Suchergebnisse

32 pages, 8 figures, 14 tables.-- Pre-print archive. ; The μνSSM provides a solution to the μ problem of the MSSM and explains the origin of neutrino masses by simply using right-handed neutrino superfields. We have completed the analysis of the vacua in this model, studying the possibility of spontaneous CP violation through complex Higgs and sneutrino vacuum expectation values. As a consequence of this process, a complex MNS matrix can be present. Besides, we have discussed the neutrino physics and the associated electroweak seesaw mechanism in the μνSSM, including also phases. Current data on neutrino masses and mixing angles can easily be reproduced. ; J.Fidalgo acknowledges the financial support of MICINN through a FPU grant. D.E. L´opez-Fogliani thanks STFC for financial support. The work of C. Munóz was supported in part by MICINN under grants FPA2006-05423 and FPA2006-01105, by the Comunidad de Madrid under grant HEPHACOS P-ESP-00346, and by the European Union under the RTN program MRTN-CT-2004-503369. ; Peer reviewed

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) ; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) ; European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant ; European Research Council under ERC Grant NuMass ; Wolfson Foundation ; Royal Society ; European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant: 690575 ; European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant: 674896 ; European Research Council under ERC Grant NuMass: FP7-IDEAS-ERC ERC-CG 617143 ; Neutrino trident scattering is a rare Standard Model process where a charged-lepton pair is produced in neutrino-nucleus scattering. To date, only the dimuon final-state has been observed, with around 100 total events, while the other channels are as yet unexplored. In this work, we compute the trident production cross section by performing a complete four-body phase space calculation for different hadronic targets. This provides a correct estimate both of the coherent and the diffractive contributions to these cross sections, but also allows us to address certain inconsistencies in the literature related to the use of the Equivalent Photon Approximation in this context. We show that this approximation can give a reasonable estimate only for the production of dimuon final-states in coherent scattering, being inadmissible for all other cases considered. We provide estimates of the number and distribution of trident events at several current and future near detector facilities subjected to intense neutrino beams from accelerators: five liquid-argon detectors (SBND, BooNE, ICARUS, DUNE and STORM), the iron detector of T2K (INGRID) and three detectors made of composite material (MINOS, NOA and MINERA). We find that for many experiments, trident measurements are an attainable goal and a valuable addition to their near detector physics programme.

We compute the one-loop running of the dimension-six CP-even Higgs operators in the Standard Model e ective eld theory involving the right-handed component of the would-be Dirac neutrinos. Then, on the basis of naturalness arguments, for some operators we obtain bounds that surpass direct constraints by orders of magnitude. We also discuss the implications of a large Dirac neutrino magnetic dipole moment. In particular, we demonstrate that a neutrino magnetic moment explaining the recent XENON1T excess induces Higgs and Z invisible decays with branching ratios in the range [10(-18); 10(-12)]. These numbers are unfortunately beyond the reach of current and near future facilities. ; Spanish MINECO under the Juan de la Cierva programme ; Spanish Government FPA2016-78220-C3-3-P ; Junta de Andalucía FQM 101 A-FQM-211-UGR18

