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Author Hernandez, P.; Kekic, M.; Lopez-Pavon, J. url  doi
openurl 
  Title (up) Low-scale seesaw models versus N-eff Type Journal Article
  Year 2014 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 89 Issue 7 Pages 073009 - 7pp  
  Keywords  
  Abstract We consider the contribution of the extra sterile states in generic low-scale seesaw models to extra radiation, parametrized by N-eff. We find that the value of Neff is roughly independent of the seesaw scale within a wide range. We explore the full parameter space in the case of two extra sterile states and find that these models are strongly constrained by cosmological data for any value of the seesaw scale below O(100 MeV).  
  Address [Hernandez, P.; Kekic, M.] IFIC CSIC UVEG, E-46071 Valencia, Spain  
  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 WOS:000334317200005 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1754  
Permanent link to this record
 
 
Author Donini, A.; Hernandez, P.; Lopez-Pavon, J.; Maltoni, M. url  doi
openurl 
  Title (up) Minimal models with light sterile neutrinos Type Journal Article
  Year 2011 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.  
  Volume 07 Issue 7 Pages 105  
  Keywords  
  Abstract We study the constraints imposed by neutrino oscillation experiments on the minimal extensions of the Standard Model (SM) with n(R) gauge singlet fermions (“right-handed neutrinos”), that can account for neutrino masses. We consider the most general coupling of the new fields to the SM fields, in particular those that break lepton number and we do not assume any a priori hierarchy in the mass parameters. We proceed to analyze these models starting from the lowest level of complexity, defined by the number of extra fermionic degrees of freedom. The simplest choice that has enough free parameters in principle (i.e. two mass differences and two angles) to explain the confirmed solar and atmospheric oscillations corresponds to n(R) = 1. This minimal choice is shown to be excluded by data. The next-to-minimal choice corresponds to n(R) = 2. We perform a systematic study of the full parameter space in the limit of degenerate Majorana masses by requiring that at least two neutrino mass differences correspond to those established by solar and atmospheric oscillations. We identify several types of spectra that can fit long-baseline reactor and accelerator neutrino oscillation data, but fail in explaining solar and/or atmospheric data. The only two solutions that survive are the expected seesaw and quasi-Dirac regions, for which we set lower and upper bounds respectively on the Majorana mass scale. Solar data from neutral current measurements provide essential information to constrain the quasi-Dirac region. The possibility to accommodate the LSND/MiniBoone and reactor anomalies, and the implications for neutrinoless double-beta decay and tritium beta decay are briefly discussed.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language 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 WOS:000293741500041 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ elepoucu @ Serial 760  
Permanent link to this record
 
 
Author Linster, M.; Lopez-Pavon, J.; Ziegler, R. url  doi
openurl 
  Title (up) Neutrino observables from a U(2) flavor symmetry Type Journal Article
  Year 2021 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 103 Issue 1 Pages 015020 - 9pp  
  Keywords  
  Abstract We study the predictions for CP phases and absolute neutrino mass scale for broad classes of models with a U(2)-like flavor symmetry. For this purpose we consider the same special textures in neutrino and charged lepton mass matrices that are successful in the quark sector. While in the neutrino sector the U(2) structure enforces two texture zeros, the contribution of the charged lepton sector to the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrix can be parametrized by two rotation angles. Restricting to the cases where at least one of these angles is small, we obtain three representative scenarios. In all scenarios we obtain a narrow prediction for the sum of neutrino masses in the range of 60-75 meV, possibly in the reach of upcoming galaxy survey experiments. All scenarios can be excluded if near-future experimental date provide evidence for either neutrinoless double-beta decay or inverted neutrino mass ordering.  
  Address [Linster, Matthias; Ziegler, Robert] Karlsruhe Inst Technol, Inst Theoret Teilchenphys, D-76131 Karlsruhe, Germany  
  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:000609014300006 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4689  
Permanent link to this record
 
 
Author Drewes, M.; Klaric, J.; Lopez-Pavon, J. url  doi
openurl 
  Title (up) New benchmark models for heavy neutral lepton searches Type Journal Article
  Year 2022 Publication European Physical Journal C Abbreviated Journal Eur. Phys. J. C  
  Volume 82 Issue 12 Pages 1176 - 11pp  
  Keywords  
  Abstract The sensitivity of direct searches for heavy neutral leptons (HNLs) in accelerator-based experiments depends strongly on the particles properties. Commonly used benchmark scenarios are important to ensure comparability and consistency between experimental searches, re-interpretations, and sensitivity studies for different facilities. In models where the HNLs are primarily produced and decay through the weak interaction, benchmarks are in particular defined by fixing the relative strengths of their mixing with SM neutrinos of different flavours, and the interpretation of experimental data is known to strongly depend on those ratios. The commonly used benchmarks in which a single HNL flavour exclusively interacts with one Standard Model generation do not reflect what is found in realistic neutrino mass models. We identify two additional benchmarks for accelerator-based direct HNL searches, which we primarily select based on the requirement to provide a better approximation for the phenomenology of realistic neutrino mass models in view of present and future neutrino oscillation data.  
  Address [Drewes, M.; Klaric, J.] Catholic Univ Louvain, Ctr Cosmol Particle Phys & Phenomenol, B-1348 Louvain La Neuve, Belgium, Email: marco.drewes@uclouvain.be;  
  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 1434-6044 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000906204200001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5446  
Permanent link to this record
 
