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NEXT Collaboration(Novella, P. et al), Palmeiro, B., Simon, A., Sorel, M., Martinez-Lema, G., Alvarez, V., et al. (2018). Measurement of radon-induced backgrounds in the NEXT double beta decay experiment. J. High Energy Phys., 10(10), 112–27pp.
Abstract: The measurement of the internal Rn-222 activity in the NEXT-White detector during the so-called Run-II period with Xe-136-depleted xenon is discussed in detail, together with its implications for double beta decay searches in NEXT. The activity is measured through the alpha production rate induced in the fiducial volume by Rn-222 and its alpha-emitting progeny. The specific activity is measured to be (38.1 +/- 2.2 (stat.) +/- 5.9 (syst.)) mBq/m(3). Radon-induced electrons have also been characterized from the decay of the Bi-214 daughter ions plating out on the cathode of the time projection chamber. From our studies, we conclude that radon-induced backgrounds are sufficiently low to enable a successful NEXT-100 physics program, as the projected rate contribution should not exceed 0.1 counts/yr in the neutrinoless double beta decay sample.
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Bonilla, C., Modak, T., Srivastava, R., & Valle, J. W. F. (2018). U(1)(B3-3L2) gauge symmetry as a simple description of b -> s anomalies. Phys. Rev. D, 98(9), 095002–11pp.
Abstract: We present a simple U(1)(B3-3L2) gauge standard model extension that can easily account for the anomalies in R(K) and R(K*) reported by LHCb. The model is economical in its setup and particle content. Among the standard model fermions, only the third generation quark family and the second generation leptons transform nontrivially under the new U(1)(B3-3L2) symmetry. This leads to lepton nonuniversality and flavor changing neutral currents involving the second and third quark families. We discuss the relevant experimental constraints and some implications.
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Cepedello, R., Fonseca, R. M., & Hirsch, M. (2018). Systematic classification of three-loop realizations of the Weinberg operator. J. High Energy Phys., 10(10), 197–34pp.
Abstract: We study systematically the decomposition of the Weinberg operator at three-loop order. There are more than four thousand connected topologies. However, the vast majority of these are infinite corrections to lower order neutrino mass diagrams and only a very small percentage yields models for which the three-loop diagrams are the leading order contribution to the neutrino mass matrix. We identify 73 topologies that can lead to genuine three-loop models with fermions and scalars, i.e. models for which lower order diagrams are automatically absent without the need to invoke additional symmetries. The 73 genuine topologies can be divided into two sub-classes: normal genuine ones (44 cases) and special genuine topologies (29 cases). The latter are a special class of topologies, which can lead to genuine diagrams only for very specific choices of fields. The genuine topologies generate 374 diagrams in the weak basis, which can be reduced to only 30 distinct diagrams in the mass eigenstate basis. We also discuss how all the mass eigenstate diagrams can be described in terms of only five master integrals. We present some concrete models and for two of them we give numerical estimates for the typical size of neutrino masses they generate. Our results can be readily applied to construct other d = 5 neutrino mass models with three loops.
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Reig, M., Valle, J. W. F., & Wilczek, F. (2018). SO(3) family symmetry and axions. Phys. Rev. D, 98(9), 095008–6pp.
Abstract: Motivated by the idea of comprehensive unification, we study a gauged SO(3) flavor extension of the extended Standard Model, including right-handed neutrinos and a Peccei-Quinn symmetry with simple charge assignments. The model accommodates the observed fermion masses and mixings and yields a characteristic, successful relation among them. The Peccei-Quinn symmetry is an essential ingredient.
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ANTARES and IceCube Collaborations(Albert, A. et al), Barrios-Marti, J., Coleiro, A., Colomer, M., Hernandez-Rey, J. J., Illuminati, G., et al. (2018). Joint Constraints on Galactic Diffuse Neutrino Emission from the ANTARES and IceCube Neutrino Telescopes. Astrophys. J. Lett., 868(2), L20–7pp.
Abstract: The existence of diffuse Galactic neutrino production is expected from cosmic-ray interactions with Galactic gas and radiation fields. Thus, neutrinos are a unique messenger offering the opportunity to test the products of Galactic cosmic-ray interactions up to energies of hundreds of TeV. Here we present a search for this production using ten years of Astronomy with a Neutrino Telescope and Abyss environmental RESearch (ANTARES) track and shower data, as well as seven years of IceCube track data. The data are combined into a joint likelihood test for neutrino emission according to the KRA(gamma) model assuming a 5 PeV per nucleon Galactic cosmic-ray cutoff. No significant excess is found. As a consequence, the limits presented in this Letter start constraining the model parameter space for Galactic cosmic-ray production and transport.
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