Journal of High Energy Physics 2015.10 (2015): 130 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA) ; We perform a detailed study of the importance of loop corrections when deriving bounds on heavy-active neutrino mixing in the context of general Seesaw mechanisms with extra heavy right-handed neutrinos. We find that, for low-scale Seesaws with an approximate B − L symmetry characterized by electroweak scale Majorana masses and large Yukawas, loop corrections could indeed become relevant in a small part of the parameter space. Previous results in the literature showed that a partial cancellation between these important loop corrections and the tree level contributions could relax some constraints and lead to qualitatively different results upon their inclusion. However, we find that this cancellation can only take place in presence of large violations of the B −L symmetry, that lead to acceptably large contributions to the light neutrino masses at loop level. Thus, when we restrict our analysis of the key observables to an approximate B − L symmetry so as to recover the correct values for neutrino masses, we always find loop corrections to be negligible in the regions of the parameter space preferred by data ; We are happy to acknowledge very illuminating discussions with Mattias Blennow, Belen Gavela, Stefano Rigolin and Alfredo Urbano. We also acknowledge financial support by the European Union through the ITN INVISIBLES (PITN-GA-2011-289442). EFM and JHG also acknowledge support from the EU through the FP7 Marie Curie Actions CIG NeuProbes (PCIG11-GA-2012-321582) and the Spanish MINECO through the "Ramon y Cajal" programme (RYC2011-07710), the project FPA2009-09017 and through the Centro de excelencia Severo Ochoa Program under grant SEV-2012-0249. This work was finalized during the stay of EFM at the Aspen Center for Physics, which is supported by the National Science Foundation grant PHY-1066293. This stay was also supported by a grant from the Simons Foundation. ML thanks the IFT UAM/CSIC for the kind hospitality during the early stages of this work. JLP also acknowledges support from the INFN program on Theoretical Astroparticle Physics (TASP) and the grant 2012CPPYP7 (Theoretical Astroparticle Physics) under the program PRIN 2012 funded by the Italian Ministry of Education, University and Research (MIUR)

Journal of High Energy Physics 2013.11 (2013): 187 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA) ; We analyze the structure of quark and lepton mass matrices under the hypothesis that they are determined from a minimum principle applied to a generic potential invariant under the [SU(3)]5 ⊗ O (3) flavor symmetry, acting on Standard Model fermions and right-handed neutrinos. Unlike the quark case, we show that hierarchical masses for charged leptons are naturally accompanied by degenerate Majorana neutrinos with one mixing angle close to maximal, a second potentially large, a third one necessarily small, and one maximal relative Majorana phase. Adding small perturbations the predicted structure for the neutrino mass matrix is in excellent agreement with present observations and could be tested in the near future via neutrino-less double beta decay and cosmological measurements. The generalization of these results to arbitrary sew-saw models is also discussed ; The authors acknowledge partial support by the European Union FP7 ITN INVISIBLES (Marie Curie Actions, PITN-GA-2011-289442), as well as support from CiCYT through the project FPA2009-09017, CAM through the project HEPHACOS PESP-00346, and from European Union FP7 ITN UNILHC (Marie Curie Actions, PITN-GA-2009-237920). R.A. acknowledges MICINN support through the grant BES-2010-037869. G.I. acknowledges partial support by MIUR under project 2010YJ2NYW

Journal of High Energy Physics 2012.4 (2012): 089 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA) ; Up to now, future neutrino beam experiments have been designed and optimized in order to look for CP violation, θ13 and the mass hierarchy under the conservative assumption that θ13 is very small. However, the recent results from T2K and MINOS favor a θ13 which could be as large as 8°. In this work, we propose a re-optimization for neutrino beam experiments in case this hint is confirmed. By switching from the first to the second oscillation peak, we find that the CP discovery potential of future oscillation experiments would not only be enhanced, but it would also be less affected by systematic uncertainties. In order to illustrate the effect, we present our results for a Super-Beam experiment, comparing the results obtained at the first and the second oscillation peaks for several values of the systematic errors. We also study its combination with a β-beam facility and show that the synergy between both experiments would also be enhanced due to the larger L/E. Moreover, the increased matter effects at the longer baseline also significantly improve the sensitivity to the mass hierarchy ; We acknowledge financial support from the European Community under the European Comission Framework Programme 7, Design Study: EUROnu, Project Number 212372. The EU is not liable for any use that may be made of the information contained herein. PC has been supported by Comunidad Autónoma de Madrid, and through projects FPA2009-09017 (DGI del MCyT, Spain) and HEPHACOS S2009/ESP-1473 (Comunidad Autónoma de Madrid), as well as from the Spanish Government under the Consolider-Ingenio 2010 programme CUP, Canfranc Underground Physics, project number CSD00C-08-44022

