Simple SUSY GUT models based on the gauge group SO(10) require t-b-t Yukawa
coupling unification, in addition to gauge coupling and matter unification. The Yukawa
coupling unification places a severe constraint on the expected spectrum of
superpartners, with scalar masses ~ 10 TeV while gaugino masses are quite light. For
Yukawa-unified models with μ > 0, the spectrum is characterized by three mass scales:
i). first and second generation scalars in the multi-TeV range, ii). third generation
scalars, μ and mA in the few-TeV range and iii). gluinos in the ~ 350−500 GeV range with
chargino masses around 100−160 GeV. In such a scenario, gluino pair production should
occur at large rates at the CERN LHC, followed by gluino three-body decays into
neutralinos or charginos. Discovery of Yukawa-unified SUSY at the LHC should hence be
possible with only 1 fb−1 of integrated luminosity, by tagging multi-jet events with 2–3
isolated leptons, without relying on missing ET . A characteristic dilepton mass edge
should easily be apparent above Standard Model background. Combining dileptons with
b-jets, along with the gluino pair production cross section information, should allow
for gluino and neutralino mass reconstruction. A secondary corroborative signal should
be visible at higher integrated luminosity in the X1±1X20 → 3l channel, and should
exhibit the same dilepton mass edge as in the gluino cascade decay signal. A problem
generic to all supergravity models comes from overproduction of gravitinos in the early
universe: if gravitinos are unstable, then their late decays may destroy the predictions
of Big Bang nucleosynthesis. We also present a Yukawa-unified SO(10) SUSY GUT scenario
which avoids the gravitino problem, gives rise to the correct matter-antimatter
asymmetry via non-thermal leptogenesis, and is consistent with the WMAP-measured
abundance of cold dark matter due to the presence of an axino LSP. To maintain a
consistent cosmology for Yukawa-unified SUSY models, we require a re-heat temperature TR
~ 106−107 GeV, an axino mass around 0.1−10 MeV, and a Peccei-Quinn breaking scale fa ~
1012 GeV. / A Dissertation submitted to the Department of Physics in partial fulfillment of the
requirements for the degree of Doctor of Philosophy. / Degree Awarded: Fall Semester, 2008. / Date of Defense: September 12, 2008. / Supersymmetry (SUSY), Grand Unification (GUT), Dark Matter, Phenomenology, Collider Physics, Large Hadron Collider (LHC), Cern, Mulitlepton, Axino / Includes bibliographical references. / Howard Baer, Professor Directing Dissertation; Mark Sussman, Outside Committee Member; Laura Reina, Committee Member; Horst Wahl, Committee Member; Efstratios Manousakis, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_168550 |
| Contributors | Summy, Heaya Ann (authoraut), Baer, Howard (professor directing dissertation), Sussman, Mark (outside committee member), Reina, Laura (committee member), Wahl, Horst (committee member), Manousakis, Efstratios (committee member), Department of Physics (degree granting department), Florida State University (degree granting institution) |
| Publisher | Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text |
| Format | 1 online resource, computer, application/pdf |
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