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Title: Unconventional neutrino mass generation, neutrinoless double beta decays, and collider phenomenology

Abstract

We study a model in which lepton number violation is solely triggered by a dimension 4 hard breaking term in the scalar potential. A minimal model, which contains a SU(2) triplet with hypercharge Y=2 and a pair of singlet doubly charged scalar fields in addition to the standard model (SM) Higgs doublet, is constructed. The model is technically natural in the sense that lepton number is preserved in the limit that the hard term vanishes. SM phenomenology restricts the vacuum expectation value of the triplet scalar field v{sub T}<5.78 GeV. Neutrino masses controlled by v{sub T} are generated at the two loop level and are naturally in the sub-eV range. In general they exhibit normal hierarchy structure. Here the neutrino mass term does not dominate neutrinoless double beta decays of nuclei. Instead the short-distance physics with doubly charged Higgs exchange gives the leading contribution. We expect weak scale singly and doubly charged Higgs bosons to make their appearances at the LHC and the ILC.

Authors:
;  [1];  [2];  [3]
  1. Department of Physics, National Tsing Hua University, Hsinchu, Taiwan 300 (China)
  2. (Canada)
  3. Theory group, TRIUMF, 4004 Wesbrook Mall, Vancouver, B.C. V6T 2A3 (Canada)
Publication Date:
OSTI Identifier:
21020044
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 75; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevD.75.053004; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; CERN LHC; DOUBLE BETA DECAY; EXPECTATION VALUE; FOUR-DIMENSIONAL CALCULATIONS; GEV RANGE; HIGGS BOSONS; HIGGS MODEL; HYPERCHARGE; LEPTON NUMBER; NEUTRINOS; POTENTIALS; REST MASS; SCALAR FIELDS; STANDARD MODEL; SU-2 GROUPS