We evaluate the probability of future neutrino oscillation facilities to discover leptonic CP violation and/or measure the neutrino mass hierarchy. We study how this probability is affected by positive or negative hints for these observables to be found at T2K and NO nu A. We consider the following facilities: LBNE; T2HK; and the 10 GeV Neutrino Factory (NF10), and show how their discovery probabilities change with the running time of T2K and NO nu A conditioned to their results. We find that, if after 15 years T2K and NO nu A have not observed a 90% CL hint of CP violation, then LBNE and T2HK have less than a 10% chance of achieving a 5 sigma discovery, whereas NF10 still has a similar to 40% chance to do so. Conversely, if T2K and NO nu A have an early 90% CL hint in 5 years from now, T2HK has a rather large chance to achieve a 5 sigma CP violation discovery (75% or 55%, depending on whether the mass hierarchy is known or not). This is to be compared with the 90% (30%) probability that NF10 (LBNE) would have to observe the same signal at 5 sigma. A hierarchy measurement at 5 sigma is achievable at both LBNE and NF10 with more than 90% probability, irrespectively of the outcome of T2K and NO nu A. We also find that if LBNE or a similar very long baseline super-beam is the only next generation facility to be built, then it is very useful to continue running T2K and NO nu A (or at least T2K) beyond their original schedule in order to increase the CP violation discovery chances, given their complementarity. ; We acknowledge very useful discussions with P. Hernandez. We also acknowledge partial support by European Union FP7 ITN INVISIBLES (Marie Curie Actions, PITN-GA-2011-289442); the Spanish MINECO through the project FPA2009-09017, the Ramon y Cajal programme (RYC-2011-07710) and the Consolider-Ingenio CUP (CSD2008-00037); the Comunidad Autonoma de Madrid through the project HEPHACOS P-ESP-00346; and by the U.S. Department of Energy under award number DE-SC0003915. ; Peer reviewed

After the successful determination of the reactor neutrino mixing angle theta(13) not equal 0.16 not equal 0, a new feature suggested by the current neutrino oscillation data is a sizeable deviation of the atmospheric neutrino mixing angle theta(23) from pi/4. Using the fact that the neutrino mixing matrix U = (UeU nu)-U-dagger, where U-e and U-nu result from the diagonalisation of the charged lepton and neutrino mass matrices, and assuming that U-nu has a i) bimaximal (BM), H) tri-bimaximal (TBM) form, or else Hi) corresponds to the conservation of the lepton charge L' = L-e - L mu - L-tau (LC), we investigate quantitatively what are the minimal forms of U-e, in terms of angles and phases it contains, that can provide the requisite corrections to U-nu so that theta(13), theta(23) and the solar neutrino mixing angle theta(12) have values compatible with the current data. Two possible orderings of the 12 and the 23 rotations in U-e, "standard" and "inverse", are considered. The results we obtain depend strongly on the type of ordering. In the case of "standard" ordering, in particular, the Dirac CP violation phase delta, present in U, is predicted to have a value in a narrow interval around i) delta similar or equal to pi in the BM (or LC) case, H) delta congruent to 3 pi/2 or pi/2 in the TBM case, the CP conserving values delta = 0, pi, 2 pi being excluded in the TBM case at more than 4 sigma. ; This work was supported in part by the INFN program on "Astroparticle Physics", the Italian MIUR program on "Neutrinos, Dark Matter and Dark Energy in the Era of LHC" the World Premier International Research Center Initiative (WPI Initiative), MEXT, Japan (S.T.P.), by the European Union FP7-ITN INVISIBLES and UNILHC (Marie Curie Action, PITAN-CA-2011-289442 and PITN-CA-2009-23792), and by the ERC Advanced Grant no. 267985 "DaMESyFla". Part of the work was done at the Galileo Galilei Institute for Theoretical Physics, Florence, Italy, which we thank for the kind hospitality and support. ; Peer reviewed

