ANTARES Collaboration(Albert, A. et al), Alves, S., Carretero, V., Colomer, M., Gozzini, R., Hernandez-Rey, J. J., et al. (2021). Measurement of the atmospheric nu(e) and nu(mu) energy spectra with the ANTARES neutrino telescope. Phys. Lett. B, 816, 136228–7pp.
Abstract: This letter presents a combined measurement of the energy spectra of atmospheric nu(e) and nu(mu) in the energy range between similar to 100 GeV and similar to 50 TeV with the ANTARES neutrino telescope. The analysis uses 3012 days of detector livetime in the period 2007-2017, and selects 1016 neutrinos interacting in (or close to) the instrumented volume of the detector, yielding shower-like events (mainly from nu(e) + (nu) over bar (e) charged current plus all neutrino neutral current interactions) and starting track events (mainly from nu(mu) + (nu) over bar (mu) charged current interactions). The contamination by atmospheric muons in the final sample is suppressed at the level of a few per mill by different steps in the selection analysis, including a Boosted Decision Tree classifier. The distribution of reconstructed events is unfolded in terms of electron and muon neutrino fluxes. The derived energy spectra are compared with previous measurements that, above 100 GeV, are limited to experiments in polar ice and, for nu(mu), to Super-Kamiokande.
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ANTARES Collaboration(Albert, A. et al), Alves, S., Calvo, D., Carretero, V., Gozzini, R., Hernandez-Rey, J. J., et al. (2023). Hint for a TeV neutrino emission from the Galactic Ridge with ANTARES. Phys. Lett. B, 841, 137951–7pp.
Abstract: Interactions of cosmic ray protons, atomic nuclei, and electrons in the interstellar medium in the inner part of the Milky Way produce gamma-ray flux from the Galactic Ridge. If the gamma-ray emission is dominated by proton and nuclei interactions, a neutrino flux comparable to the gamma-ray flux is expected from the same sky region. Data collected by the ANTARES neutrino telescope are used to constrain the neutrino flux from the Galactic Ridge in the 1-100 TeV energy range. Neutrino events reconstructed both as tracks and showers are considered in the analysis and the selection is optimized for the search of an excess in the region |l| < 30 degrees, |b| < 2 degrees. The expected background in the search region is estimated using an off-zone region with similar sky coverage. Neutrino signal originating from a power-law spectrum with spectral index ranging from Gamma nu = 1to 4is simulated in both channels. The observed energy distributions are fitted to constrain the neutrino emission from the Ridge. The energy distributions in the signal region are inconsistent with the background expectation at similar to 96% confidence level. The mild excess over the background is consistent with a neutrino flux with a power law with a spectral index 2.45(-0.34)(+0.22) and a flux normalization dN nu/dE nu= 4.0(-2.0)(+2.7) x 10(-16) GeV-1 cm(-2) s(-1) sr(-1) at 40 TeV reference energy. Such flux is consistent with the expected neutrino signal if the bulk of the observed gamma-ray flux from the Galactic Ridge originates from interactions of cosmic ray protons and nuclei with a power-law spectrum extending well into the PeV energy range.
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ANTARES Collaboration(Albert, A. et al), Barrios-Marti, J., Hernandez-Rey, J. J., Illuminati, G., Lotze, M., Tönnis, C., et al. (2017). Results from the search for dark matter in the Milky Way with 9 years of data of the ANTARES neutrino telescope. Phys. Lett. B, 769, 249–254.
Abstract: Using data recorded with the ANTARES telescope from 2007 to 2015, a new search for dark matter annihilation in the Milky Way has been performed. Three halo models and five annihilation channels, WIMP + WIMP -> b (b) over bar, W+W-, tau(+)tau(-), mu(+)mu(-) and v (v) over bar, with WIMP masses ranging from 50 2 GeV/C-2 to 100 Tev/C-2, were considered. No excess over the expected background was found, and limits on the thermally averaged annihilation cross-section were set.
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ANTARES Collaboration(Albert, A. et al), Colomer, M., Gozzini, R., Hernandez-Rey, J. J., Illuminati, G., Khan-Chowdhury, N. R., et al. (2020). Search for dark matter towards the Galactic Centre with 11 years of ANTARES data. Phys. Lett. B, 805, 135439–6pp.
Abstract: Neutrino detectors participate in the indirect search for the fundamental constituents of dark matter (DM) in form of weakly interacting massive particles (WIMPs). In WIMP scenarios, candidate DM particles can pair-annihilate into Standard Model products, yielding considerable fluxes of high-energy neutrinos. A detector like ANTARES, located in the Northern Hemisphere, is able to perform a complementary search looking towards the Galactic Centre, where a high density of dark matter is thought to accumulate. Both this directional information and the spectral features of annihilating DM pairs are entered into an unbinned likelihood method to scan the data set in search for DM-like signals in ANTARES data. Results obtained upon unblinding 3170 days of data reconstructed with updated methods are presented, which provides a larger, and more accurate, data set than a previously published result using 2101 days. A non-observation of dark matter is converted into limits on the velocity-averaged cross section for WIMP pair annihilation.
