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Author Hirsch, M.; Porod, W.; Weiss, C.; Staub, F. url  doi
openurl 
  Title Supersymmetric type-III seesaw mechanism: Lepton flavor violation and LHC phenomenology Type Journal Article
  Year 2013 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 87 Issue 1 Pages 013010 - 12pp  
  Keywords (up)  
  Abstract We study a supersymmetric version of the type-III seesaw mechanism considering two variants of the model: a minimal version for explaining neutrino data with only two copies of 24 superfields and a model with three generations of 24-plets. The latter predicts, in general, rates for μ-> e gamma inconsistent with experimental data. However, this bound can be evaded if certain special conditions within the neutrino sector are fulfilled. In the case of two 24-plets, lepton flavor violation constraints can be satisfied much more easily. After specifying the corresponding regions in the minimal supergravity parameter space, we show that under favorable conditions one can test the corresponding flavor structures in the leptonic sector at the LHC. For this we perform Monte Carlo studies for the signals, also taking into account the supersymmetry background. We find that it is only of minor importance for the scenarios studied here.  
  Address [Hirsch, M.] Univ Valencia, CSIC, Inst Fis Corpuscular, AHEP Grp, 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:000313945700001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1310  
Permanent link to this record
 
 
Author Deppisch, F.F.; Hirsch, M.; Pas, H. url  doi
openurl 
  Title Neutrinoless double-beta decay and physics beyond the standard model Type Journal Article
  Year 2012 Publication Journal of Physics G Abbreviated Journal J. Phys. G  
  Volume 39 Issue 12 Pages 124007 - 23pp  
  Keywords (up)  
  Abstract Neutrinoless double-beta decay is the most powerful tool to probe not only for Majorana neutrino masses but for lepton number violating physics in general. We discuss relations between lepton number violation, double-beta decay and neutrino mass, review a general Lorentz-invariant parametrization of the double-beta decay rate, highlight a number of different new physics models showing how different mechanisms can trigger double-beta decay and, finally, discuss possibilities of discriminating and testing these models and mechanisms in complementary experiments.  
  Address [Deppisch, Frank F.] UCL, Dept Phys & Astron, London, England, Email: f.deppisch@ucl.ac.uk;  
  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:000315520400008 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1347  
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 Helo, J.C.; Kovalenko, S.G.; Hirsch, M.; Pas, H. url  doi
openurl 
  Title Neutrinoless double beta decay and lepton number violation at the LHC Type Journal Article
  Year 2013 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 88 Issue 1 Pages 011901 - 5pp  
  Keywords (up)  
  Abstract We compare the discovery potential of the LHC for lepton number violating (LNV) signals with the sensitivity of current and future double beta decay experiments, assuming 0 nu beta beta decay is dominated by heavy particle exchange. We consider charged scalar, leptoquark and diquark mechanisms of 0 nu beta beta decay, covering the 0 nu beta beta decay operators with both, the smallest and largest, possible rates. We demonstrate, if 0 nu beta beta decay were found with a half-life below 10(26)-10(27) years a positive signal should show up at the LHC, except for some particular cases of the leptoquark mechanism, and vice versa, if the LHC does not find any hints for LNV, a “short-range” explanation for a finite 0 nu beta beta decay half-life will be ruled out in most cases. We argue, if a positive LNV signal were found at the LHC, it is possible to identify the dominant contribution to 0 nu beta beta. Two different kinds of observables which could provide such “model discriminating” power are discussed: different invariant mass peaks and the charge asymmetry.  
  Address [Helo, J. C.; Kovalenko, S. G.] Univ Tecn Federico Santa Maria, Ctr Cient Tecnol Valparaiso, Valparaiso, Chile, Email: juan.heloherrera@gmail.com;  
  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:000322225900001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1523  
Permanent link to this record
 
