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Author Anamiati, G.; Fonseca, R.M.; Hirsch, M. url  doi
openurl 
  Title Quasi-Dirac neutrino oscillations Type Journal Article
  Year 2018 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 97 Issue 9 Pages 095008 - 16pp  
  Keywords  
  Abstract Dirac neutrino masses require two distinct neutral Weyl spinors per generation, with a special arrangement of masses and interactions with charged leptons. Once this arrangement is perturbed, lepton number is no longer conserved and neutrinos become Majorana particles. If these lepton number violating perturbations are small compared to the Dirac mass terms, neutrinos are quasi-Dirac particles. Alternatively, this scenario can be characterized by the existence of pairs of neutrinos with almost degenerate masses, and a lepton mixing matrix which has 12 angles and 12 phases. In this work we discuss the phenomenology of quasi-Dirac neutrino oscillations and derive limits on the relevant parameter space from various experiments. In one parameter perturbations of the Dirac limit, very stringent bounds can be derived on the mass splittings between the almost degenerate pairs of neutrinos. However, we also demonstrate that with suitable changes to the lepton mixing matrix, limits on such mass splittings are much weaker, or even completely absent. Finally, we consider the possibility that the mass splittings are too small to be measured and discuss bounds on the new, nonstandard lepton mixing angles from current experiments for this case.  
  Address [Anamiati, Gaetana; Fonseca, Renato M.; Hirsch, Martin] Univ Valencia, CSIC, Inst Fis Corpuscular, AHEP Grp, Edificio Inst Paterna,Apartado 22085, E-46071 Valencia, Spain, Email: anamiati@ific.uv.es;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000432970600004 Approved no  
  Is ISI yes International Collaboration (up) no  
  Call Number IFIC @ pastor @ Serial 3581  
Permanent link to this record
 
 
Author Hirsch, M.; Srivastava, R.; Valle, J.W.F. url  doi
openurl 
  Title Can one ever prove that neutrinos are Dirac particles? Type Journal Article
  Year 2018 Publication Physics Letters B Abbreviated Journal Phys. Lett. B  
  Volume 781 Issue Pages 302-305  
  Keywords  
  Abstract According to the “Black Box” theorem the experimental confirmation of neutrinoless double beta decay (0 nu 2 beta) would imply that at least one of the neutrinos is a Majorana particle. However, a null 0 nu 2 beta signal cannot decide the nature of neutrinos, as it can be suppressed even for Majorana neutrinos. In this letter we argue that if the null 0 nu 2 beta decay signal is accompanied by a 0 nu 2 beta quadruple beta decay signal, then at least one neutrino should be a Dirac particle. This argument holds irrespective of the underlying processes leading to such decays.  
  Address [Hirsch, Martin; Srivastava, Rahul; Valle, Jose W. F.] Univ Valencia, CSIC, Inst Fis Corpuscular, AHEP Grp, C Catedrat Jose Beltran 2, E-46980 Valencia, Spain, Email: mahirsch@ific.uv.es;  
  Corporate Author Thesis  
  Publisher Elsevier Science Bv Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0370-2693 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000435653100039 Approved no  
  Is ISI yes International Collaboration (up) no  
  Call Number IFIC @ pastor @ Serial 3632  
Permanent link to this record
 
 
Author Fonseca, R.M.; Hirsch, M. url  doi
openurl 
  Title Delta L >= 4 lepton number violating processes Type Journal Article
  Year 2018 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 98 Issue 1 Pages 015035 - 12pp  
  Keywords  
  Abstract We discuss the experimental prospects for observing processes which violate lepton number (Delta L) in four units ( or more). First, we reconsider neutrinoless quadruple beta decay, deriving a model independent and very conservative lower limit on its half- life of the order of 10(41) ys for Nd-150. This renders quadruple beta decay unobservable for any feasible experiment. We then turn to a more general discussion of different possible low-energy processes with values Delta L >= 4. A simple operator analysis leads to rather pessimistic conclusions about the observability at low-energy experiments in all cases we study. However, the situation looks much brighter for accelerator experiments. For two example models with Delta L = 4 and another one with Delta L = 5, we show how the LHC or a hypothetical future pp collider, such as the FCC, could probe multilepton number violating operators at the TeV scale.  
  Address [Fonseca, Renato M.; Hirsch, Martin] Univ Valencia, CSIC, Inst Fis Corpuscular, AHEP Grp, Spain Edificio Inst Paterna,Apartado 22085, E-46071 Valencia, Spain, Email: renato.fonseca@ific.uv.es;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000439791500005 Approved no  
  Is ISI yes International Collaboration (up) no  
  Call Number IFIC @ pastor @ Serial 3675  
Permanent link to this record
 