Citation Formats

Chen, C.-S., Geng, C. Q., Theory group, TRIUMF, 4004 Wesbrook Mall, Vancouver, B.C. V6T 2A3, and Ng, J. N. Unconventional neutrino mass generation, neutrinoless double beta decays, and collider phenomenology. United States: N. p., 2007. Web. doi:10.1103/PHYSREVD.75.053004.
Chen, C.-S., Geng, C. Q., Theory group, TRIUMF, 4004 Wesbrook Mall, Vancouver, B.C. V6T 2A3, & Ng, J. N. Unconventional neutrino mass generation, neutrinoless double beta decays, and collider phenomenology. United States. doi:10.1103/PHYSREVD.75.053004.
Chen, C.-S., Geng, C. Q., Theory group, TRIUMF, 4004 Wesbrook Mall, Vancouver, B.C. V6T 2A3, and Ng, J. N. Thu . "Unconventional neutrino mass generation, neutrinoless double beta decays, and collider phenomenology". United States. doi:10.1103/PHYSREVD.75.053004.
@article{osti_21020044,
title = {Unconventional neutrino mass generation, neutrinoless double beta decays, and collider phenomenology},
author = {Chen, C.-S. and Geng, C. Q. and Theory group, TRIUMF, 4004 Wesbrook Mall, Vancouver, B.C. V6T 2A3 and Ng, J. N.},
abstractNote = {We study a model in which lepton number violation is solely triggered by a dimension 4 hard breaking term in the scalar potential. A minimal model, which contains a SU(2) triplet with hypercharge Y=2 and a pair of singlet doubly charged scalar fields in addition to the standard model (SM) Higgs doublet, is constructed. The model is technically natural in the sense that lepton number is preserved in the limit that the hard term vanishes. SM phenomenology restricts the vacuum expectation value of the triplet scalar field v{sub T}<5.78 GeV. Neutrino masses controlled by v{sub T} are generated at the two loop level and are naturally in the sub-eV range. In general they exhibit normal hierarchy structure. Here the neutrino mass term does not dominate neutrinoless double beta decays of nuclei. Instead the short-distance physics with doubly charged Higgs exchange gives the leading contribution. We expect weak scale singly and doubly charged Higgs bosons to make their appearances at the LHC and the ILC.},
doi = {10.1103/PHYSREVD.75.053004},
journal = {Physical Review. D, Particles Fields},
number = 5,
volume = 75,
place = {United States},
year = {Thu Mar 01 00:00:00 EST 2007},
month = {Thu Mar 01 00:00:00 EST 2007}
}
  • We have analyzed the results of the latest terrestrial neutrino oscillation experiments in the framework of a model with mixing of three massive neutrinos and a neutrino mass hierarchy ({ital m}{sub 1}{lt}{ital m}{sub 2}{lt}{ital m}{sub 3}). In this model, oscillations of the terrestrial neutrinos are characterized by three parameters, {Delta}{ital m}{sup 2}{equivalent_to}{ital m}{sup 2}{sub 3}{minus}{ital m}{sup 2}{sub 1} and the squared moduli of the two mixing matrix elements {ital U}{sub {ital e}3} and {ital U}{sub {mu}3}. Using the results of disappearance experiments and solar neutrino experiments, it is shown that only two regions of possible values of {vert_bar}{ital U}{sub {italmore » e}3}{vert_bar}{sup 2} and {vert_bar}{ital U}{sub {mu}3}{vert_bar}{sup 2} are allowed: (I) {vert_bar}{ital U}{sub {ital e}3}{vert_bar}{sup 2} and {vert_bar}{ital U}{sub {mu}3}{vert_bar}{sup 2} are both small and (II) {vert_bar}{ital U}{sub {ital e}3}{vert_bar}{sup 2} is small and {vert_bar}{ital U}{sub {mu}3}{vert_bar}{sup 2} is large. If the mixing parameters are in region I, {nu}{sub {mu}}{sq_bullet}{nu}{sub {ital e}} oscillations are suppressed. In this case the LSND indication in favor of {nu}{sub {mu}}{sq_bullet}{nu}{sub {ital e}} oscillations is not compatible with the negative results of all other experiments. If the mixing parameters are in region II, {nu}{sub {ital e}}{sq_bullet}{nu}{sub {tau}} oscillations are strongly suppressed. If massive neutrinos are Majorana particles, our analysis shows that neutrinoless double-{beta} decay could be observed in the experiments of the next generation only if the mixing parameters are in region I. {copyright} {ital 1996 The American Physical Society.}« less
  • We propose a simple extension of the standard model in which the neutrinoless double-..beta.. decay is a tree-level effect mediated by Higgs bosons and the neutrino mass begins to appear in the two-loop diagrams. The model also contains a massless Majoron, i.e., the Goldstone boson of the global symmetry of the lepton number, which is spontaneously broken at a scale close to that of the electroweak interaction. No unnaturally huge or tiny new scales are evoked. The Majoron coupling to the fermions is also two-loop suppressed.
  • In the framework of the seesaw mechanism the normal hierarchy is favorable for the neutrino mass spectrum. For this spectrum we present a detailed calculation of the half-lives of neutrinoless double {beta}-decay for several nuclei of experimental interest. The half-lives are evaluated by considering the most comprehensive nuclear matrix elements, which were obtained within the renormalized quasiparticle random phase approximation by the Bratislava-Caltech-Tuebingen group. The dependence of the half-lives on sin{sup 2}{theta}{sub 13} and the lightest neutrino mass is studied. We present also the results of the calculations of the half-lives of neutrinoless double {beta}-decay in the case of themore » inverted hierarchy of neutrino masses.« less
  • The ({beta}{sup -}{beta}{sup -}){sub 0{nu}} decay of {sup 94,96}Zr, {sup 98,100}Mo, {sup 104}Ru, {sup 110}Pd, {sup 128,130}Te, and {sup 150}Nd isotopes for the 0{sup +}{yields}0{sup +} transition is studied in the projected Hartree-Fock-Bogoliubov framework. In our earlier work, the reliability of HFB intrinsic wave functions participating in the {beta}{sup -}{beta}{sup -} decay of the above-mentioned nuclei has been established by obtaining an overall agreement between the theoretically calculated spectroscopic properties, namely yrast spectra, reduced B(E2:0{sup +}{yields}2{sup +}) transition probabilities, quadrupole moments Q(2{sup +}), gyromagnetic factors g(2{sup +}) as well as half-lives T{sub 1/2}{sup 2{nu}} for the 0{sup +}{yields}0{sup +} transitionmore » and the available experimental data. In the present work, we study the ({beta}{sup -}{beta}{sup -}){sub 0{nu}} decay for the 0{sup +}{yields}0{sup +} transition in a mechanism involving neutrino mass and extract limits on effective mass of light as well as heavy neutrinos from the observed half-lives T{sub 1/2}{sup 0{nu}}(0{sup +}{yields}0{sup +}) using nuclear transition matrix elements calculated with the same set of wave functions. Further, the effect of deformation on the nuclear transition matrix elements required to study the ({beta}{sup -}{beta}{sup -}){sub 0{nu}} decay in such a mass mechanism is investigated. It is noticed that the deformation effect on nuclear transition matrix elements is of approximately the same magnitude in ({beta}{sup -}{beta}{sup -}){sub 2{nu}} and ({beta}{sup -}{beta}{sup -}){sub 0{nu}} decay.« less
  • If future neutrino oscillation experiments show that the neutrino mass spectrum is with normal ordering, m{sub 1}<m{sub 2}<m{sub 3}, and the searches for neutrinoless double beta [({beta}{beta}){sub 0{nu}}] decay with sensitivity to values of the effective Majorana mass |<m>| > or approx. 10{sup -2} eV give negative results, the next frontier in the quest for ({beta}{beta}){sub 0{nu}}-decay will correspond to |<m>|{approx}10{sup -3} eV. By assuming that massive neutrinos are Majorana particles and their exchange is the dominant mechanism generating ({beta}{beta}){sub 0{nu}}-decay, we analyze the conditions under which |<m>|, in the case of three-neutrino mixing and a neutrino mass spectrum withmore » normal ordering, would satisfy |<m>|{>=}0.001 eV. We consider the specific cases of (i) a normal hierarchical neutrino mass spectrum, (ii) a relatively small value of the CHOOZ angle {theta}{sub 13}, as well as (iii) the general case of a spectrum with normal ordering, a partial hierarchy, and a value of {theta}{sub 13} close to the existing upper limit. We study the ranges of the lightest neutrino mass m{sub 1} and/or of sin{sup 2}{theta}{sub 13} for which |<m>|{>=}0.001 eV and discuss the phenomenological implications of such scenarios. We provide also an estimate of |<m>| when the three-neutrino masses and the neutrino mixing originate from a neutrino mass term of the Majorana type for the (left-handed) flavor neutrinos and {sub j}{sup 3}m{sub j}U{sub ej}{sup 2}=0, but there does not exist a symmetry which forbids the ({beta}{beta}){sub 0{nu}}-decay.« less