 
Author Helo, J.C.; Kovalenko, S.G.; Hirsch, M.; Pas, H. url  doi
openurl 
  Title Short-range mechanisms of neutrinoless double beta decay at the LHC Type Journal Article
  Year 2013 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 88 Issue 7 Pages 073011 - 19pp  
  Keywords (up)  
  Abstract Lepton number violation (LNV) mediated by short- range operators can manifest itself in both neutrinoless double beta decay (0 nu beta beta) and in processes with same- sign dilepton final states at the LHC. We derive limits from existing LHC data at root s = 8 TeV and compare the discovery potential of the forthcoming root s = 14 TeV phase of the LHC with the sensitivity of current and future 0 nu beta beta decay experiments, assuming the short-range part of the 0 nu beta beta decay amplitude dominates. We focus on the first of two possible topologies triggered by one fermion and two bosons in the intermediate state. In all cases, except for the pure leptoquark mechanism, the LHC will be more sensitive than 0 nu beta beta decay in the future. In addition, we propose to search for a charge asymmetry in the final state leptons and to use different invariant mass peaks as a possible tool to discriminate the various possible mechanisms for LNV signals at the LHC.  
  Address [Helo, J. C.; Kovalenko, S. G.] Univ Tecn Federico Santa Maria, Ctr Cient Tecnol Valparaiso, Valparaiso, Chile, Email: juan.heloherrera@gmail.com;  
  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:000326111000002 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1627  
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  
Permanent link to this record
 
 
Author Helo, J.C.; Kovalenko, S.G.; Hirsch, M. url  doi
openurl 
  Title Heavy neutrino searches at the LHC with displaced vertices Type Journal Article
  Year 2014 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 89 Issue 7 Pages 073005 - 7pp  
  Keywords (up)  
  Abstract Sterile neutrinos with masses in the range of 1-100 GeV have been searched for in a variety of experiments. Here, we discuss the prospects of searching for sterile neutrinos at the LHC using displaced vertices. Two different cases are discussed: (i) the standard model extended with sterile neutrinos, and (ii) right-handed neutrinos in a left-right symmetric extension of the standard model. A dedicated displaced vertex search will allow us to probe parts of the parameter space not accessible to other searches, but both cases will require a large luminosity.  
  Address [Helo, J. C.; Kovalenko, S. G.] Univ Tecn Federico Santa Maria, Ctr Cient Tecnol Valparaiso, Valparaiso, Chile, Email: juancarlos.helo@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 1550-7998 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000334314500002 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 1756  
Permanent link to this record
 
 
Author Deppisch, F.F.; Harz, J.; Hirsch, M. url  doi
openurl 
  Title 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 (up)  
  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 Fonseca, R.M.; Hirsch, M. url  doi
openurl 
  Title SU(5)-inspired double beta decay Type Journal Article
  Year 2015 Publication Physical Review D Abbreviated Journal Phys. Rev. D  
  Volume 92 Issue 1 Pages 015014 - 14pp  
  Keywords (up)  
  Abstract The short-range part of the neutrinoless double beta amplitude is generated via the exchange of exotic particles, such as charged scalars, leptoquarks and/or diquarks. In order to give a sizable contribution to the total decay rate, the masses of these exotics should be of the order of (at most) a few TeV. Here, we argue that these exotics could be the “light” (i.e., weak-scale) remnants of some B – L violating variants of SU(5). We show that unification of the standard model gauge couplings, consistent with proton decay limits, can be achieved in such a setup without the need to introduce supersymmetry. Since these nonminimal SU(5)-inspired models violate B – L, they generate Majorana neutrino masses and therefore make it possible to explain neutrino oscillation data. The light colored particles of these models can potentially be observed at the LHC, and it might be possible to probe the origin of the neutrino masses with Delta L = 2 violating signals. As particular realizations of this idea, we present two models, one for each of the two possible tree-level topologies of neutrinoless double beta decay.  
  Address [Fonseca, Renato M.; Hirsch, Martin] Univ Valencia, AHEP Grp, CSIC, Inst Fis Corpuscular, E-46071 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  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1550-7998 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000357860200006 Approved no  
  Is ISI yes International Collaboration no  
  Call Number IFIC @ pastor @ Serial 2300  
Permanent link to this record
 
 
Author Deppisch, F.F.; Harz, J.; Huang, W.C.; Hirsch, M.; Pas, H. url  doi
openurl 
  Title 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 (up)  
  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
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