Minimal supersymmetric b-l and left-right models

dc.contributor.advisorOkada, Nobuchika
dc.contributor.authorPapapietro, Nathan
dc.contributor.otherUniversity of Alabama Tuscaloosa
dc.descriptionElectronic Thesis or Dissertationen_US
dc.description.abstractWe propose a simple gauged U(1)B−L extension of the minimal supersymmetric Standard Model (MSSM), where R-parity is conserved as usual in the MSSM. The global B−L (baryon minus lepton number) symmetry in the MSSM is gauged and three MSSM gauge-singlet chiral multiplets with a unit B −L charge are introduced, ensuring the model free from gauge and gravitational anomalies. We assign an odd R-parity for two of the new chiral multiplets The scalar component of the R-parity even superfield plays the role of a Higgs field to beak the U (1)BL symmetry through its negative mass squared which is radiatively generated by the renormalization group running of soft supersymmetry (SUSY) breaking parameters. Because of our novel R-parity assignment, three light neutrinos are Dirac particles with one massless state. Since R-parity is conserved, the lightest superpartner (LSP) neutralino is a prime candidate of the cosmological dark matter. In particular, the B − L gauge boson (Z ), once discovered at the Large Hadron Collider, will be a novel probe of the Dirac nature of the light neutrinos since its invisible decay processes include the final states with one massless (left-handed) neutrino and two Dirac neutrinos, in sharp contrast with the conventional B − L extension of the SM or MSSM, where the right-handed neutrinos are heavy Majorana particles and decay to the SM leptons. We generalize a variation to the SUSY Left-Right symmetric model based on the gauge group SU (3)c × SU (2)L × SU (2)R × U (1)BL . The charge conjugate SU (2)L singlets are put into SU (2)R doublets, mirroring the former. We only introduce a second Higgs bidoublet to produce realistic fermion mass matrices. We calculate renormalization group evolutions of soft SUSY parameters at the one-loop level down to low energy. We find that an SU (2)R slepton doublet acquires a negative mass squared at low energies, so that the breaking of SU (2)R × U (1)BL → U (1)Y is realized by a non-zero vacuum expectation value of a right-handed sneutrino. Small neutrino masses are produced through neutrino mixings with gauginos. Mass limits on the SU (2)R × U (1)BL sector are obtained by direct search results at the LHC as well as lepton-gaugino mixing bounds from the LEP precision data.en_US
dc.format.extent89 p.
dc.publisherUniversity of Alabama Libraries
dc.relation.hasversionborn digital
dc.relation.ispartofThe University of Alabama Electronic Theses and Dissertations
dc.relation.ispartofThe University of Alabama Libraries Digital Collections
dc.rightsAll rights reserved by the author unless otherwise indicated.en_US
dc.subjectParticle physics
dc.titleMinimal supersymmetric b-l and left-right modelsen_US
dc.typetext of Alabama. Department of Physics and Astronomy University of Alabama
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