Experiments were carried out in an axisymmetric turbulent jet from 2 to 6 diameters downstream at exit Reynolds numbers of 78 400, 117 600, and 156 800. Data were collected using the 138 hot-wire probe constructed by Citriniti & George (2000). The proper orthogonal decomposition (POD) was then applied to a double Fourier transform in time and azimuthal direction of the two-point velocity correlation tensor. Azimuthal mode-0, which dominated the dynamics at $x/D\,{=}\,3$ in the previous experiments, dies off rapidly downstream towards a non-zero value. For the higher azimuthal modes, the peak shifts from mode-6 towards lower azimuthal mode numbers with increasing downstream distance, until the peak is at mode-2 by the end of the potential core. The POD eigenspectra collapse in similarity variables for the mixing layer at all downstream positions, and are nearly independent of Reynolds number. Reconstruction of the full-field streamwise velocity component using the dominant POD modes shows clearly the evolution of the flow with downstream position, from ‘volcano-type’ eruptions at 2 to 3 diameters downstream to a ‘propeller-like’ pattern where the number of blades diminishes downstream.

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 perform a model independent analysis on qq → tt using an effective lagrangian with dim-6 four-quark operators, and derive necessary conditions on new physics that are consistent with the tt production cross section and the forward-backward (FB) asymmetry (AFB) measured at the Tevatron. We also propose a new FB spin-spin correlation that is strongly correlated with the AFB, and discuss possible new physics scenarios that could generate such dim-6 operators.

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