355 research outputs found

    Albert algebras over curves of genus zero and one

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    Albert algebras and other Jordan algebras are constructed over curves of genus zero and one, using a generalization of the Tits process and the first Tits construction due to Achhammer.Comment: 37 page

    A New Model for Fermion Masses in Supersymmetric Grand Unified Theories

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    We present a simple model for fermion mass matrices and quark mixing in the context of supersymmetric grand unified theories and show its agreement with experiment. Our model realizes the GUT mass relations md=3mem_d=3m_e, ms=mμ/3m_s= m_\mu/3, mb=mτm_b=m_\tau in a new way and is easily consistent with values of mtm_t suggested by MSSM fits to LEP data.Comment: Latex, 8 p., ITP-SB-93-37 (revised version contains minor changes in some wording and citations; no changes in analytic or numerical results.

    MSSM and Large tanβtan\beta from SUSY Trinification

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    We construct a supersymmetric model based on the semi-simple gauge group SU(3)c×SU(3)L×SU(3)RSU(3)_c \times SU(3)_L \times SU(3)_R with the relation tanβmt/mbtan\beta \simeq m_t/m_b automatically arising from its structure. The model below a scale 1016\sim 10^{16} GeV gives naturally rise just to the minimal supersymmetric standard model and therefore to the presently favored values for sin2θwsin^2 \theta_w and αs\alpha_s without fields in representations higher than the fundamental.Comment: 9 pages, LaTeX, UT-STPD-3-9

    Third Generation Effects on Fermion Mass Predictions in Supersymmetric Grand Unified Theories

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    Relations among fermion masses and mixing angles at the scale of grand unification are modified at lower energies by renormalization group running induced by gauge and Yukawa couplings. In supersymmetric theories, the bb quark and τ\tau lepton Yukawa couplings, as well as the tt quark coupling, may cause significant running if tanβ\tan \beta, the ratio of Higgs field expectation values, is large. We present approximate analytic expressions for the scaling factors for fermion masses and CKM matrix elements induced by all three third generation Yukawa couplings. We then determine how running caused by the third generation of fermions affects the predictions arising from three possible forms for the Yukawa coupling matrices at the GUT scale: the Georgi-Jarlskog, Giudice, and Fritzsch textures.Comment: phyzzx, 26 pp., 6 figures not included, e-mailable upon request, JHU-TIPAC-93000

    A study of the association of HLA DR, DQ, and complement C4 alleles with systemic lupus erythematosus in Iceland

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    To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldOBJECTIVE: To perform an exploratory analysis of the relative contribution of single MHC genes to the pathogenesis of systemic lupus erythematosus (SLE) in a homogenous white population. METHODS: MHC class II alleles and C4 allotypes were determined in 64 SLE patients and in ethnically matched controls. HLA-DR and DQ typing was performed by polymerase chain reaction amplification with sequence specific primers. C4 allotypes were determined by agarose gel electrophoresis. RESULTS: The frequency of C4A*Q0 was significantly higher in patients than in controls (46.9% v 25.3%, p = 0.002). HLA-DRB1, DQA1, and DQB1 alleles in the whole group of SLE patients were not significantly different from those of controls. On the other hand increase in DRB1*03 was observed in the group of patients with C4A*Q0, as compared with patients with other C4A allotypes (p = 0.047). There was no significant correlation between severe and mild disease, as judged by the SLEDAI, and HLADR, DQ alleles and comparing the patients with C4A*Q0 with those with other C4A allotypes there was no significant difference regarding clinical manifestations. CONCLUSION: The results are consistent with the argument that C4A deficiency contributes independently to susceptibility and the pathogenesis of SLE. C4A*Q0 in SLE patients in Iceland shows weaker linkage disequilibrium with DR3 genes than reported in most other white populations and emphasises the role of ethnicity

    A New Technique for Detecting Supersymmetric Dark Matter

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    We estimate the event rate for excitation of atomic transition by photino-like dark matter. For excitations of several eV, this event rate can exceed naive cross-section by many orders of magnitude. Although the event rate for these atomic excitation is smaller than that of nuclear recoil off of non-zero spin nuclei, the photons emitted by the deexcitation are easier to detect than low-energy nuclear recoils. For many elements, there are several low-lying states with comparable excitation rates, thus, spectral ratios could be used to distinguish signal from background.Comment: 6 pages plain te

    Predictions for Constrained Minimal Supersymmetry with Bottom-Tau Mass Unification

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    We examine the Constrained Minimal Supersymmetric Standard Model (CMSSM) with an additional requirement of strict b - tau unification in the region of small tan(beta). We find that the parameter space becomes completely limited below about 1 TeV by physical constraints alone, without a fine-tuning constraint. We study the resulting phenomenological consequences, and point out several ways of falsifying the adopted b - tau unification assumption. We also comment on the effect of a constraint from the non-observation of proton decay.Comment: Michigan preprint UM-TH-94-03, LaTeX, 18 pages with inline figures (figures included in uuencoded file). Complete PS file also available by anonymous FTP to williams.physics.lsa.umich.edu in /pub/preprints/UM-TH-94-03.ps.Z or by e-mailing reques

    Twist Deformations of the Supersymmetric Quantum Mechanics

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    The N-extended Supersymmetric Quantum Mechanics is deformed via an abelian twist which preserves the super-Hopf algebra structure of its Universal Enveloping Superalgebra. Two constructions are possible. For even N one can identify the 1D N-extended superalgebra with the fermionic Heisenberg algebra. Alternatively, supersymmetry generators can be realized as operators belonging to the Universal Enveloping Superalgebra of one bosonic and several fermionic oscillators. The deformed system is described in terms of twisted operators satisfying twist-deformed (anti)commutators. The main differences between an abelian twist defined in terms of fermionic operators and an abelian twist defined in terms of bosonic operators are discussed.Comment: 18 pages; two references adde

    On the Unification of Couplings in the Minimal Supersymmetric Standard Model

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    The unification of gauge and Yukawa couplings within the minimal supersymmetric standard model is studied at the two loop level. We derive an expression for the effective scale, TSUSYT_{SUSY}, which characterizes the supersymmetric particle threshold corrections to the gauge couplings, and demonstrate that TSUSYT_{SUSY} is only slightly dependent on the squark and slepton masses, and strongly dependent on the Higgsino masses as well as on the mass ratio of the gauginos of the strong and weak interactions. Moreover, the value of the top quark Yukawa coupling necessary to achieve the unification of bottom and tau Yukawa couplings is also governed by TSUSYT_{SUSY}, and it yields predictions for the top quark mass which are close to the quasi infrared fixed point results associated with the triviality bounds on this quantity. From the requirement of perturbative consistency of the top quark Yukawa sector of the theory, we obtain constraints on the allowed splitting of the supersymmetric spectrum, which, for certain values of the running bottom quark mass, are stronger than those ones coming from the experimental constraints on the strong gauge coupling.Comment: 40 pages, MPI-Ph/93-1
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