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Author Cepedello, R.; Hirsch, M.; Helo, J.C. url  doi
openurl 
  Title Loop neutrino masses from d=7 operator Type Journal Article
  Year 2017 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.  
  Volume 07 Issue 7 Pages 079 - 21pp  
  Keywords Beyond Standard Model; Neutrino Physics  
  Abstract We discuss the generation of small neutrino masses from d = 71 -loop diagrams. We first systematically analyze all possible d = 7 1 -loop topologies. There is a total of 48 topologies, but only 8 of these can lead to “genuine” d = 7 neutrino masses. Here, we define genuine models to be models in which neither d = 5 nor d = 7 tree -level masses nor a d = 5 1 -loop mass appear, such that the d = 7 1 -loop is the leading order contribution to the neutrino masses. All genuine models can then be organized w.r.t. their particle content. We find there is only one diagram with no representation larger than triplet, while there are 22 diagrams with quadruplets. We briefly discuss three minimal example models of this kind.  
  Address [Cepedello, R.; Hirsch, M.] Univ Valencia, AHEP Grp, Inst Fis Corpuscular, CSIC, Edificio Inst Paterna,Apartado 22085, E-46071 Valencia, Spain, Email: ricepe@ific.uv.es;  
  Corporate Author Thesis  
  Publisher Springer Place of Publication Editor  
  Language English Summary Language Original Title (up)  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1029-8479 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000405916600003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3223  
Permanent link to this record
 

 
Author Cepedello, R.; Hirsch, M.; Helo, J.C. url  doi
openurl 
  Title Lepton number violating phenomenology of d=7 neutrino mass models Type Journal Article
  Year 2018 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.  
  Volume 01 Issue 1 Pages 009 - 24pp  
  Keywords Beyond Standard Model; Neutrino Physics  
  Abstract We study the phenomenology of d = 7 1-loop neutrino mass models. All models in this particular class require the existence of several new SU(2)(L) multiplets, both scalar and fermionic, and thus predict a rich phenomenology at the LHC. The observed neutrino masses and mixings can easily be fitted in these models. Interestingly, despite the smallness of the observed neutrino masses, some particular lepton number violating (LNV) final states can arise with observable branching ratios. These LNV final states consists of leptons and gauge bosons with high multiplicities, such as 4/ + 4W, 6/ + 2W etc. We study current constraints on these models from upper bounds on charged lepton flavour violating decays, existing lepton number conserving searches at the LHC and discuss possible future LNV searches.  
  Address [Cepedello, R.] Univ Valencia, CSIC, Inst Fis Corpuscular, AHEP Grp, Edificio Inst Paterna,Apartado 22085, E-46071 Valencia, Spain, Email: ricepe@ific.uv.es;  
  Corporate Author Thesis  
  Publisher Springer Place of Publication Editor  
  Language English Summary Language Original Title (up)  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1029-8479 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000419113900002 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3443  
Permanent link to this record
 

 
Author Cottin, G.; Helo, J.C.; Hirsch, M. url  doi
openurl 
  Title Searches for light sterile neutrinos with multitrack displaced vertices Type Journal Article
  Year 2018 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 97 Issue 5 Pages 055025 - 6pp  
  Keywords  
  Abstract We study discovery prospects for long-lived sterile neutrinos at the LHC with multitrack displaced vertices, with masses below the electroweak scale. We reinterpret current displaced vertex searches making use of publicly available, parametrized selection efficiencies for modeling the detector response to displaced vertices. We focus on the production of right-handed WR bosons and neutrinos N in a left-right symmetric model, and find poor sensitivity. After proposing a different trigger strategy ( considering the prompt lepton accompanying the neutrino displaced vertex) and optimized cuts in the invariant mass and track multiplicity of the vertex, we find that the LHC with root s = 13 TeV and 300 fb(-1) is able to probe sterile neutrino masses between 10 GeV < m(N) < 20 GeV ( for a right-handed gauge boson mass of 2 TeV < m(WR) < 3.5 TeV). To probe higher masses up to m(N) similar to 30 GeV and m(WR) < 5 TeV, 3000 fb(-1) will be needed. This work joins other efforts in motivating dedicated experimental searches to target this low sterile neutrino mass region.  
  Address [Cottin, Giovanna] Univ Cambridge, Cavendish Lab, Cambridge CB3 0HE, England, Email: gcottin@phys.ntu.edu.tw;  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title (up)  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000427640400005 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3526  
Permanent link to this record
 

 
Author Fonseca, R.M.; Hirsch, M.; Srivastava, R. url  doi
openurl 
  Title Delta L=3 processes: Proton decay and the LHC Type Journal Article
  Year 2018 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 97 Issue 7 Pages 075026 - 7pp  
  Keywords  
  Abstract We discuss lepton number violation in three units. From an effective field theory point of view, Delta L = 3 processes can only arise from dimension 9 or higher operators. These operators also violate baryon number, hence many of them will induce proton decay. Given the high dimensionality of these operators, in order to have a proton half-life in the observable range, the new physics associated to Delta L = 3 processes should be at a scale as low as 1 TeV. This opens up the possibility of searching for such processes not only in proton decay experiments but also at the LHC. In this work we analyze the relevant d = 9, 11, 13 operators which violate lepton number in three units. We then construct one simple concrete model with interesting low- and high-energy phenomenology.  
  Address [Fonseca, Renato M.; Hirsch, Martin; Srivastava, Rahul] Univ Valencia, CSIC, Inst Fis Corpuscular, AHEP Grp, Parc Cient Paterna,C Catedrat Jose Beltran 2, E-46980 Paterna, 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 (up)  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000430459800005 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 3560  
Permanent link to this record
 

 
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 (up)  
  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 no  
  Call Number IFIC @ pastor @ Serial 3581  
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