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Author Cottin, G.; Helo, J.C.; Hirsch, M. url  doi
openurl 
  Title (up) 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
 

 
Author Helo, J.C.; Hirsch, M.; Ota, T.; Pereira dos Santos, F.A. url  doi
openurl 
  Title (up) 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 Hirsch, M.; Staub, F.; Vicente, A. url  doi
openurl 
  Title (up) Enhancing l(i) -> 3l(j) with the Z(0)-penguin Type Journal Article
  Year 2012 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 85 Issue 11 Pages 113013 - 5pp  
  Keywords  
  Abstract Lepton flavor violation has been observed in neutrino oscillations. For charged lepton flavor violation decays only upper limits are known, but sizable branching ratios are expected in many neutrino mass models. High-scale models, such as the classical supersymmetric seesaw, usually predict that decays l(i) -> 3l(j) are roughly a factor alpha smaller than the corresponding decays l(i) -> l(j)gamma. Here we demonstrate that the Z(0)-penguin diagram can give an enhancement for decays l(i) -> 3l(j) in many extensions of the minimal supersymmetric standard model (MSSM). We first discuss why the Z(0)-penguin is not dominant in the MSSM with seesaw and show that much larger contributions from the Z(0)-penguin are expected in general. We then demonstrate the effect numerically in two example models, namely, the supersymmetric inverse seesaw and R-parity violating supersymmetry.  
  Address [Hirsch, M.] Univ Valencia Edificio Inst Paterna, CSIC, AHEP Grp, Inst Fis Corpuscular, E-46071 Valencia, Spain, Email: mahirsch@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:000305680800003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1075  
Permanent link to this record
 

 
Author Carquin, E.; Neill, N.A.; Helo, J.C.; Hirsch, M. url  doi
openurl 
  Title (up) 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 Cepedello, R.; Esser, F.; Hirsch, M.; Sanz, V. url  doi
openurl 
  Title (up) Faking ZZZ vertices at the LHC Type Journal Article
  Year 2024 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.  
  Volume 12 Issue 12 Pages 098 - 20pp  
  Keywords SMEFT; Specific BSM Phenomenology  
  Abstract Searches for anomalous neutral triple gauge boson couplings (NTGCs) provide important tests for the gauge structure of the standard model. At the LHC, NTGCs are searched for via the process pp -> ZZ -> 4l, where the two Z-bosons are on-shell. In this paper, we discuss how the same process can occur through tree-level diagrams just adding a vector-like quark (VLQ) to the standard model. Since NTGCs are generated in standard model effective theory (SMEFT) only at 1-loop order, vector like quarks could be an important alternative interpretation to, and background for, NTGC searches. Here, we construct a simple example model, discuss low-energy constraints and estimate current and future sensitivities on the model parameters from pp -> ZZ -> 4l searches.  
  Address [Cepedello, Ricardo] Univ Granada, Dept Fis Teor & Cosmos, Campus Fuentenueva, E-18071 Granada, Spain, Email: ricepe@ugr.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:001376065200003 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 6371  
Permanent link to this record
 

 
Author Deppisch, F.F.; Harz, J.; Huang, W.C.; Hirsch, M.; Pas, H. url  doi
openurl 
  Title (up) Falsifying high-scale baryogenesis with neutrinoless double beta decay and lepton flavor violation Type Journal Article
  Year 2015 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 92 Issue 3 Pages 036005 - 6pp  
  Keywords  
  Abstract Interactions that manifest themselves as lepton number violating processes at low energies in combination with sphaleron transitions typically erase any preexisting baryon asymmetry of the Universe. In this article, we discuss the constraints obtained from an observation of neutrinoless double beta decay in this context. If a new physics mechanism of neutrinoless double beta decay other than the standard light neutrino exchange is observed, typical scenarios of high-scale baryogenesis will be excluded unless the baryon asymmetry is stabilized via some new mechanism. We also sketch how this conclusion can be extended beyond the first lepton generation by incorporating lepton flavor violating processes.  
  Address [Deppisch, Frank F.; Harz, Julia; Huang, Wei-Chih] UCL, Dept Phys & Astron, London WC1E 6BT, England, Email: f.deppisch@ucl.ac.uk;  
  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:000359050900003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 2318  
Permanent link to this record
 

 
Author Deppisch, F.F.; Harz, J.; Hirsch, M. url  doi
openurl 
  Title (up) Falsifying High-Scale Leptogenesis at the LHC Type Journal Article
  Year 2014 Publication Physical Review Letters Abbreviated Journal Phys. Rev. Lett.  
  Volume 112 Issue 22 Pages 221601 - 5pp  
  Keywords  
  Abstract Measuring a nonzero value for the cross section of any lepton number violating (LNV) process would put a strong lower limit on the washout factor for the effective lepton number density in the early Universe at times close to the electroweak phase transition and thus would lead to important constraints on any high-scale model for the generation of the observed baryon asymmetry based on LNV. In particular, for leptogenesis (LG) models with masses of the right-handed neutrinos heavier than the mass scale observed at the LHC, the implied large washout factors would lead to a violation of the out-of-equilibrium condition and exponentially suppress the net lepton number produced in such LG models. We thus demonstrate that the observation of LNV processes at the LHC results in the falsification of high-scale LG models. However, no conclusions about the viability of LG models can be drawn from the nonobservation of LNV processes.  
  Address [Deppisch, Frank F.; Harz, Julia] UCL, Dept Phys & Astron, London WC1E 6BT, England, Email: f.deppisch@ucl.ac.uk;  
  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 0031-9007 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000336920800003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1816  
Permanent link to this record
 