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Albertus, C., Hernandez, E., & Nieves, J. (2010). Hyperfine mixing in electromagnetic decay of doubly heavy bc baryons. Phys. Lett. B, 690(3), 265–271.
Abstract: We investigate the role of hyperfine mixing in the electromagnetic decay of ground state doubly heavy bc baryons. As in the case of a previous calculation on b -> c semileptonic decays of doubly heavy baryons, we find large corrections to the electromagnetic decay widths due to this mixing. Contrary to the weak case just mentioned, we find here that one cannot use electromagnetic width relations obtained in the infinite heavy quark mass limit to experimentally extract information on the admixtures in a model independent way.
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Albertus, C., Hernandez, E., & Nieves, J. (2011). Exclusive c -> s, d semileptonic decays of ground-state spin-1/2 doubly charmed baryons. Phys. Lett. B, 704(5), 499–509.
Abstract: We evaluate exclusive semileptonic decays of ground-state spin-1/2 doubly heavy charmed baryons driven by a c -> s, d transition at the quark level. Our results for the form factors are consistent with heavy quark spin symmetry constraints which are valid in the limit of an infinitely massive charm quark and near zero recoil. Only a few exclusive semileptonic decay channels have been theoretically analyzed before. For those cases we find that our results are in a reasonable agreement with previous calculations.
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Albertus, C., Hernandez, E., Hidalgo-Duque, C., & Nieves, J. (2014). (B)over-bar(s) -> K semileptonic decay from an Omnes improved constituent quark model. Phys. Lett. B, 738, 144–149.
Abstract: We study the f(+) form factor for the semileptonic (B) over bar (s) -> K+ l(-) (V) over bar (l) decay in a constituent quark model. The valence quark estimate is supplemented with the contribution from the (B) over bar* pole that dominates the high q(2) region. We use a multiply-subtracted Omnes dispersion relation to extend the quark model predictions from its region of applicability near q(max)(2) = (M-Bs – M-K)(2) similar to 23.75 GeV2 to all q(2) values accessible in the physical decay. To better constrain the dependence of f(+) on q(2), we fit the subtraction constants to a combined input from previous light cone sum rule by Duplancic and Melic (2008) [11] and the present quark model results. From this analysis, we obtain Gamma ( (B) over bar (s) -> K+ l(-) (V) over bar (l)) = (5.47(-0.46)(+0.54)) vertical bar Vub vertical bar(2) x 10(-9) MeV, which is about 10% and 20% higher than the predictions based on Lattice QCD and QCD light cone sum rules respectively. The former predictions, for both the form factor f(+) (q(2)) and the differential decay width, lie within the 1 sigma band of our estimated uncertainties for all q(2) values accessible in the physical decay, except for a quite small region very close to q(max)(2). Differences with the light cone sum results for the form factor f(+) are larger than 20% in the region above q(2) = 15 GeV2.
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Algora, A., Ganioglu, E., Sarriguren, P., Guadilla, V., Fraile, L. M., Nacher, E., et al. (2021). Total absorption gamma-ray spectroscopy study of the beta-decay of Hg-186. Phys. Lett. B, 819, 136438–7pp.
Abstract: The Gamow-Teller strength distribution of the decay of Hg-186 into Au-186 has been determined for the first time using the total absorption gamma spectroscopy technique and has been compared with theoretical QRPA calculations using the SLy4 Skyrme force. The measured Gamow-Teller strength distribution and the half-life are described by mixing oblate and prolate configurations independently in the parent and daughter nuclei. In this theoretical framework the best description of the experimental beta strength is obtained with dominantly prolate components for both parent Hg-186 and daughter Au-186. The approach also allowed us to determine an upper limit of the oblate component in the parent state. The complexity of the analysis required the development of a new approach in the analysis of the X-ray gated total absorption spectrum.
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Alvarado, C., Bonilla, C., Leite, J., & Valle, J. W. F. (2021). Phenomenology of fermion dark matter as neutrino mass mediator with gauged B-L. Phys. Lett. B, 817, 136292–12pp.
Abstract: We analyze a model with unbroken U(1)(B-L) gauge symmetry where neutrino masses are generated at one loop, after spontaneous breaking of a global U(1)(G) symmetry. These symmetries ensure dark matter (DM) stability and the Diracness of neutrinos. Within this context, we examine fermionic dark matter. Consistency between the required neutrino mass and the observed relic abundance indicates dark matter masses and couplings within the reach of direct detection experiments.
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Alves, A., Arcadi, G., Dong, P. V., Duarte, L., Queiroz, F. S., & Valle, J. W. F. (2017). Matter-parity as a residual gauge symmetry: Probing a theory of cosmological dark matter. Phys. Lett. B, 772, 825–831.
Abstract: We discuss a non-supersymmetric scenario which addresses the origin of the matter-parity symmetry, P-M = (-1)(3(B-L)+2s), leading to a viable Dirac fermion dark matter candidate. Implications to electroweak precision, muon anomalous magnetic moment, flavor changing interactions, lepton flavor violation, dark matter and collider physics are discussed in detail. We show that this non-supersymmetric model is capable of generating the matter-parity symmetry in agreement with existing data with gripping implications to particle physics and cosmology.
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