The ESS nu SB project is a proposed neutrino oscillation experiment based on the European Spallation Source with the search for leptonic CP violation as its main aim. In this letter we show that a near detector at around 1 km distance from the beamline is not only very desirable for keeping the systematic errors affecting the CP search under control, but would also provide a significant sensitivity probe for sterile neutrino oscillations in the region of the parameter space favored by the long-standing LSND anomaly. We find that the effective mixing angle theta(mu e) can be probed down to sin(2)(2 theta(mu e)) similar or equal to 2(8) . 10(-3) at 5 sigma assuming 15% bin-to-bin (un) correlated systematics. ; Goran Gustafsson Foundation ; U.S. Department of Energy [DE-SC0003915] ; European Union through FP7 Marie Curie Actions CIG NeuProbes [PCIG11-GA-2012-321582] ; European Union through ITN INVISIBLES [PITN-GA-2011-289442] ; Spanish MINECO through "Ramon y Cajal" programme [RYC2011-07710] ; Spanish MINECO [FPA2009-09017] ; Spanish MINECO (Centro de excelencia Severo Ochoa Program) [SEV-2012-0249] ; This work has been supported by the Goran Gustafsson Foundation [MB], and by the U.S. Department of Energy under award number DE-SC0003915 [PC]. EFM acknowledges financial support by the European Union through the FP7 Marie Curie Actions CIG NeuProbes (PCIG11-GA-2012-321582) and the ITN INVISIBLES (PITN-GA-2011-289442), and the Spanish MINECO through the "Ramon y Cajal" programme (RYC2011-07710) and through the project FPA2009-09017. We also thank the Spanish MINECO (Centro de excelencia Severo Ochoa Program) under grant SEV-2012-0249 as well as the Nordita Scientific program "News in Neutrino Physics", where this work was initiated.

We address the validity of the usual procedure to determine the sensitivity of neutrino oscillation experiments to CP violation. An explicit calibration of the test statistic is performed through Monte Carlo simulations for several experimental setups. We find that significant deviations from a chi(2) distribution with one degree of freedom occur for experimental setups with low sensitivity to ffi. In particular, when the allowed region to which ffi is constrained at a given confidence level is comparable to the whole allowed range, the cyclic nature of the variable manifests and the premises of Wilk's theorem are violated. This leads to values of the test statistic significantly lower than a chi(2) distribution at that confidence level. On the other hand, for facilities which can place better constraints on ffi the cyclic nature of the variable is hidden and, as the potential of the facility improves, the values of the test statistics first become slightly higher than and then approach asymptotically a chi(2) distribution. The role of sign degeneracies is also discussed. ; Goran Gustafsson Foundation ; U.S. Department of Energy [DE-SC0003915] ; European Union [PCIG11-GA-2012-321582] ; ITN INVISIBLES [PITN-GA-2011-289442] ; Spanish MINECO [RYC2011-07710, FPA2009-09017] ; We are very grateful to Thomas Schwetz for valuable discussions and encouragement. We warmly thank Peter Ballett for pointing out an inconsistency in the treatment of the systematic errors in the first version of the manuscript, and Pilar Hernandez for illuminating discussions. This work was supported by the Goran Gustafsson Foundation [MB] and by the U.S. Department of Energy under award number DE-SC0003915 [PC]. EFM acknowledges financial support by the European Union through the FP7 Marie Curie Actions CIG NeuProbes (PCIG11-GA-2012-321582) and the ITN INVISIBLES (PITN-GA-2011-289442), and the Spanish MINECO through the "Ramon y Cajal" programme (RYC2011-07710) and through the project FPA2009-09017. We also thank the Spanish MINECO (Centro de excelencia Severo Ochoa Program) under grant SEV-2012-0249 as well as the Nordita Scientific program "News in Neutrino Physics", where part of this work was performed.

