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Author Cottin, G.; Helo, J.C.; Hirsch, M.; Titov, A.; Wang, Z.S.
Title (down) Heavy neutral leptons in effective field theory and the high-luminosity LHC Type Journal Article
Year 2021 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.
Volume 09 Issue 9 Pages 039 - 34pp
Keywords Beyond Standard Model; Effective Field Theories; Neutrino Physics
Abstract Heavy neutral leptons (HNLs) with masses around the electroweak scale are expected to be rather long-lived particles, as a result of the observed smallness of the active neutrino masses. In this work, we study long-lived HNLs in NRSMEFT, a Standard Model (SM) extension with singlet fermions to which we add non-renormalizable operators up to dimension-6. Operators which contain two HNLs can lead to a sizable enhancement of the production cross sections, compared to the minimal case where HNLs are produced only via their mixing with the SM neutrinos. We calculate the expected sensitivities for the ATLAS detector and the future far-detector experiments: AL3X, ANUBIS, CODEX-b, FASER, MATHUSLA, and MoEDAL-MAPP in this setup. The sensitive ranges of the HNL mass and of the active-heavy mixing angle are much larger than those in the minimal case. We study both, Dirac and Majorana, HNLs and discuss how the two cases actually differ phenomenologically, for HNL masses above roughly 100 GeV.
Address [Cottin, Giovanna] Univ Adolfo Ibanez, Fac Artes Liberales, Dept Ciencias, Diagonal Las Torres 2640, Santiago, Chile, Email: giovanna.cottin@uai.cl;
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:000694840800001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4970
Permanent link to this record
 

 
Author Helo, J.C.; Hirsch, M.; Wang, Z.S.
Title (down) Heavy neutral fermions at the high-luminosity LHC Type Journal Article
Year 2018 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.
Volume 07 Issue 7 Pages 056 - 23pp
Keywords Beyond Standard Model; Neutrino Physics; Supersymmetric Standard Model
Abstract Long-lived light particles (LLLPs) appear in many extensions of the standard model. LLLPs are usually motivated by the observed small neutrino masses, by dark matter or both. Typical examples for fermionic LLLPs (a.k.a. heavy neutral fermions, HNFs) are sterile neutrinos or the lightest neutralino in R-parity violating supersymmetry. The high luminosity LHC is expected to deliver up to 3/ab of data. Searches for LLLPs in dedicated experiments at the LHC could then probe the parameter space of LLLP models with unprecedented sensitivity. Here, we compare the prospects of several recent experimental proposals, FASER, CODEX-b and MATHUSLA, to search for HNFs and discuss their relative merits.s
Address [Helo, Juan Carlos] Univ La Serena, Fac Ciencias, Dept Fis, Ave Cisternas 1200, La Serena, Chile, Email: jchelo@userena.cl;
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:000438141500008 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 3656
Permanent link to this record
 

 
Author Carquin, E.; Neill, N.A.; Helo, J.C.; Hirsch, M.
Title (down) Exotic colored fermions and lepton number violation at the LHC Type Journal Article
Year 2019 Publication Physical Review D Abbreviated Journal Phys. Rev. D
Volume 99 Issue 11 Pages 115028 - 9pp
Keywords
Abstract Majorana neutrino mass models with a scale of lepton number violation of order tem-electron-volts potentially lead to signals at the LHC. Here, we consider an extension of the standard model with a colored octet fermion and a scalar leptoquark. This model generates neutrino masses at two-loop order. We make a detailed Monte Carlo study of the lepton number violating signal at the LHC in this model, including a simulation of standard model backgrounds. Our forecast predicts that the LHC with 300/fb should be able to probe this model up to color-octet fermion masses in the range of (2.6-2.7) TeV, depending on the lepton flavor of the final state.
Address [Carquin, E.; Neill, N. A.] Univ Tecn Federico Santa Maria, Dept Fis, Casilla 110-V, Valparaiso, Chile, Email: edson.carquin@usm.cl;
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:000473024800004 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 4068
Permanent link to this record
 

 
Author Helo, J.C.; Hirsch, M.; Ota, T.; Pereira dos Santos, F.A.
Title (down) Double beta decay and neutrino mass models Type Journal Article
Year 2015 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.
Volume 05 Issue 5 Pages 092 - 40pp
Keywords Beyond Standard Model; Neutrino Physics
Abstract Neutrinoless double beta decay allows to constrain lepton number violating extensions of the standard model. If neutrinos are Majorana particles, the mass mechanism will always contribute to the decay rate, however, it is not a priori guaranteed to be the dominant contribution in all models. Here, we discuss whether the mass mechanism dominates or not from the theory point of view. We classify all possible (scalar-mediated) short-range contributions to the decay rate according to the loop level, at which the corresponding models will generate Majorana neutrino masses, and discuss the expected relative size of the different contributions to the decay rate in each class. Our discussion is general for models based on the SM group but does not cover models with an extended gauge. We also work out the phenomenology of one concrete 2-loop model in which both, mass mechanism and short-range diagram, might lead to competitive contributions, in some detail.
Address [Helo, J. C.] Univ Tecn Federico Santa Maria, Ctr Cient Tecnol Valparaiso, Valparaiso, Chile, Email: juancarlos.helo@usm.cl;
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:000363471700001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 2441
Permanent link to this record
 

 
Author Cottin, G.; Helo, J.C.; Hirsch, M.
Title (down) Displaced vertices as probes of sterile neutrino mixing at the LHC Type Journal Article
Year 2018 Publication Physical Review D Abbreviated Journal Phys. Rev. D
Volume 98 Issue 3 Pages 035012 - 6pp
Keywords
Abstract We investigate the reach at the LHC to probe light sterile neutrinos with displaced vertices. We focus on sterile neutrinos N with masses m(N) similar to (5-30) GeV that are produced in rare decays of the standard model gauge bosons and decay inside the inner trackers of the LHC detectors. With a strategy that triggers on the prompt lepton accompanying the N displaced vertex and considers charged tracks associated with it, we show that the 13 TeV LHC with 3000/fb is able to probe active-sterile neutrino mixings down to vertical bar V-lN vertical bar(2) approximate to 10(-9), with l = e, mu, which is an improvement of up to 4 orders of magnitude when comparing with current experimental limits from trileptons and proposed lepton-jets searches. In the case when tau mixing is present, mixing angles as low as vertical bar V-tau N vertical bar(2) approximate to 10(-8) can be accessed.
Address [Cottin, Giovanna] Natl Taiwan Univ, Dept Phys, Taipei 10617, Taiwan, Email: gcottin@phys.ntu.edu.tw;
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:000441109800001 Approved no
Is ISI yes International Collaboration yes
Call Number IFIC @ pastor @ Serial 3684
Permanent link to this record