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Author Anamiati, G.; De Romeri, V.; Hirsch, M.; Ternes, C.A.; Tortola, M. url  doi
openurl 
  Title Quasi-Dirac neutrino oscillations at DUNE and JUNO Type Journal Article
  Year 2019 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 100 Issue 3 Pages 035032 - 12pp  
  Keywords  
  Abstract Quasi-Dirac neutrinos are obtained when the Lagrangian density of a neutrino mass model contains both Dirac and Majorana mass terms, and the Majorana terms are sufficiently small. This type of neutrino introduces new mixing angles and mass splittings into the Hamiltonian, which will modify the standard neutrino oscillation probabilities. In this paper, we focus on the case where the new mass splittings are too small to be measured, but new angles and phases are present. We perform a sensitivity study for this scenario for the upcoming experiments DUNE and JUNO, finding that they will improve current bounds on the relevant parameters. Finally, we also explore the discovery potential of both experiments, assuming that neutrinos are indeed quasi-Dirac particles.  
  Address [Anamiati, G.; De Romeri, V.; Hirsch, M.; Ternes, C. A.; Tortola, M.] Univ Valencia, CSIC, Inst Fis Corpuscular, Paterna 46980, Spain, Email: anamiati@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 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000482944200007 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 4124  
Permanent link to this record
 

 
Author Arbelaez, C.; Helo, J.C.; Hirsch, M. url  doi
openurl 
  Title Long-lived heavy particles in neutrino mass models Type Journal Article
  Year 2019 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 100 Issue 5 Pages 055001 - 15pp  
  Keywords  
  Abstract All extensions of the standard model that generate Majorana neutrino masses at the electroweak scale introduce some heavy mediators, either fermions and/or scalars, weakly coupled to leptons. Here, by “heavy,” we mean implicitly the mass range between a few 100 GeV up to, say, roughly 2 TeV, such that these particles can be searched for at the LHC. We study decay widths of these mediators for several different tree-level neutrino mass models. The models we consider range from the simplest d = 5 seesaw up to d = 11 neutrino mass models. For each of the models, we identify the most interesting parts of the parameter space, where the heavy mediator fields are particularly long lived and can decay with experimentally measurable decay lengths. One has to distinguish two different scenarios, depending on whether fermions or scalars are the lighter of the heavy particles. For fermions, we find that the decay lengths correlate with the inverse of the overall neutrino mass scale. Thus, since no lower limit on the lightest neutrino mass exists, nearly arbitrarily long decay lengths can be obtained for the case in which fermions are the lighter of the heavy particles. For charged scalars, on the other hand, there exists a maximum value for the decay length in these models. This maximum value depends on the model and on the electric charge of the scalar under consideration but can at most be of the order of a few millimeters. Interestingly, independent of the model, this maximum occurs always in a region of parameter space, where leptonic and gauge boson final states have similar branching ratios, i.e., where the observation of lepton number-violating final states from scalar decays is possible.  
  Address [Arbelaez, Carolina] Univ Tecn Federico Santa Maria, Casilla 110-V, 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:000483583000006 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4127  
Permanent link to this record
 

 
Author Carquin, E.; Neill, N.A.; Helo, J.C.; Hirsch, M. url  doi
openurl 
  Title 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. url  doi
openurl 
  Title Proton decay at one loop Type Journal Article
  Year 2019 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 99 Issue 9 Pages 095021 - 14pp  
  Keywords  
  Abstract Proton decay is usually discussed in the context of grand unified theories. However, as is well known, in the standard model effective theory proton decay appears in the form of higher-dimensional non-renormalizable operators. Here, we study systematically the one-loop decomposition of the d = 6 B + L violating operators. We exhaustively list the possible one-loop ultraviolet completions of these operators and discuss that, in general, two distinct classes of models appear. Models in the first class need an additional symmetry in order to avoid tree-level proton decay. These models necessarily contain a neutral particle, which could act as a dark matter candidate. For models in the second class the loop contribution dominates automatically over the tree-level proton decay, without the need for additional symmetries. We also discuss possible phenomenology of two example models, one from each class, and their possible connections to neutrino masses, LHC searches and dark matter.  
  Address [Helo, Juan Carlos] Univ La Serena, Dept Fis, Fac Ciencias, Ave Cisternas 1200, La Serena 1200, Chile, Email: jchelo@userena.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:000469019900005 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4035  
Permanent link to this record
 