 
Author Coloma, P.; Lopez-Pavon, J.; Rosauro-Alcaraz, S.; Urrea, S. url  doi
openurl 
  Title (up) New physics from oscillations at the DUNE near detector, and the role of systematic uncertainties Type Journal Article
  Year 2021 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.  
  Volume 08 Issue 8 Pages 065 - 33pp  
  Keywords Beyond Standard Model; Neutrino Physics  
  Abstract We study the capabilities of the DUNE near detector to probe deviations from unitarity of the leptonic mixing matrix, the 3+1 sterile formalism and Non-Standard Interactions affecting neutrino production and detection. We clarify the relation and possible mappings among the three formalisms at short-baseline experiments, and we add to current analyses in the literature the study of the nu(mu)-> nu(tau) appearance channel. We study in detail the impact of spectral uncertainties on the sensitivity to new physics using the DUNE near detector, which has been widely overlooked in the literature. Our analysis shows that this plays an important role on the results and, in particular, that it can lead to a strong reduction in the sensitivity to sterile neutrinos from nu(mu)-> nu(e) transitions, by more than two orders of magnitude. This stresses the importance of a joint experimental and theoretical effort to improve our understanding of neutrino nucleus cross sections, as well as hadron production uncertainties and beam focusing effects. Nevertheless, even with our conservative and more realistic implementation of systematic uncertainties, we find that an improvement over current bounds in the new physics frameworks considered is generally expected if spectral uncertainties are below the 5% level.  
  Address [Coloma, Pilar; Rosauro-Alcaraz, Salvador] Univ Autonoma Madrid, Inst Fis Teor, UAM CSIC, Calle Nicolas Cabrera 13-15, E-28049 Madrid, Spain, Email: pilar.coloma@ift.csic.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:000686712300001 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 4944  
Permanent link to this record
 
 
Author Coloma, P.; Donini, A.; Lopez-Pavon, J.; Minakata, H. url  doi
openurl 
  Title (up) Non-standard interactions at a neutrino factory: correlations and CP violation Type Journal Article
  Year 2011 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.  
  Volume 08 Issue 8 Pages 036 - 41pp  
  Keywords Beyond Standard Model; Neutrino Physics  
  Abstract We explore the potential of several Neutrino Factory (NF) setups to constrain, discover and measure new physics effects due to Non-Standard Interactions (NSI) in propagation through Earth matter. We first study the impact of NSI in the measurement of theta(13): we find that these could be large due to strong correlations of theta(13) with NSI parameters in the golden channel, and the inclusion of a detector at the magic baseline is crucial in order to reduce them as much as possible. We present, then, the sensitivity of the considered NF setups to the NSI parameters, paying special attention to correlations arising between them and the standard oscillation parameters, when all NSI parameters are introduced at once. Off-diagonal NSI parameters could be tested down to the level of 10(-3), whereas the diagonal combinations (epsilon(ee) – epsilon(tau tau)) and (epsilon(mu mu) – epsilon(tau tau)) can be tested down to 10(-1) and 10(-2), respectively. The possibilities of observing CP violation in this context are also explored, by presenting a first scan of the CP discovery potential of the NF setups to the phases phi(e mu), phi(e tau) and delta. We study separately the case where CP violation comes only from non-standard sources, and the case where it is entangled with the standard source, delta. In case delta turns out to be CP conserving, the interesting possibility of observing CP violation for reasonably small values of the NSI parameters emerges.  
  Address [Coloma, P] Univ Autonoma Madrid, Dept Fis Teor, E-28049 Madrid, Spain, Email: p.coloma@uam.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 1126-6708 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000294901400046 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ elepoucu @ Serial 772  
Permanent link to this record
 
 
Author Fernandez-Martinez, E.; Lopez-Pavon, J.; Ota, T.; Rosauro-Alcaraz, S. url  doi
openurl 
  Title (up) nu electroweak baryogenesis Type Journal Article
  Year 2020 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.  
  Volume 10 Issue 10 Pages 063 - 28pp  
  Keywords Beyond Standard Model; Cosmology of Theories beyond the SM; CP viola- tion; Neutrino Physics  
  Abstract We investigate if the CP violation necessary for successful electroweak baryo- genesis may be sourced by the neutrino Yukawa couplings. In particular, we consider an electroweak scale Seesaw realization with sizable Yukawas where the new neutrino singlets form (pseudo)-Dirac pairs, as in the linear or inverse Seesaw variants. We find that the baryon asymmetry obtained strongly depends on how the neutrino masses vary within the bubble walls. Moreover, we also find that flavour effects critically impact the final asymmetry obtained and that, taking them into account, the observed value may be obtained in some regions of the parameter space. This source of CP violation naturally avoids the strong constraints from electric dipole moments and links the origin of the baryon asymmetry of the Universe with the mechanism underlying neutrino masses. Interestingly, the mixing of the active and heavy neutrinos needs to be sizable and could be probed at the LHC or future collider experiments.  
  Address [Fernandez-Martinez, E.; Ota, T.; Rosauro-Alcaraz, S.] Univ Autonoma Madrid, Dept Fis Teor, IFT UAM CSIC, Madrid 28049, Spain, Email: enrique.fernandez-martinez@uam.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:000582727900001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4582  
Permanent link to this record
 
