all coannihilation effects relevant for determining its relic abundance, such as fermion-fermion and scalar-fermion coannihilation. Although this in principle allows for dark matter below 60 GeV, the latter is in conflict with charged lepton flavour violation (cLFV) and/or collider physics constraints. We examine the prospects for direct dark matter detection in upcoming experiments up to 10 TeV. Fermion-scalar coannihilation is needed to obtain viable fermionic dark matter in the 60-100 GeV mass range. Fermion-fermion and fermion-scalar coannihilation play complementary roles in different parameter regions above 100 GeV.
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Hirsch, M., Joaquim, F. R., & Vicente, A. (2012). Constrained SUSY seesaws with a 125 GeV Higgs. J. High Energy Phys., 11(11), 105–33pp.
Abstract: Motivated by the ATLAS and CMS discovery of a Higgs-like boson with a mass around 125 GeV, and by the need of explaining neutrino masses, we analyse the three canonical SUSY versions of the seesaw mechanism (type I, II and III) with CMSSM boundary conditions. In type II and III cases, SUSY particles are lighter than in the CMSSM (or the constrained type I seesaw), for the same set of input parameters at the universality scale. Thus, to explain m(h0) similar or equal to 125 GeV at low energies, one is forced into regions of parameter space with very large values of m(0), M-1/2 or A(0). We compare the squark and gluino masses allowed by the ATLAS and CMS ranges for m(h0) (extracted from the 2011-2012 data), and discuss the possibility of distinguishing seesaw models in view of future results on SUSY searches. In particular, we briefly comment on the discovery potential of LHC upgrades, for squark/gluino mass ranges required by present Higgs mass constraints. A discrimination between different seesaw models cannot rely on the Higgs mass data alone, therefore we also take into account the MEG upper limit on BR(mu -> e gamma) and show that, in some cases, this may help to restrict the SUSY parameter space, as well as to set complementary limits on the seesaw scale.
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ANTARES Collaboration(Adrian-Martinez, S. et al), Bigongiari, C., Emanuele, U., Gomez-Gonzalez, J. P., Hernandez-Rey, J. J., Lambard, G., et al. (2013). First results on dark matter annihilation in the Sun using the ANTARES neutrino telescope. J. Cosmol. Astropart. Phys., 11(11), 032–22pp.
Abstract: A search for high-energy neutrinos coming from the direction of the Sun has been performed using the data recorded by the ANTARES neutrino telescope during 2007 and 2008. The neutrino selection criteria have been chosen to maximize the selection of possible signals produced by the self-annihilation of weakly interacting massive particles accumulated in the centre of the Sun with respect to the atmospheric background. After data unblinding, the number of neutrinos observed towards the Sun was found to be compatible with background expectations. The 90% CL upper limits in terms of spin-dependent and spin-independent WIMP-proton cross-sections are derived and compared to predictions of two supersymmetric models, CMSSM and MSSM-7. The ANTARES limits are comparable with those obtained by other neutrino observatories and are more stringent than those obtained by direct search experiments for the spin-dependent WIMP-proton cross-section in the case of hard self-annihilation channels (W+W-, tau(+)tau(-)).
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Di Valentino, E., Melchiorri, A., & Mena, O. (2013). Dark radiation sterile neutrino candidates after Planck data. J. Cosmol. Astropart. Phys., 11(11), 018–13pp.
Abstract: Recent Cosmic Microwave Background (CMB) results from the Planck satellite, combined with previous CMB data and Hubble constant measurements from the Hubble Space Telescope, provide a constraint on the effective number of relativistic degrees of freedom 3.62(-0.48)(+0.50) at 95% CL. New Planck data provide a unique opportunity to place limits on models containing relativistic species at the decoupling epoch. We present here the bounds on sterile neutrino models combining Planck data with galaxy clustering information. Assuming N-eff active plus sterile massive neutrino species, in the case of a Planck+WP+HighL+HST analysis we find m(nu,sterile)(eff) < 0.36 eV and 3.14 < N-eff < 4.15 at 95% CL, while using Planck+WP+HighL data in combination with the full shape of the galaxy power spectrum from the Baryon Oscillation Spectroscopic Survey BOSS Data Relase 9 measurements, we find that 3.30 < N-eff < 4.43 and m(nu,sterile)(eff) < 0.33 eV both at 95% CL with the three active neutrinos having the minimum mass allowed in the normal hierarchy scheme, i.e. Sigma m(nu) similar to 0.06 eV. These values compromise the viability of the (3 + 2) massive sterile neutrino models for the parameter region indicated by global fits of neutrino oscillation data. Within the (3 + 1) massive sterile neutrino scenario, we find m(nu,sterile)(eff) < 0.34 eV at 95% CL. While the existence of one extra sterile massive neutrino state is compatible with current oscillation data, the values for the sterile neutrino mass preferred by oscillation analyses are significantly higher than the current cosmological bound. We review as well the bounds on extended dark sectors with additional light species based on the latest Planck CMB observations.
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ANTARES Collaboration(Adrian-Martinez, S. et al), Barrios-Marti, J., Gomez-Gonzalez, J. P., Hernandez-Rey, J. J., Lambard, G., Mangano, S., et al. (2014). Constraining the neutrino emission of gravitationally lensed Flat-Spectrum Radio Quasars with ANTARES data. J. Cosmol. Astropart. Phys., 11(11), 017–12pp.