 
Author Arbelaez, C.; Hirsch, M.; Restrepo, D. url  doi
openurl 
  Title (up) Fermionic triplet dark matter in an SO(10)-inspired left-right model Type Journal Article
  Year 2017 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 95 Issue 9 Pages 095034 - 9pp  
  Keywords  
  Abstract We study a left right (LR) extension of the Standard Model (SM) where the Dark Matter(DM) candidate is composed of a set of fermionic Majorana triplets. The DM is stabilized by a remnant Z(2) symmetry from the breaking of the LR group to the SM. Two simple scenarios where the DM particles plus a certain set of extra fields lead to gauge coupling unification with a low LR scale are explored. The constraints from relic density and predictions for direct detection are discussed for both scenarios. The first scenario with a SUd(2)(R) vectorlike fermion triplet contains a DM candidate which is almost unconstrained by current direct detection experiments. The second scenario, with an additional SU(2)R triplet, opens up a scalar portal leading to direct detection constraints which are similar to collider limits for right gauge bosons. The DM parameter space consistent with phenomenological requirements can also lead to successful gauge coupling unification in a SO(10) setup.  
  Address [Arbelaez, Carolina] Univ Tecn Federico Santa Maria, Casilla 110-5, Valparaiso, Chile, Email: carolina.arbelaez@.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:000402471800010 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3154  
Permanent link to this record
 

 
Author Cepedello, R.; Esser, F.; Hirsch, M.; Sanz, V. url  doi
openurl 
  Title (up) Fermionic UV models for neutral triple gauge boson vertices Type Journal Article
  Year 2024 Publication Journal of High Energy Physics Abbreviated Journal J. High Energy Phys.  
  Volume 07 Issue 7 Pages 275 - 28pp  
  Keywords Effective Field Theories; SMEFT; Specific BSM Phenomenology; Vector-Like Fermions  
  Abstract Searches for anomalous neutral triple gauge boson couplings (NTGCs) provide important tests for the gauge structure of the standard model. In SMEFT (“standard model effective field theory”) NTGCs appear only at the level of dimension-8 operators. While the phenomenology of these operators has been discussed extensively in the literature, renormalizable UV models that can generate these operators are scarce. In this work, we study a variety of extensions of the SM with heavy fermions and calculate their matching to d = 8 NTGC operators. We point out that the complete matching of UV models requires four different CP-conserving d = 8 operators and that the single CPC d = 8 operator, most commonly used by the experimental collaborations, does not describe all possible NTGC form factors. Despite stringent experimental constraints on NTGCs, limits on the scale of UV models are relatively weak, because their contributions are doubly suppressed (being d = 8 and 1-loop). We suggest a series of benchmark UV scenarios suitable for interpreting searches for NTGCs in the upcoming LHC runs, obtain their current limits and provide estimates for the expected sensitivity of the high-luminosity LHC.  
  Address [Cepedello, Ricardo] Univ Granada, Dept Fis Teor & Cosmos, Campus Fuentenueva, E-18071 Granada, Spain, Email: ricepe@ugr.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:001282227200003 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 6222  
Permanent link to this record
 

 
Author Adolf, P.; Hirsch, M.; Krieg, S.; Pas, H.; Tabet, M. url  doi
openurl 
  Title (up) Fitting the DESI BAO data with dark energy driven by the Cohen-Kaplan-Nelson bound Type Journal Article
  Year 2024 Publication Journal of Cosmology and Astroparticle Physics Abbreviated Journal J. Cosmol. Astropart. Phys.  
  Volume 08 Issue 8 Pages 048 - 18pp  
  Keywords dark energy theory; dark energy experiments; Frequentist statistics; baryon acoustic oscillations  
  Abstract Gravity constrains the range of validity of quantum field theory. As has been pointed out by Cohen, Kaplan, and Nelson (CKN), such effects lead to interdependent ultraviolet (UV) and infrared (IR) cutoffs that may stabilize the dark energy of the universe against quantum corrections, if the IR cutoff is set by the Hubble horizon. As a consequence of the cosmic expansion, this argument implies a time-dependent dark energy density. In this paper we confront this idea with recent data from DESI BAO, Hubble and supernova measurements. We find that the CKN model provides a better fit to the data than the Lambda CDM model and can compete with other models of time-dependent dark energy that have been studied so far.  
  Address [Adolf, Patrick; Krieg, Sara; Paes, Heinrich; Tabet, Mustafa] Tech Univ Dortmund, Fak Phys, D-44221 Dortmund, Germany, Email: patrick.adolf@tu-dortmund.de;  
  Corporate Author Thesis  
  Publisher IOP Publishing Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1475-7516 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:001319332300014 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 6303  
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