String models Calabi-Yau compactification of heterotic string theory Orbifold compactification of heterotic string theory Grand Unified Theory(GUT) can be realized naturally through the elegant Es breaking chain: Es D E6 D SO(10)D SU(5) D-brane models on Type Il orientifolds N stacks of D-branes gives us U(N) gauge symmetry: Pati-Salam Models Free fermionic string model building Realistic models with clean particle spectra can only be constructed t the Kac-Moody level one: the Standard-like models, Pati-Salam mode els, and flipped SU(5) models
F-Theory Model Building e The models are constructed locally, and then the gravity should decoupled, i.e., MGUT/MPI is a small number The SU(5)and SO(10) gauge symmetries can be broken by the U(1)y and U(1)x/U(1)B-L fluxes Gauge mediated supersymmetry breaking can be realized via instanton effects. Gravity mediated supersymmetry breaking predicts the gaugino mass relation All the sm fermion Yuakwa couplings can be generated in the SU(5) and SO(10)models The doublet-triplet splitting problem, proton decay problem, A problem as well as the SM fermion masses and mixing problem can be solved
BICEP The inflation scale is the gut scale The inflaton potential non-renormalized theorem for superpotential °M^2{EW}simM{inu}H
BICEP2 • The inflation scale is the GUT scale. • The inflaton potential: non-renormalized theorem for superpotential. • M^2_{EW} \sim M_{\nu} H
II. SUSY EW Fine-Tuning problem Higgs boson mass LHC SUSY Search Fine-Tuning problem
II. SUSY EW Fine-Tuning Problem • Higgs Boson Mass • LHC SUSY Search • Fine-Tuning Problem
The Lightest CP-Even Higgs Boson mass Stops: Enhancing Higgs mass 惠· Tree-levelupper bound:z- boson mass mz=917GeV In the Mssm, Higgs quatic coupling at tree-level is determined by Ew gauge couplings t . Correct the quartic coupling and enhance Higgs bosonmass mh= mz cos 28+ 3mn|1ogmn2≠+2/,x2 12m2 s .Stop maximal mixing relaxing the little hierachyproblem Without large stop mixing, we need /m 10 TeV stops, rendering afine-tuning /mz~0.01% Stop maximalllarge mixing can improves it by about two orders X2=(4-u/tan)2≈6m2
• Stops: Enhancing Higgs mass •Correct the quartic coupling and enhance Higgs boson mass •Stop maximal mixing relaxing the little hierachy problem •Without large stop mixing, we need •10 TeV stops, rendering a fine-tuning / ~ / ~ 0.01% 2 2 2 2 mH mZ m~ mZ u t − •Tree-level upper bound: Z-boson mass mZ = 91.7 GeV •In the MSSM, Higgs quatic coupling at tree-level •is determined by EW gauge couplings 2 2 2 6 ~ ( / tan ) t Xt = At − m •Stop maximal/large mixing can improves it by about two orders •The Lightest CP-Even Higgs Boson Mass