 
Author Alimena, J. et al; Hirsch, M.; Mamuzic, J.; Mitsou, V.A.; Santra, A. url  doi
openurl 
  Title Searching for long-lived particles beyond the Standard Model at the Large Hadron Collider Type Journal Article
  Year 2020 Publication Journal of Physics G Abbreviated Journal J. Phys. G  
  Volume 47 Issue 9 Pages 090501 - 226pp  
  Keywords beyond the Standard Model; long-lived particles; Large Hadron Collider; high-luminosity LHC; collider phenomenology; high-energy collider experiments  
  Abstract Particles beyond the Standard Model (SM) can generically have lifetimes that are long compared to SM particles at the weak scale. When produced at experiments such as the Large Hadron Collider (LHC) at CERN, these long-lived particles (LLPs) can decay far from the interaction vertex of the primary proton-proton collision. Such LLP signatures are distinct from those of promptly decaying particles that are targeted by the majority of searches for new physics at the LHC, often requiring customized techniques to identify, for example, significantly displaced decay vertices, tracks with atypical properties, and short track segments. Given their non-standard nature, a comprehensive overview of LLP signatures at the LHC is beneficial to ensure that possible avenues of the discovery of new physics are not overlooked. Here we report on the joint work of a community of theorists and experimentalists with the ATLAS, CMS, and LHCb experiments-as well as those working on dedicated experiments such as MoEDAL, milliQan, MATHUSLA, CODEX-b, and FASER-to survey the current state of LLP searches at the LHC, and to chart a path for the development of LLP searches into the future, both in the upcoming Run 3 and at the high-luminosity LHC. The work is organized around the current and future potential capabilities of LHC experiments to generally discover new LLPs, and takes a signature-based approach to surveying classes of models that give rise to LLPs rather than emphasizing any particular theory motivation. We develop a set of simplified models; assess the coverage of current searches; document known, often unexpected backgrounds; explore the capabilities of proposed detector upgrades; provide recommendations for the presentation of search results; and look towards the newest frontiers, namely high-multiplicity 'dark showers', highlighting opportunities for expanding the LHC reach for these signals.  
  Address [Alimena, Juliette; Hill, Christopher S.] Ohio State Univ, Dept Phys, 191 W Woodruff Ave, Columbus, OH 43210 USA, Email: juliette.alimena@cern.ch;  
  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 0954-3899 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000570614200001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4535  
Permanent link to this record
 

 
Author Cottin, G.; Helo, J.C.; Hirsch, M.; Silva, D. url  doi
openurl 
  Title Revisiting the LHC reach in the displaced region of the minimal left-right symmetric model Type Journal Article
  Year 2019 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 99 Issue 11 Pages 115013 - 4pp  
  Keywords  
  Abstract We revisit discovery prospects for a long-lived sterile neutrino N at the LHC in the context of left-right symmetric theories. We focus on a displaced vertex search strategy sensitive to O(GeV) neutrino masses produced via a right-handed W-R boson. Both on-shell and off-shell Drell-Yan production of W-R are considered. We estimate the reach as a function of m(N) and m(WR). With root s = 13 TeV and 300/fb of integrated luminosity, the LHC can probe neutrino masses as high as approximately 30 GeV and m(wR) around 6 TeV. The reach goes up to 11.5 TeV with 3000/tb and m(N) similar to 45 GeV. This represents an improvement of a factor of 2 in sensitivity with respect to earlier work.  
  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:000470867500008 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4055  
Permanent link to this record
 

 
Author Cordero-Carrion, I.; Hirsch, M.; Vicente, A. url  doi
openurl 
  Title Master Majorana neutrino mass parametrization Type Journal Article
  Year 2019 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 99 Issue 7 Pages 075019 - 6pp  
  Keywords  
  Abstract After introducing a master formula for the Majorana neutrino mass matrix, we present a master parametrization for the Yukawa matrices automatically in agreement with neutrino oscillation data. This parametrization can be used for any model that induces Majorana neutrino masses. The application of the master parametrization is also illustrated in an example model, with special focus on its lepton flavor violating phenomenology.  
  Address [Cordero-Carrion, I.] Univ Valencia, Dept Matemat, E-46100 Valencia, Spain, Email: isabel.cordero@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 2470-0010 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000464743100007 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 3981  
Permanent link to this record
 