16 páginas, 6 figuras.-- El Pdf del artículo es la versión pre-print: ArXiv ePrint: 1005.2275 ; We study the contribution of ν e → ν τ → τ → μ transitions to the wrong-sign muon sample of the golden channel of the Neutrino Factory. Muons from tau decays are not really a background, since they contain information from the oscillation signal, and represent a small fraction of the sample. However, if not properly handled they introduce serious systematic error, in particular if the detector/analysis are sensitive to muons of low energy. This systematic effect is particularly troublesome for large θ 13 ≥ 1° and prevents the use of the Neutrino Factory as a precision facility for large θ 13. Such a systematic error disappears if the tau contribution to the golden muon sample is taken into account. The fact that the fluxes of the Neutrino Factory are exactly calculable permits the knowledge of the tau sample due to the ν e → ν τ oscillation. We then compute the contribution to the muon sample arising from this sample in terms of the apparent muon energy. This requires the computation of a migration matrix M ij which describes the contributions of the tau neutrinos of a given energy E i , to the muon neutrinos of an apparent energy E j . We demonstrate that applying M ij to the data permits the full correction of the otherwise intolerable systematic error. ; This work was supported by the European Union under the European Commission Framework Programme 07 Design Study "EUROv", project 212372 and by the spanish ministry for Science and Innovation under the program "CUP" Consolider-Ingenio 2010, project CSD2008-0037. A.D. acknowledges funding by the spanish ministry for Science and Innovation under the project FPA2009-09017and by the Comunidad Autónoma de Madrid through project HEPHACOS-CM (S2009ESP-1473). D.M. was supported by the Deutsche Forschungs-gemeinschaft, contract WI 2639/2-1. ; Peer reviewed

Light sterile neutrinos can be probed in a number of ways, including electroweak decays, cosmology and neutrino oscillation experiments. At long-baseline experiments, the neutral-current data is directly sensitive to the presence of light sterile neutrinos: once the active neutrinos have oscillated into a sterile state, a depletion in the neutral-current data sample is expected since they do not interact with the Z boson. This channel offers a direct avenue to probe the mixing between a sterile neutrino and the tau neutrino, which is currently only weakly constrained by current data from SuperK, IceCube and NOvA, however, these constrains will continue to improve as more data is collected by these experiments. In this work, we study the potential of the DUNE experiment to constrain the mixing angle which parametrizes this mixing, theta(34), through the observation of neutral-current events at the far detector. We find that DUNE will be able to improve significantly over current constraints thanks to its large statistics and excellent discrimination between neutral- and charged-current events. ; Sao Paulo Research Foundation (FAPESP) [2014/19164-6, 2017/01749-6] ; U.S. Department Of Energy [DE-SC0013632, DE-SC0009973] ; European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant [674896] ; U.S. Department of Energy, Office of Science, Office of High Energy Physics [DE-AC02-07CH11359] ; We warmly thank Michel Sorel for providing us with the smearing matrices needed to simulate the liquid Argon detector reconstruction for neutral-current events. PC also thanks Enrique Fernandez-Martinez for useful discussions. DVF is thankful for the support of Sao Paulo Research Foundation (FAPESP) funding Grant No. 2014/19164-6 and 2017/01749-6., and also for the URA fellowship that allowed him to visit the theory department at Fermilab where this project started. DVF was also supported by the U.S. Department Of Energy under contracts DE-SC0013632 and DE-SC0009973. This work has received partial support from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 674896. This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.

Artículo escrito por muchos autores, sólo se referencian el primero, los autores que firman como Universidad Autónoma de Madrid y el grupo de colaboración en el caso de que aparezca en el artículo ; Hyper-Kamiokande will be a next-generation underground water Cherenkov detector with a total (fiducial) mass of 0.99 (0.56) million metric tons, approximately 20 (25) times larger than that of Super-Kamiokande. One of the main goals of Hyper-Kamiokande is the study of CP asymmetry in the lepton sector using accelerator neutrino and anti-neutrino beams. In this paper, the physics potential of a long-baseline neutrino experiment using the Hyper- Kamiokande detector and a neutrino beam from the J-PARC proton synchrotron is presented. The analysis uses the framework and systematic uncertainties derived from the ongoing T2K experiment. With a total exposure of 7.5 MW ×107 s integrated proton beam power (corresponding to 1.56 × 1022 protons on target with a 30 GeV proton beam) to a 2.5° off-axis neutrino beam, it is expected that the leptonic CP phase δCP can be determined to better than 19 degrees for all possible values of δCP, and CP violation can be established with a statistical significance of more than 3 σ (5 σ) for 76% (58%) of the δCP parameter space. Using both νeappearance and νμ disappearance data, the expected 1 σ uncertainty of sin2 Θ23 is 0.015(0.006) for sin2 Θ23= 0.5(0.45) ; This work was supported by a MEXT Grant-in-Aid for Scientific Research on Innovative Areas Number 25105004, titled "Unification and Development of the Neutrino Science Frontier." In addition, the participation of individual researchers has been further supported by funds from JSPS, Japan; the European Union ERC-207282, H2020 RISE-GA644294-JENNIFER, and H2020 RISE-GA641540-SKPLUS; RSF, RFBR, and MES, Russia; and JSPS and RFBR under the Japan–Russia Research Cooperative Program