 
Author Cordero-Carrion, I.; Hirsch, M.; Vicente, A. url  doi
openurl 
  Title Master Majorana neutrino mass parametrization Type Journal Article
  Year 2019 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 99 Issue 7 Pages 075019 - 6pp  
  Keywords  
  Abstract After introducing a master formula for the Majorana neutrino mass matrix, we present a master parametrization for the Yukawa matrices automatically in agreement with neutrino oscillation data. This parametrization can be used for any model that induces Majorana neutrino masses. The application of the master parametrization is also illustrated in an example model, with special focus on its lepton flavor violating phenomenology.  
  Address [Cordero-Carrion, I.] Univ Valencia, Dept Matemat, E-46100 Valencia, Spain, Email: isabel.cordero@uv.es;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000464743100007 Approved no  
  Is ISI yes International Collaboration (up) no  
  Call Number IFIC @ pastor @ Serial 3981  
Permanent link to this record
 
 
Author Anamiati, G.; De Romeri, V.; Hirsch, M.; Ternes, C.A.; Tortola, M. url  doi
openurl 
  Title Quasi-Dirac neutrino oscillations at DUNE and JUNO Type Journal Article
  Year 2019 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 100 Issue 3 Pages 035032 - 12pp  
  Keywords  
  Abstract Quasi-Dirac neutrinos are obtained when the Lagrangian density of a neutrino mass model contains both Dirac and Majorana mass terms, and the Majorana terms are sufficiently small. This type of neutrino introduces new mixing angles and mass splittings into the Hamiltonian, which will modify the standard neutrino oscillation probabilities. In this paper, we focus on the case where the new mass splittings are too small to be measured, but new angles and phases are present. We perform a sensitivity study for this scenario for the upcoming experiments DUNE and JUNO, finding that they will improve current bounds on the relevant parameters. Finally, we also explore the discovery potential of both experiments, assuming that neutrinos are indeed quasi-Dirac particles.  
  Address [Anamiati, G.; De Romeri, V.; Hirsch, M.; Ternes, C. A.; Tortola, M.] Univ Valencia, CSIC, Inst Fis Corpuscular, Paterna 46980, Spain, Email: anamiati@ific.uv.es;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000482944200007 Approved no  
  Is ISI yes International Collaboration (up) no  
  Call Number IFIC @ pastor @ Serial 4124  
Permanent link to this record
 
 
Author Cordero-Carrion, I.; Hirsch, M.; Vicente, A. url  doi
openurl 
  Title General parametrization of Majorana neutrino mass models Type Journal Article
  Year 2020 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 101 Issue 7 Pages 075032 - 25pp  
  Keywords  
  Abstract We discuss a general formula which allows to automatically reproduce experimental data for Majorana neutrino mass models, while keeping the complete set of the remaining model parameters free for general scans, as necessary in order to provide reliable predictions for observables outside the neutrino sector. We provide a proof of this master parametrization and show how to apply it for several well-known neutrino mass models from the literature. We also discuss a list of special cases, in which the Yukawa couplings have to fulfill some particular additional conditions.  
  Address [Cordero-Carrion, I] Univ Valencia, Dept Matemat, E-46100 Valencia, Spain, Email: isabel.cordero@uv.es;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000527506300005 Approved no  
  Is ISI yes International Collaboration (up) no  
  Call Number IFIC @ pastor @ Serial 4377  
Permanent link to this record
 
 
Author Escribano, P.; Hirsch, M.; Nava, J.; Vicente, A. url  doi
openurl 
  Title Observable flavor violation from spontaneous lepton number breaking Type Journal Article
  Year 2022 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.  
  Volume 01 Issue 1 Pages 098 - 31pp  
  Keywords Beyond Standard Model; Neutrino Physics; Global Symmetries  
  Abstract We propose a simple model of spontaneous lepton number violation with potentially large flavor violating decays, including the possibility that majoron emitting decays, such as μ-> e J, saturate the experimental bounds. In this model the majoron is a singlet-doublet admixture. It generates a type-I seesaw for neutrino masses and contains also a vector-like lepton. As a by-product, the model can explain the anomalous (g – 2)(mu), in parts of its parameter space, where one expects that the branching ratio of the Higgs to muons is changed with respect to Standard Model expectations. However, the explanation of the muon g – 2 anomaly would lead to tension with recent astrophysical bounds on the majoron coupling to muons.  
  Address [Escribano, Pablo; Hirsch, Martin; Nava, Jacopo; Vicente, Avelino] Univ Valencia, Inst Fis Corpuscular, CSIC, Parc Cient Paterna,C Catedrcit Jose Beltrcin 2, E-46980 Valencia, Spain, Email: pablo.escribano@ifis.uv.es;  
  Corporate Author Thesis  
  Publisher Springer Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1029-8479 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000744514600003 Approved no  
  Is ISI yes International Collaboration (up) no  
  Call Number IFIC @ pastor @ Serial 5084  
Permanent link to this record
 
