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Edgecock, T. R. et al, Agarwalla, S. K., Cervera-Villanueva, A., Donini, A., Ghosh, T., Gomez-Cadenas, J. J., et al. (2013). High intensity neutrino oscillation facilities in Europe. Phys. Rev. Spec. Top.-Accel. Beams, 16(2), 021002–18pp.
Abstract: The EUROnu project has studied three possible options for future, high intensity neutrino oscillation facilities in Europe. The first is a Super Beam, in which the neutrinos come from the decay of pions created by bombarding targets with a 4 MW proton beam from the CERN High Power Superconducting Proton Linac. The far detector for this facility is the 500 kt MEMPHYS water Cherenkov, located in the Frejus tunnel. The second facility is the Neutrino Factory, in which the neutrinos come from the decay of mu(+) and mu(-) beams in a storage ring. The far detector in this case is a 100 kt magnetized iron neutrino detector at a baseline of 2000 km. The third option is a Beta Beam, in which the neutrinos come from the decay of beta emitting isotopes, in particular He-6 and Ne-18, also stored in a ring. The far detector is also the MEMPHYS detector in the Frejus tunnel. EUROnu has undertaken conceptual designs of these facilities and studied the performance of the detectors. Based on this, it has determined the physics reach of each facility, in particular for the measurement of CP violation in the lepton sector, and estimated the cost of construction. These have demonstrated that the best facility to build is the Neutrino Factory. However, if a powerful proton driver is constructed for another purpose or if the MEMPHYS detector is built for astroparticle physics, the Super Beam also becomes very attractive.
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Salvatelli, V., Marchini, A., Lopez-Honorez, L., & Mena, O. (2013). New constraints on coupled dark energy from the Planck satellite experiment. Phys. Rev. D, 88(2), 023531–9pp.
Abstract: We present new constraints on coupled dark energy from the recent measurements of the cosmic microwave background anisotropies from the Planck satellite mission. We found that a coupled dark energy model is fully compatible with the Planck measurements, deriving a weak bound on the dark matter-dark energy coupling parameter xi = -0.49(-0.31)(+0.19) at 68% C.L. Moreover if Planck data are fitted to a coupled dark energy scenario, the constraint on the Hubble constant is relaxed to H-0 = 72.1(-2.3)(+3.2) km/s/Mpc, solving the tension with the Hubble Space Telescope (HST) value. We show that a combined PLANCK + HST analysis provides significant evidence for coupled dark energy finding a nonzero value for the coupling parameter xi, with -0.90 < xi < -0.22 at 95% C.L. We also consider the combined constraints from the Planck data plus the baryon acoustic oscillation measurements of the 6dF Galaxy Survey, the Sloan Digital Sky Survey and the Baron Oscillation Spectroscopic Survey.
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Diamanti, R., Lopez-Honorez, L., Mena, O., Palomares-Ruiz, S., & Vincent, A. C. (2014). Constraining dark matter late-time energy injection: decays and p-wave annihilations. J. Cosmol. Astropart. Phys., 02(2), 017–24pp.
Abstract: We use the latest cosmic microwave background (CMB) observations to provide updated constraints on the dark matter lifetime as well as on p-wave suppressed annihilation cross sections in the 1 MeV to 1 TeV mass range. In contrast to scenarios with an s-wave dominated annihilation cross section, which mainly affect the CMB close to the last scattering surface, signatures associated with these scenarios essentially appear at low redshifts (z less than or similar to 50) when structure began to form, and thus manifest at lower multipoles in the CMB power spectrum. We use data from Planck, WMAP9, SPT and ACT, as well as Lyman-alpha measurements of the matter temperature at z similar to 4 to set a 95% confidence level lower bound on the dark matter lifetime of similar to 4 x 10(25) s for m(chi) = 100 MeV. This bound becomes lower by an order of magnitude at m(chi) = 1 TeV due to inefficient energy deposition into the inter-galactic medium. We also show that structure formation can enhance the effect of p-wave suppressed annihilation cross sections by many orders of magnitude with respect to the background cosmological rate, although even with this enhancement, CMB constraints are not yet strong enough to reach the thermal relic value of the cross section.
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Escudero, M., Ramirez, H., Boubekeur, L., Giusarma, E., & Mena, O. (2016). The present and future of the most favoured inflationary models after Planck 2015. J. Cosmol. Astropart. Phys., 02(2), 020–21pp.
Abstract: The value of the tensor-to-scalar ratio r in the region allowed by the latest Planck 2015 measurements can be associated to a large variety of inflationary models. We discuss here the potential of future Cosmic Microwave Background cosmological observations in disentangling among the possible theoretical scenarios allowed by our analyses of current Planck temperature and polarization data. Rather than focusing only on r, we focus as well on the running of the primordial power spectrum, alpha(s) and the running thereof, beta(s). If future cosmological measurements, as those from the COrE mission, confirm the current best-fit value for beta(s) greater than or similar to 10(-2) as the preferred one, it will be possible to rule-out the most favoured inflationary models.
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Vincent, A. C., Palomares-Ruiz, S., & Mena, O. (2016). Analysis of the 4-year IceCube high-energy starting events. Phys. Rev. D, 94(2), 023009–18pp.
Abstract: After four years of data taking, the IceCube neutrino telescope has detected 54 high-energy starting events (HESE, or contained-vertex events) with deposited energies above 20 TeV. They represent the first detection of high-energy extraterrestrial neutrinos and, therefore, the first step in neutrino astronomy. To study the energy, flavor, and isotropy of the astrophysical neutrino flux arriving at Earth, we perform different analyses of two different deposited energy intervals, [10 TeV-10 PeV] and [60 TeV-10 PeV]. We first consider an isotropic unbroken power-law spectrum and constrain its shape, normalization, and flavor composition. Our results are in agreement with the preliminary IceCube results, although we obtain a slightly softer spectrum. We also find that current data are not sensitive to a possible neutrino-antineutrino asymmetry in the astrophysical flux. Then, we show that although a two-component power-law model leads to a slightly better fit, it does not represent a significant improvement with respect to a single power-law flux. Finally, we analyze the possible existence of a north-south asymmetry, hinted at by the combination of the HESE sample with the throughgoing muon data. If we use only HESE data, the scarce statistics from the Northern Hemisphere does not allow us to reach any conclusive answer, which indicates that the HESE sample alone is not driving the potential north-south asymmetry.
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