 
Author Dercks, D.; Dreiner, H.K.; Hirsch, M.; Wang, Z.S. url  doi
openurl 
  Title Long-lived fermions at AL3X Type Journal Article
  Year 2019 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 99 Issue 5 Pages 055020 - 10pp  
  Keywords  
  Abstract Recently Gligorov et al. [V. V. Gligorov et al., Phys. Rev. D 99, 015023 (2019)] proposed to build a cylindrical detector named AL3X close to the ALICE experiment at interaction point (IP) 2 of the LHC, aiming for discovery of long-lived particles (LLPs) during Run 5 of the HL-LHC. We investigate the potential sensitivity reach of this detector in the parameter space of different new-physics models with long-lived fermions namely heavy neutral leptons (HNLs) and light supersymmetric neutralinos, which have both not previously been studied in this context. Our results show that the AL3X reach can be complementary or superior to that of other proposed detectors such as CODEX-b, FASER, MATHUSLA and SHiP.  
  Address [Dercks, Daniel] DESY, Notkestr 85, D-22607 Hamburg, Germany, Email: daniel.dercks@desy.de;  
  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:000461906400007 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 3949  
Permanent link to this record
 

 
Author Cepedello, R.; Deppisch, F.F.; Gonzalez, L.; Hati, C.; Hirsch, M. url  doi
openurl 
  Title Neutrinoless Double-Beta Decay with Nonstandard Majoron Emission Type Journal Article
  Year 2019 Publication Physical Review Letters Abbreviated Journal Phys. Rev. Lett.  
  Volume 122 Issue 18 Pages 181801 - 6pp  
  Keywords  
  Abstract We present a novel mode of neutrinoless double-beta decay with emission of a light Majoron-like scalar particle phi. We assume it couples via an effective seven-dimensional operator with a (V + A) lepton current and (V +/- A) quark currents leading to a long-range contribution that is unsuppressed by the light neutrino mass. We calculate the total double-beta decay rate and determine the fully differential shape for this mode. We find that future double-beta decay searches are sensitive to scales of the order Lambda(NP) approximate to 1 TeV for the effective operator and a light scalar m(phi) < 0.2 MeV, based on ordinary double-beta decay Majoron searches. The angular and energy distributions can deviate considerably from that of two-neutrino double-beta decay, which is the main background. We point out possible ultraviolet completions where such an effective operator can emerge.  
  Address [Cepedello, Ricardo; Hirsch, Martin] 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 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:000467042800001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4002  
Permanent link to this record
 

 
Author Curtin, D. et al; Hirsch, M. url  doi
openurl 
  Title Long-lived particles at the energy frontier: the MATHUSLA physics case Type Journal Article
  Year 2019 Publication Reports on Progress in Physics Abbreviated Journal Rep. Prog. Phys.  
  Volume 82 Issue 11 Pages 116201 - 133pp  
  Keywords Large Hadron Collider; long-lived particles; hierarchy problem; dark matter; baryogenesis; neutrinos; simplified models  
  Abstract We examine the theoretical motivations for long-lived particle (LLP) signals at the LHC in a comprehensive survey of standard model (SM) extensions. LLPs are a common prediction of a wide range of theories that address unsolved fundamental mysteries such as naturalness, dark matter, baryogenesis and neutrino masses, and represent a natural and generic possibility for physics beyond the SM (BSM). In most cases the LLP lifetime can be treated as a free parameter from the μm scale up to the Big Bang Nucleosynthesis limit of similar to 10(7) m. Neutral LLPs with lifetimes above similar to 100 m are particularly difficult to probe, as the sensitivity of the LHC main detectors is limited by challenging backgrounds, triggers, and small acceptances. MATHUSLA is a proposal for a minimally instrumented, large-volume surface detector near ATLAS or CMS. It would search for neutral LLPs produced in HL-LHC collisions by reconstructing displaced vertices (DVs) in a low-background environment, extending the sensitivity of the main detectors by orders of magnitude in the long-lifetime regime. We study the LLP physics opportunities afforded by a MATHUSLA-like detector at the HL-LHC, assuming backgrounds can be rejected as expected. We develop a model-independent approach to describe the sensitivity of MATHUSLA to BSM LLP signals, and compare it to DV and missing energy searches at ATLAS or CMS. We then explore the BSM motivations for LLPs in considerable detail, presenting a large number of new sensitivity studies. While our discussion is especially oriented towards the long-lifetime regime at MATHUSLA, this survey underlines the importance of a varied LLP search program at the LHC in general. By synthesizing these results into a general discussion of the top-down and bottom-up motivations for LLP searches, it is our aim to demonstrate the exceptional strength and breadth of the physics case for the construction of the MATHUSLA detector.  
  Address [Curtin, David] Univ Toronto, Dept Phys, Toronto, ON M5S 1A7, Canada, Email: dcurtin@physics.utoronto.ca  
  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 0034-4885 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000499698000001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4215  
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