 
Author de Campos, F.; Eboli, O.J.P.; Hirsch, M.; Magro, M.B.; Porod, W.; Restrepo, D.; Valle, J.W.F. url  doi
openurl 
  Title Probing neutrino oscillations in supersymmetric models at the Large Hadron Collider Type Journal Article
  Year 2010 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 82 Issue 7 Pages 075002 - 8pp  
  Keywords  
  Abstract The lightest supersymmetric particle may decay with branching ratios that correlate with neutrino oscillation parameters. In this case the CERN Large Hadron Collider (LHC) has the potential to probe the atmospheric neutrino mixing angle with sensitivity competitive to its low-energy determination by underground experiments. Under realistic detection assumptions, we identify the necessary conditions for the experiments at CERN's LHC to probe the simplest scenario for neutrino masses induced by minimal supergravity with bilinear R parity violation.  
  Address [de Campos, F.] Univ Estadual Paulista, Dept Quim & Fis, Guaratingueta, SP, Brazil, Email: camposc@feg.unesp.br  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1550-7998 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000282570100004 Approved no  
  Is ISI yes International Collaboration (up) yes  
  Call Number IFIC @ elepoucu @ Serial 367  
Permanent link to this record
 
 
Author Esteves, J.N.; Romao, J.C.; Hirsch, M.; Staub, F.; Porod, W. url  doi
openurl 
  Title Supersymmetric type-III seesaw mechanism: Lepton flavor violating decays and dark matter Type Journal Article
  Year 2011 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 83 Issue 1 Pages 013003 - 21pp  
  Keywords  
  Abstract We study a supersymmetric version of the seesaw mechanism type III. The model consists of the minimal supersymmetric extension of the standard model particle content plus three copies of 24 superfields. The fermionic part of the SU(2) triplet contained in the 24 is responsible for the type-III seesaw, which is used to explain the observed neutrino masses and mixings. Complete copies of 24 are introduced to maintain gauge coupling unification. These additional states change the beta functions of the gauge couplings above the seesaw scale. Using minimal Supergravity boundary conditions, we calculate the resulting supersymmetric mass spectra at the electroweak scale using full 2-loop renormalization group equations. We show that the resulting spectrum can be quite different compared to the usual minimal Supergravity spectrum. We discuss how this might be used to obtain information on the seesaw scale from mass measurements. Constraints on the model space due to limits on lepton flavour violating decays are discussed. The main constraints come from the bounds on μ-> e gamma but there are also regions where the decay tau -> μgamma gives stronger constraints. We also calculate the regions allowed by the dark matter constraint. For the sake of completeness, we compare our results with those for the supersymmetric seesaw type II and, to some extent, with type I.  
  Address [Esteves, J. N.; Romao, J. C.] Inst Super Tecn, Dept Fis, P-1049001 Lisbon, Portugal, Email: joaomest@cftp.ist.utl.pt  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1550-7998 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000286765100002 Approved no  
  Is ISI yes International Collaboration (up) yes  
  Call Number IFIC @ pastor @ Serial 583  
Permanent link to this record
 
 
Author Esteves, J.N.; Romao, J.C.; Hirsch, M.; Vicente, A.; Porod, W.; Staub, F. url  doi
openurl 
  Title LHC and lepton flavour violation phenomenology of a left-right extension of the MSSM Type Journal Article
  Year 2010 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.  
  Volume 12 Issue 12 Pages 077 - 44pp  
  Keywords Supersymmetry Phenomenology  
  Abstract We study the phenomenology of a supersymmetric left-right model, assuming minimal supergravity boundary conditions. Both left-right and (B-L) symmetries are broken at an energy scale close to, but significantly below the GUT scale. Neutrino data is explained via a seesaw mechanism. We calculate the RGEs for superpotential and soft parameters complete at 2-loop order. At low energies lepton flavour violation (LFV) and small, but potentially measurable mass splittings in the charged scalar lepton sector appear, due to the RGE running. Different from the supersymmetric “pure seesaw” models, both, LFV and slepton mass splittings, occur not only in the left-but also in the right slepton sector. Especially, ratios of LFV slepton decays, such as Br((tau) over bar (R) -> μchi(0)(1))/Br((tau) over bar (L) -> μchi(0)(1)) are sensitive to the ratio of (B-L) and left-right symmetry breaking scales. Also the model predicts a polarization asymmetry of the outgoing positrons in the decay mu(+) -> e(+)gamma, A similar to [0, 1], which differs from the pure seesaw “prediction” A = 1. Observation of any of these signals allows to distinguish this model from any of the three standard, pure (mSugra) seesaw setups.  
  Address [Esteves, J. N.; Romao, J. C.] Inst Super Tecn, Dept Fis, P-1049001 Lisbon, Portugal, Email: joaomest@cftp.ist.utl.pt  
  Corporate Author Thesis  
  Publisher Springer Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1126-6708 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000285964200015 Approved no  
  Is ISI yes International Collaboration (up) yes  
  Call Number IFIC @ pastor @ Serial 532  
Permanent link to this record
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