Natural solution to the supersymmetry Electroweak Fine-Tuning Problem Tianjun Li Institute of Theoretical Physics, Chinese Academy of Sciences Yellow Mountain, May 9, 2014
Natural Solution to the Supersymmetry Electroweak Fine-Tuning Problem Tianjun Li Institute of Theoretical Physics, Chinese Academy of Sciences Yellow Mountain, May 9, 2014
Outline ·I. Introduction II. The SUSY ew Fine-Tuning problem I. The Mssm with the Heavy LsP ⅣV.No- Scale f-su(5) V. General Natural Solution ⅵI. Summary
Outline • I. Introduction • II. The SUSY EW Fine-Tuning Problem • III. The MSSM with the Heavy LSP • IV. No-Scale F-SU(5) • V. General Natural Solution • VI. Summary
I ntroduction Standard Model: Fine-tuning problems: cosmological constant problem; gauge hierarchy problem; strong CP problem: SM fermion masses and mIxIngs. Aesthetic problems: Interaction and fermion unification; gauge coupling unification; charge quantization; too many parameters;
I. Introduction
Gauge Hierarchy problem C=AHff+AsIHPISI 入s △mH 8724V+16724UV f H H (b)
Gauge Hierarchy Problem 4
Solutions: e Techicolor: the higgs is a condensation of new fermions. Point: no amental scalar Larger extra dimension(s) Arkani-Hamed-Dimopoulos-Dvali (ADD)and Randall-Sundrum(RS). Point: the high-dimensional Planck scale is close to the tev ● Supersymmetry. e Little higgs model effective theories for compositeness. the anthropic solution, etc
Supersymmetric Standard Model: Solving the gauge hierarchy problem e Gauge coupling unification Radiatively electroweak symmetry breakin arge top quark mass e Natural dark matter candidates Neutralino, sneutrino, gravitino Electroweak baryogenesis Electroweak precision: R parity
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Gauge Coupling Unification 60 50 40 SU(2) 30 20F 10 sU(3) 4681012141618 Log(Q/GeV
Gauge Coupling Unification 7
Problems in the mssm u problem uhud Little hierarchy problem Fine-tuning for the lightest CP even Higgs mass e CP violation and eDms FCNC Dimension-5 proton decays
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The Grand Unified Theories: SU(5), and SO(10), etc Unification of the gauge interactions, and unifications of the SM fermions Charge quantization Gauge coupling unification in the MSSM, and Yukawa unification 犹t=b=y Radiative electroweak symmetry breaking due to the large top quark Yukawa coupling e Weak mixing angle at weak scale Mz Neutrino masses and mixings by seesaw mechanism
Problems Gauge symmetry breaking Doublet-triplet splitting problem Higgs particles do not form complete GUT multiplet at low energy ● Proton decay problen Fermion mass problem GUT relation me/mu=md/ms