A new and gauge-invariant Littlest Higgs model with T-parity
José Ignacio Illana,
José María Pérez-Poyatos
Abstract:We inspect the Littlest Higgs model with T-parity, based on a global symmetry SU(5) spontaneously broken to SO(5), in order to elucidate the pathologies it presents due to the non trivial interplay between the gauge invariance associated to the heavy modes and the discrete T-parity symmetry. In particular, the usual Yukawa Lagrangian responsible for providing masses to the heavy 'mirror' fermions is not gauge invariant. This is because it contains an SO(5) quintuplet of right-handed fermions that transforms no… Show more
“…As a result, direct and indirect constraints on the LHT are significantly relaxed [21,22]. Thus, the LHT remains phenomenologically viable and well-motivated [23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,44,45,46,47].…”
Section: Introductionmentioning
confidence: 99%
“…We postpone to future work the complete analysis within the LHT keeping the O(v 2 /f 2 ) contributions to the form factors. This shall be necessary, since the heavy Majorana neutrinos have to have O(TeV) masses, as the T-odd particles, within a gauge invariant theory[47]. We will also need to study first semileptonic LFV tau decays within the LHT (following Refs [67,68,69]…”
We study lepton flavor violation (LFV) within the Littlest Higgs Model with T parity (LHT) realizing an inverse seesaw (ISS) mechanism of type I. With respect to the traditional LHT, there appear new O(TeV) Majorana neutrinos, driving LFV. For τ → ¯ (including wrong-sign, = e, µ) decays and µ → e conversion in Ti, we get typical rates only one order of magnitude below present bounds ( → γ can reach the current upper limit) and for Z → τ , µ → eeē and conversion in Au, results are within two orders of magnitude from present limits. Correlations among modes are drastically different to the traditional LHT and other models, which would ease the confrontation of this scenario to eventual measurements of LFV processes involving charged leptons.
“…As a result, direct and indirect constraints on the LHT are significantly relaxed [21,22]. Thus, the LHT remains phenomenologically viable and well-motivated [23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,44,45,46,47].…”
Section: Introductionmentioning
confidence: 99%
“…We postpone to future work the complete analysis within the LHT keeping the O(v 2 /f 2 ) contributions to the form factors. This shall be necessary, since the heavy Majorana neutrinos have to have O(TeV) masses, as the T-odd particles, within a gauge invariant theory[47]. We will also need to study first semileptonic LFV tau decays within the LHT (following Refs [67,68,69]…”
We study lepton flavor violation (LFV) within the Littlest Higgs Model with T parity (LHT) realizing an inverse seesaw (ISS) mechanism of type I. With respect to the traditional LHT, there appear new O(TeV) Majorana neutrinos, driving LFV. For τ → ¯ (including wrong-sign, = e, µ) decays and µ → e conversion in Ti, we get typical rates only one order of magnitude below present bounds ( → γ can reach the current upper limit) and for Z → τ , µ → eeē and conversion in Au, results are within two orders of magnitude from present limits. Correlations among modes are drastically different to the traditional LHT and other models, which would ease the confrontation of this scenario to eventual measurements of LFV processes involving charged leptons.
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