Abstract: This paper proposes to exploit gravitational lensing effects to improve the sensitivity of neutrino telescopes to the intrinsic neutrino emission of distant blazar populations. This strategy is illustrated with a search for cosmic neutrinos in the direction of four distant and gravitationally lensed Flat-Spectrum Radio Quasars. The magnification factor is estimated for each system assuming a singular isothermal profile for the lens. Based on data collected from 2007 to 2012 by the ANTARES neutrino telescope, the strongest constraint is obtained from the lensed quasar B0218+357, providing a limit on the total neutrino luminosity of this source of 1.08 x 10(46) erg s(-1) This limit is about one order of magnitude lower than those previously obtained in the ANTARES standard point source searches with non-lensed Flat-Spectrum Radio Quasars.
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Herrero-Garcia, J., Rius, N., & Santamaria, A. (2016). Higgs lepton flavour violation: UV completions and connection to neutrino masses. J. High Energy Phys., 11(11), 084–45pp.
Abstract: We study lepton violating Higgs (HLFV) decays, first from the effective field theory (EFT) point of view, and then analysing the different high-energy realizations of the operators of the EFT, highlighting the most promising models. We argue why two Higgs doublet models can have a BR(h -> tau mu) similar to 0:01, and why this rate is suppressed in all other realizations including vector-like leptons. We further discuss HLFV in the context of neutrino mass models: in most cases it is generated at one loop giving always BR (h -> tau mu) < 10(-4) and typically much less, which is beyond experimental reach. However, both the Zee model and extended left-right symmetric models contain extra SU(2) doublets coupled to leptons and could in principle account for the observed excess, with interesting connections between HLFV and neutrino parameters.
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Double Chooz collaboration(Abe, Y. et al), & Novella, P. (2016). Characterization of the spontaneous light emission of the PMTs used in the Double Chooz experiment. J. Instrum., 11, P08001–25pp.
Abstract: During the commissioning of the first of the two detectors of the Double Chooz experiment, an unexpected and dominant background caused by the emission of light inside the optical volume has been observed. A specific study of the ensemble of phenomena called Light Noise has been carried out in-situ, and in an external laboratory, in order to characterize the signals and to identify the possible processes underlying the effect. Some mechanisms of instrumental noise originating from the PMTs were identified and it has been found that the leading one arises from the light emission localized on the photomultiplier base and produced by the combined effect of heat and high voltage across the transparent epoxy resin covering the electric components. The correlation of the rate and the amplitude of the signal with the temperature has been observed. For the first detector in operation the induced background has been mitigated using online and offline analysis selections based on timing and light pattern of the signals, while a modification of the photomultiplier assembly has been implemented for the second detector in order to blacken the PMT bases.
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Di Bari, P., Ludl, P. O., & Palomares-Ruiz, S. (2016). Unifying leptogenesis, dark matter and high-energy neutrinos with right-handed neutrino mixing via Higgs portal. J. Cosmol. Astropart. Phys., 11(11), 044–41pp.
Abstract: We revisit a model in which neutrino masses and mixing are described by a two right-handed (RH) neutrino seesaw scenario, implying a strictly hierarchical light neutrino spectrum. A third decoupled RH neutrino, N-DM with mass M-DM, plays the role of cold dark matter (DM) and is produced by the mixing with a source RH neutrino, Ns with mass M-S, induced by Higgs portal interactions. The same interactions are also responsible for N-DM decays. We discuss in detail the constraints coming from DM abundance and stability conditions showing that in the hierarchical case, for M-DM >> M-S, there is an allowed window on M-DM values necessarily implying a contribution, from DM decays, to the high-energy neutrino flux recently detected by IceCube. We also show how the model can explain the matter-antimatter asymmetry of the Universe via leptogenesis in the quasi-degenerate limit. In this case, the DM mass should be within the range 300 GeV less than or similar to M-S < M-DM < 10PeV. We discuss the specific properties of this high-energy neutrino flux and show the predicted event spectrum for two exemplary cases. Although DM decays, with a relatively hard spectrum, cannot account for all the IceCube high-energy data, we illustrate how this extra source of high-energy neutrinos could reasonably explain some potential features in the observed spectrum. In this way, this represents a unified scenario for leptogenesis and DM that could be tested during the next years with more high-energy neutrino events.
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KM3NeT Collaboration(Adrian-Martinez, S. et al), Barrios-Marti, J., Calvo, D., Hernandez-Rey, J. J., Illuminati, G., Lotze, M., et al. (2016). A method to stabilise the performance of negatively fed KM3NeT photomultipliers. J. Instrum., 11, P12014–12pp.
Abstract: The KM3NeT research infrastructure, currently under construction in the Mediterranean Sea, will host neutrino telescopes for the identification of neutrino sources in the Universe and for studies of the neutrino mass hierarchy. These telescopes will house hundreds of thousands of photomultiplier tubes that will have to be operated in a stable and reliable fashion. In this context, the stability of the dark counts has been investigated for photomultiplier tubes with negative high voltage on the photocathode and held in insulating support structures made of 3D printed nylon material. Small gaps between the rigid support structure and the photomultiplier tubes in the presence of electric fields can lead to discharges that produce dark count rates that are highly variable. A solution was found by applying the same insulating varnish as used for the high voltage bases directly to the outside of the photomultiplier tubes. This transparent conformal coating provides a convenient and inexpensive method of insulation.
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