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Author Esteves, J.N.; Joaquim, F.R.; Joshipura, A.S.; Romao, J.C.; Tortola, M.; Valle, J.W.F. url  doi
openurl 
  Title A(4)-based neutrino masses with Majoron decaying dark matter Type Journal Article
  Year 2010 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 82 Issue 7 Pages 073008 - 8pp  
  Keywords (up)  
  Abstract We propose an A(4) flavor-symmetric SU(3) circle times SU(2) circle times U(1) seesaw model where lepton number is broken spontaneously. A consistent two-zero texture pattern of neutrino masses and mixing emerges from the interplay of type-I and type-II seesaw contributions, with important phenomenological predictions. We show that, if the Majoron becomes massive, such seesaw scenario provides a viable candidate for decaying dark matter, consistent with cosmic microwave background lifetime constraints that follow from current WMAP observations. We also calculate the subleading one-loop-induced decay into photons which leads to a monoenergetic emission line that may be observed in future x-ray missions such as Xenia.  
  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:000282812200004 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ elepoucu @ Serial 360  
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 (up)  
  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 yes  
  Call Number IFIC @ pastor @ Serial 583  
Permanent link to this record
 

 
Author Arbelaez, C.; Fonseca, R.M.; Romao, J.C.; Hirsch, M. url  doi
openurl 
  Title Supersymmetric SO(10)-inspired GUTs with sliding scales Type Journal Article
  Year 2013 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 87 Issue 7 Pages 075010 - 19pp  
  Keywords (up)  
  Abstract We construct lists of supersymmetric models with extended gauge groups at intermediate steps, all of which are inspired by SO(10) unification. We consider three different kinds of setups: (i) the model has exactly one additional intermediate scale with a left-right (LR) symmetric group; (ii) SO(10) is broken to the LR group via an intermediate Pati-Salam scale; and (iii) the LR group is broken into SU(3)(c) X SU(2)(L) X U(1)(R) X U(1)(B-L), before breaking to the standard model (SM) group. We use sets of conditions, which we call the “sliding mechanism,” which yield unification with the extended gauge group(s) allowed at arbitrary intermediate energy scales. All models thus can have new gauge bosons within the reach of the LHC, in principle. We apply additional conditions, such as perturbative unification, renormalizability and anomaly cancellation and find that, despite these requirements, for the ansatz (i) with only one additional scale still around 50 different variants exist that can have a LR symmetry below 10 TeV. For the more complicated schemes (ii) and (iii) literally thousands of possible variants exist, and for scheme (ii) we have also found variants with very low Pati-Salam scales. We also discuss possible experimental tests of the models from measurements of supersymmetry masses. Assuming mSugra boundary conditions we calculate certain combinations of soft terms, called “invariants,” for the different classes of models. Values for all the invariants can be classified into a small number of sets, which contain information about the class of models and, in principle, the scale of beyond-minimal supersymmetric extension of the Standard Model physics, even in case the extended gauge group is broken at an energy beyond the reach of the LHC.  
  Address Univ Tecn Lisboa, Dept Fis, P-1049001 Lisbon, Portugal, Email: Carolina.Arbelaez@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 WOS:000317586900007 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1401  
Permanent link to this record
 

 
Author Forero, D.V.; Morisi, S.; Romao, J.C.; Valle, J.W.F. url  doi
openurl 
  Title Neutrino mixing with revamped A(4) flavor symmetry Type Journal Article
  Year 2013 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 88 Issue 1 Pages 016003 - 7pp  
  Keywords (up)  
  Abstract We suggest a minimal extension of the simplest A(4) flavor model that can induce a nonzero theta(13) value, as required by recent neutrino oscillation data from reactors and accelerators. The predicted correlation between the atmospheric mixing angle theta(23) and the magnitude of theta(13) leads to an allowed region substantially smaller than indicated by neutrino-oscillation global fits. Moreover, the scheme correlates CP violation in neutrino oscillations with the octant of the atmospheric mixing parameter theta(23) in such a way that, for example, maximal mixing necessarily violates CP. We briefly comment on other phenomenological features of the model.  
  Address [Forero, D. V.; Romao, J. C.] Univ Tecn Lisboa, Dept Fis, Inst Super Tecn, P-1049001 Lisbon, Portugal, Email: dvanegas@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 1550-7998 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000321125000011 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1507  
Permanent link to this record
 

 
Author Arbelaez, C.; Romao, J.C.; Hirsch, M.; Malinsky, M. url  doi
openurl 
  Title LHC-scale left-right symmetry and unification Type Journal Article
  Year 2014 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 89 Issue 3 Pages 035002 - 19pp  
  Keywords (up)  
  Abstract We construct a comprehensive list of nonsupersymmetric standard model extensions with a low-scale left-right (LR)-symmetric intermediate stage that may be obtained as simple low-energy effective theories within a class of renormalizable SO(10) grand unified theories. Unlike the traditional “minimal” LR models many of our example settings support a perfect gauge coupling unification even if the LR scale is in the LHC domain at a price of only (a few copies of) one or two types of extra fields pulled down to the TeV-scale ballpark. We discuss the main aspects of a potentially realistic model building conforming the basic constraints from the quark and lepton sector flavor structure, proton decay limits, etc. We pay special attention to the theoretical uncertainties related to the limited information about the underlying unified framework in the bottom-up approach, in particular, to their role in the possible extraction of the LR-breaking scale. We observe a general tendency for the models without new colored states in the TeV domain to be on the verge of incompatibility with the proton stability constraints.  
  Address [Arbelaez, Carolina; Romao, Jorge C.] Univ Lisbon, Inst Super Tecn, Dept Fis, P-1049001 Lisbon, Portugal, Email: carolina@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 1550-7998 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000331878400006 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1703  
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