The sensitivity of the Deep Underground Neutrino Experiment (DUNE) to neutrino oscillation is determined, based on a full simulation, reconstruction, and event selection of the far detector and a full simulation and parameterized analysis of the near detector. Detailed uncertainties due to the flux prediction, neutrino interaction model, and detector effects are included. DUNE will resolve the neutrino mass ordering to a precision of 5σ, for all δCP values, after 2 years of running with the nominal detector design and beam configuration. It has the potential to observe charge-parity violation in the neutrino sector to a precision of 3σ (5σ) after an exposure of 5 (10) years, for 50% of all δCP values. It will also make precise measurements of other parameters governing long-baseline neutrino oscillation, and after an exposure of 15 years will achieve a similar sensitivity to sin22θ13 to current reactor experiments. ; Fermi Research Alliance, LLC (FRA) DE-AC02-07CH11359 ; National Council for Scientific and Technological Development (CNPq) ; Carlos Chagas Filho Foundation for Research Support of the State of Rio de Janeiro (FAPERJ) ; FAPEG, Brazil ; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) ; Canada Foundation for Innovation ; IPP, Canada ; Natural Sciences and Engineering Research Council of Canada (NSERC) ; CERN ; Ministry of Education, Youth & Sports - Czech Republic Czech Republic Government ; European Union (EU) ; Centre National de la Recherche Scientifique (CNRS) ; French Atomic Energy Commission ; Istituto Nazionale di Fisica Nucleare (INFN) ; Portuguese Foundation for Science and Technology ; NRF, South Korea ; CAM, Spain ; La Caixa Foundation ; Spanish Government ; SERI, Switzerland ; Swiss National Science Foundation (SNSF) ; Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) ; Royal Society of London ; UKRI/STFC, UK ; United States Department of Energy (DOE) ; National Science Foundation (NSF) ; National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility DE-AC02-05CH11231

We explore alternative descriptions of the charged lepton sector in modular invariant models of lepton masses and mixing angles. In addition to the modulus, the symmetry breaking sector of our models includes ordinary flavons. Neutrino mass terms depend only on the modulus and are tailored to minimize the number of free parameters. The charged lepton Yukawa couplings rely upon the flavons alone. We build modular invariant models at levels 4 and 5, where neutrino masses are described both in terms of the Weinberg operator or through a type I seesaw mechanism. At level 4, our models reproduce the hierarchy among electron, muon and tau masses by letting the weights play the role of Froggatt-Nielsen charges. At level 5, our setup allows the treatment of left and right handed charged leptons on the same footing. We have optimized the free parameters of our models in order to match the experimental data, obtaining a good degree of compatibility and predictions for the absolute neutrino masses and the CP violating phases. At a more fundamental level, the whole lepton sector could be correctly described by the simultaneous presence of several moduli. Our examples are meant to make a first step in this direction. ; This project has received support in part by the MIUR-PRIN project 2015P5SBHT 003 \Search for the Fundamental Laws and Constituents" and by the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement Nº 674896 and 690575. The research of F. F. was supported in part by the INFN. The research of J. C. C. was supported by the Spanish MINECO project FPA2016-78220-C3- 1-P, the Junta de Andalucía grant FQM101 and the Spanish MECD grant FPU14.