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SUSY SO(10) and its implications for colliders and cosmology. Tomáš Blažek Comenius Univ, Bratislava. CERN, 9 Aug 2007. Contents. Why SO(10) Main Experimental Constraints and Their Effects Examples of Best Fits from the Global Top-Down Analysis Implications for SUSY searches.
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SUSY SO(10) and its implications for colliders and cosmology Tomáš Blažek Comenius Univ, Bratislava CERN, 9 Aug 2007
Contents • Why SO(10) • Main Experimental Constraints and Their Effects • Examples of Best Fits from the Global Top-Down Analysis • Implications for SUSY searches
Well-Known SO(10) Virtues • SM fermionic multiplets of one family × 3 colours + fit nicely into the 16 of SO(10): • the 16 is a chiral rep -> there’s no singlet in 16×16 -> it is massless at the SO(10) level • anomaly canceled automatically, since SO(10) is anomaly free, unlike SU(3)c×SU(2)L×U(1)Y or SU(5) • the extra 16th state has quantum numbers of νR, and is not protected against geting massive below MGUT setting stage for the L number violation and see-saw mechanism after EWSB • Similarly the two Higgs doublets fit into a massless 10 • Gauge couplings unify
Well-Known SO(10) Virtues cont’d • The 16310163 operator gives order one yukawa coupling: • get a heavy top quark • EW symmetry broken radiatively (for universal scalar masses) • prediction • yt ≈ yb ≈ ytau ≈ yνtau • includes successful idea of b-tau unification • The see-saw mechanism then predicts about the right hierarchy between the charged fermions and much lighter neutrinos • ... and there is more that is less well-known and is coming in this talk
SO(10) Troubles • Have you seen a proton decaying lately? (dim 5 operator due to the coloured triplet higgs vs. the sign of the MGUT correction to αs ) • The 16310163 operator gives order one yukawa coupling: • Prediction • yt ≈ yb • implies large amount of fine tuning at EWSB scale: must get vd≈3GeV, as mt(MZ)/mb(MZ)≈50, • i.e., need large tanβ • Moreover, scalar higgs masses run very steep – Fig. • Since mc/mt« ms/mb, mmu/mtau and also • mu/mc« md/ms, • different higher-dimensional operators generate fermion masses of the two lighter generations • UV completion ?
SO(10) studies • Approach 1: study a particular model, which can be more or less complete, generating higher dimensional operators, and filling in the 3×3 yukawa matrices at MGUT by reading out the individual entries from the Frogatt-Nielsen diagrams OR • Approach 2: be less specific and study „SO(10)-like models“ in an MSSM analysis below MGUT which just takes into account the large yukawa couplings of the third generation
SO(10) studies Approach 1: Implemented in • and a number of follow-up papers. • Strategy: Do pure top-down global analysis evaluating χ2from the comparison with the available low energy data. See Table. • Important details: • Include GUT threshold correction to αs • Gravity mediated SUSY breaking with non-universal scalar higgs masses • Face fine tuning with an embedded minimisation procedure, separately minimising χ2using the non-universal higgs masses for each set of the GUT parameters
Table of Low Energy Observables MSSM analysis only
BR(b sγ) Constraint Effective Hamiltonian: ~ where η= αs(MZ) / αs(μ) Contributions to C7(MZ): chargino diagram enhanced by tanβ picks up the sign of the μ parameter SUSY CKM contrib non-negligible C7 or
mb(mb) Constraint Large SUSY Threshold Contributions to mb(MZ): • both diagrams enhanced by tanβ and proportional to μ • must be of opposite signs: need negative At • still potentially too large: pushes μ to low values ... get low mass higgsino-like charginos and neutralinos • for the same reason the global analysis best fits prefer heavy gluino. That means rather large M1/2 which through the RGEs feeds into large scalar masses.
Constraint from the muon anomalous magn moment SUSY Contributions to aμ: • both diagrams enhanced by tanβ and proportional to μ, chargino contribution typically greater • no freedom to choose the sign: could have gone the opposite way than the BNL measurement, but it has not • the low value of μ and heavy scalar masses tend to prefer lesser contribution than what is measured in the e+e- exp. • If the result stays, it could be a hint for a non-universal SUSY breaking mechanism.
Constraint from non-observation of Bs to μ+μ- SUSY contributions to this decay amplitude are enhanced by (tanβ)3. In this amplitude the process is mediated by the pseudoscalar higgs exchange. • need pseudoscalar higgs mass typically greater than 300 GeV
Implications from the SO(10)-like models best fits • the lightest CP even higgs very close to the current limit mh ≈ 115-120 GeV • the rest of the higgs spectrum above ≈ 250-300 GeV • light higgsino-like charginos and neutralinos close to 100 GeV, the LSP is most of the times a higgsino-like neutralino • possibly a light stop and stau (and maybe sbottom) due to the large left-right splittings • the rest of the MSSM sparticle spectrum at/above the TeV scale • CDM is formed by a mixture of bino/higgsino-like neutralino LSP and should be observed in the near future, or the LSP is higgsino-like LSP that annihilates too rapidly to form the dominant CDM component