We present a scale invariant extension of the standard model with a new QCD-like strong interaction in the hidden sector. A scale Λ(H) is dynamically generated in the hidden sector by dimensional transmutation, and chiral symmetry breaking occurs in the hidden sector. This scale is transmitted to the SM sector by a real singlet scalar messenger S and can trigger electroweak symmetry breaking. Thus all the mass scales in this model arise from the hidden sector scale Λ(H), which has quantum mechanical origin. Furthermore, the lightest hadrons in the hidden sector are stable by the flavor conservation of the hidden sector strong interaction, and could be the cold dark matter (CDM). We study collider phenomenology, relic density, and direct detection rates of the CDM of this model.

We consider a hidden sector with a vectorlike confining gauge theory like QCD with N h,c colors and N h,f light quarks Q h in the hidden sector. Then a scale Λ H would be generated by dimensional transmutation, and chiral symmetry breaking occurs in the hidden sector. This scale Λ H can play a role of the SM Higgs mass parameter, triggering electroweak symmetry breaking (EWSB). Furthermore the lightest mesons in the hidden sector is stable by flavor conservation of the hidden sector strong interaction, and could be a good cold dark matter (CDM). We study collider phenomenology, and relic density and direct detection rates of the CDM of this model.

We consider a scenario where a supersymmetric model has multiple dark matter particles. Adding a U (1) ′ gauge symmetry is a well-motivated extension of the Minimal Supersymmetric Standard Model (MSSM). It can cure the problems of the MSSM such as the µ-problem or the proton decay problem with high-dimensional lepton number and baryon number violating operators which Rparity allows. An extra parity (U -parity) may arise as a residual discrete symmetry after U (1) ′ gauge symmetry is spontaneously broken. The Lightest U -parity Particle (LUP) is stable under the new parity becoming a new dark matter candidate. Up to three massive particles can be stable in the presence of the R-parity and the U -parity. We numerically illustrate that multiple stable particles in our model can satisfy both constraints from the relic density and the direct detection, thus providing a specific scenario where a supersymmetric model has well-motivated multiple dark matters consistent with experimental constraints. The scenario provides new possibilities in the present and upcoming dark matter searches in the direct detection and collider experiments.

We study the possibility of discovering neutral scalar Higgs bosons in the U (1) ′extended supersymmetric standard model (USSM) at the CERN Large Hadron Collider (LHC), by examining their productions via the exotic quark loop in the gluon fusion process at leading order. It is possible in some parameter region that the neutral scalar Higgs bosons may have stronger couplings with the exotic quarks than with top quark. In this case, the exotic quarks may contribute more actively than top quark in productions of the neutral scalar Higgs bosons in the gluon fusion process. We find that there is indeed some parameter region in the USSM that support our speculations.

We present the phenomenology of antisymmetric rank-2 tensor unparticle operator O µν U ,A with scaling dimension d U . We consider the physical effects of operator O µν U ,A in Z 0 boson invisible decays Z 0 → U , Z 0 → bb channel, the electroweak precision observable S parameter, and the muon anomalous magnetic dipole moment. The Z 0 boson invisible decay gives a very stringent constraint in the (Λ U , M U ) plane, and only small r ≡ Λ U /M U < ∼ 0.1 is favored, when Λ U is order of several 100 GeV. When the phenomenological parameter µ, which parameterizes the scale invariance breaking, goes to 0, the S parameter and the muon (g − 2) diverge for 1 < d U < 2, while for non-zero µ, there will be constraints on (Λ U , M U ) which are more stringent than those obtained from collider experiments.