 
Author Fernandez-Martinez, E.; Lopez-Pavon, J.; No, J.M.; Ota, T.; Rosauro-Alcaraz, S. url  doi
openurl 
  Title (up) nu Electroweak baryogenesis: the scalar singlet strikes back Type Journal Article
  Year 2023 Publication European Physical Journal C Abbreviated Journal Eur. Phys. J. C  
  Volume 83 Issue 8 Pages 715 - 23pp  
  Keywords  
  Abstract We perform a comprehensive scan of the parameter space of a general singlet scalar extension of the Standard Model to identify the regions which can lead to a strong first-order phase transition, as required by the electroweak baryogenesis mechanism. We find that taking into account bubble nucleation is a fundamental constraint on the parameter space and present a conservative and fast estimate for it so as to enable efficient parameter space scanning. The allowed regions turn out to be already significantly probed by constraints on the scalar mixing from Higgs signal strength measurements. We also consider the addition of new neutrino singlet fields with Yukawa couplings to both scalars and forming heavy (pseudo)-Dirac pairs, as in the linear or inverse Seesaw mechanisms for neutrino mass generation. We find that their inclusion does not alter the allowed parameter space from early universe phenomenology in a significant way. Conversely, there are allowed regions of the parameter space where the presence of the neutrino singlets would remarkably modify the collider phenomenology, yielding interesting new signatures in Higgs and singlet scalar decays.  
  Address [Fernandez-Martinez, E.; No, J. M.; Ota, T.] Univ Autonoma Madrid, CSIC, Dept Fis Teor, IFT UAM, Madrid 28049, Spain, Email: rosauro@ijclab.in2p3.fr  
  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 1434-6044 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:001045200700003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5609  
Permanent link to this record
 
 
Author Hernandez, P.; Kekic, M.; Lopez-Pavon, J. url  doi
openurl 
  Title (up) N_eff in low-scale seesaw models versus the lightest neutrino mass Type Journal Article
  Year 2014 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 90 Issue 6 Pages 065033 - 12pp  
  Keywords  
  Abstract We evaluate the contribution to N_eff of the extra sterile states in low-scale type I seesaw models (with three extra sterile states). We explore the full parameter space and find that at least two of the heavy states always reach thermalization in the early Universe, while the third one might not thermalize provided the lightest neutrino mass is below O(10(-3) eV). Constraints from cosmology therefore severely restrict the spectra of heavy states in the range 1 eV-100 MeV. The implications for neutrinoless double beta decay are also discussed.  
  Address [Hernandez, P.; Kekic, M.] Univ Valencia, IFIC CSIC, E-46071 Valencia, Spain, Email: m.pilar.hernandez@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 1550-7998 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000344108100004 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 2001  
Permanent link to this record
 
 
Author Sandner, S.; Hernandez, P.; Lopez-Pavon, J.; Rius, N. url  doi
openurl 
  Title (up) Predicting the baryon asymmetry with degenerate right-handed neutrinos Type Journal Article
  Year 2023 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.  
  Volume 11 Issue 11 Pages 153 - 37pp  
  Keywords Baryo-and Leptogenesis; Sterile or Heavy Neutrinos; Early Universe Particle Physics  
  Abstract We consider the generation of a baryon asymmetry in an extension of the Standard Model with two singlet Majorana fermions that are degenerate above the electroweak phase transition. The model can explain neutrino masses as well as the observed matter-antimatter asymmetry, for masses of the heavy singlets below the electroweak scale. The only physical CP violating phases in the model are those in the PMNS mixing matrix, i.e. the Dirac phase and a Majorana phase that enter light neutrino observables. We present an accurate analytic approximation for the baryon asymmetry in terms of CP flavour invariants, and derive the correlations with neutrino observables. We demonstrate that the measurement of CP violation in neutrino oscillations as well as the mixings of the heavy neutral leptons with the electron, muon and tau flavours suffice to pin down the matter-antimatter asymmetry from laboratory measurements.  
  Address [Sandner, S.] Univ Valencia, Inst Fis Corpuscular, Edificio Inst Invest,Catedrat Jose Beltran 2, Paterna 46980, Spain, Email: stefan.sandner@ific.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:001111979900002 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 5869  
Permanent link to this record
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