分类： 物理学 >> 基本粒子与场物理学 提交时间： 2017-09-17
摘要： A pattern of quark mass hierarchy and CP violation within the framework of low energy supersymmetry is described. By assuming some discrete symmetry among the three families, the quarks of the third family obtain masses at tree level. The second family obtains masses radiatively at one-loop level due to the soft breaking of the family symmetry. At this level, the first family remains massless by some degeneracy conditions of the squarks. As a result of R-parity violation, the sneutrino vacuum expectation values are nonvanishing. CP violation occurs through the superweak sneutrino exchange. This picture is consistent with the experiments on the flavor changing neutral current.
分类： 物理学 >> 基本粒子与场物理学 提交时间： 2017-09-17
摘要： It is proposed that supersymmetry (SUSY) maybe used to understand fermion mass hierarchies.A family symmetry Z3L is introduced, which is the cyclic symmetry among the three generationSU(2) doublets. SUSY breaks at a high energy scale ∼ 1011 GeV. The electroweak energy scale∼ 100 GeV is unnaturally small. No additional global symmetry, like the R-parity, is imposed.The Yukawa couplings and R-parity violating couplings all take their natural values which are O(100 − 10−2). Under the family symmetry, only the third generation charged fermions get their masses. This family symmetry is broken in the soft SUSY breaking terms which result in a hierarchical pattern of the fermion masses. It turns out that for the charged leptons, the #28; mass is from the Higgs vacuum expectation value (VEV) and the sneutrino VEVs, the muon mass is due to the sneutrino VEVs, and the electron gains its mass due to both Z3L and SUSY breaking.The large neutrino mixing are produced with neutralinos playing the partial role of right-handed neutrinos. |Ve3| which is for #23;e − #23;#28; mixing is expected to be about 0.1. For the quarks, the third generation masses are from the Higgs VEVs, the second generation masses are from quantum corrections, and the down quark mass due to the sneutrino VEVs. It explains mc/ms, ms/me,md > mu and so on. Other aspects of the model are discussed.
分类： 物理学 >> 基本粒子与场物理学 提交时间： 2017-09-17
摘要： If supersymmetry (SUSY) is not for stabilizing the electroweak energy scale, what is it used for in particle physics? We propose that it is for flavor problems. A cyclic family symmetry is introduced. Under the family symmetry, only the #28; -lepton is massive due to the vacuum expectation value (VEV) of the Higgs field. This symmetry is broken by a sneutrino VEV which results in the muon mass. The comparatively large sneutrino VEV does not result in a large neutrino mass due to requiring heavy gauginos. SUSY breaks at a high scale ∼ 1013 GeV. The electroweak energy scale is unnaturally small. No additional global symmetry, like the R-parity, is imposed. Other aspects of the model are discussed.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-09-17
摘要： A supersymmetric model with gauge symmetry G1 × G2, where Gi = SU(3)i × SU(2)i × U(1)i, is constructed within the framework of gauge me-diated supersymmetry breaking. At the energy scale ∼ (10−100) TeV wherem the gauge symmetry breaks down to the Standard Model (SM), G1 is strong and G2 is weak. The observed gauge coupling constant unification of the SM is attributed to that of G2. The messenger fields and Higgs fields just sat-isfy the condition that makes G2 a realization of strong unification. The SMgauginos are predicted to be generally heavier than the sleptons and squarks.
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