Two jets and missing ETE_T signature to determine the spins of the new particles

We consider the spin determination of new colored particles in the missing energy plus jets channel at the early stage of LHC. We use a three site moose model to describe the low energy Lagrangian of all same spin partner (LHT or UED like) models and check the gauge invariance of the amplitude. For the benchmark production and decay channel $pp \rightarrow U^{(R)} U^{(R)} \rightarrow u u B_H B_H$, in contrast to those in supersymmetric models, there are spin correlations which affect the polar and azimuthal angle distributions of the quarks from the heavy partner $U^{(R)}$ decay. We show such effects would be visible in the $E_{\rm T miss} / M_{\rm eff}$ distribution and the reconstructed azimuthal angle correlation using MAOS reconstruction.Comment: 20 pages, 9 figure

Dark Matter and Collider Physics in Split-UED

Kaluza-Klein dark matter is an attractive weakly interacting massive particle in universal extra dimension model. In the recent extension "split-UED", annihilation of Kaluza-Klein dark matter with a mass range 600-1000 GeV provides excellent fits to the recently observed excesses in cosmic electron and positron fluxes of Pamela, ATIC and Fermi-LAT experiments. The cosmic gamma-ray flux in the same process can be significant around 300 GeV, thus can be observed or constrained by the forthcoming Fermi-LAT diffuse gamma-ray data. The collider signal at the LHC is the resonance in the dijets channels and the large missing energy in the missing energy plus jets.Comment: 3 pages, 6 figures, Talks given at 17th International Conference on Supersymmetry and the Unification of Fundamental Interactions (SUSY09), Boston, USA, 5-10 June 200

Prospects for Triple Gauge Coupling Measurements at Future Lepton Colliders and the 14 TeV LHC

The $WW$ production is the primary channel to directly probe the triple gauge couplings. We first analyze the $e^+ e^- \rightarrow W^+ W^-$ process at the future lepton collider, China's proposed Circular Electron-Positron Collider (CEPC). We use the five kinematical angles in this process to constrain the anomalous triple gauge couplings and relevant dimension six operators at the CEPC up to the order of magnitude of $10^{-4}$. The most sensible information is obtained from the distributions of the production scattering angle and the decay azimuthal angles. We also estimate constraints at the 14 TeV LHC, with both 300 fb$^{-1}$ and 3000 fb$^{-1}$ integrated luminosity from the leading lepton $p_T$ and azimuthal angle difference $\Delta \phi_{ll}$ distributions in the di-lepton channel. The constrain is somewhat weaker, up to the order of magnitude of $10^{-3}$. The limits on the triple gauge couplings are complementary to those on the electroweak precision observables and Higgs couplings. Our results show that the gap between sensitivities of the electroweak and triple gauge boson precision can be significantly decreased to less than one order of magnitude at the 14 TeV LHC, and that both the two sensitivities can be further improved at the CEPC.Comment: 36 pages, 5 figures, 8 tables, version to appear in JHE

Towards the fate of natural composite Higgs model through single t′t^\prime search at the 8 TeV LHC

We analyze the observational potential of single $t'$ production in both the $t^\prime \rightarrow bW$ and $t^\prime \rightarrow th$ decay channels at 8 TeV LHC using an integrated luminosity of 25 $\text{fb}^{-1}$. Our analysis is based on a simplified model with minimal coset $SO(5)/SO(4)$ in which the $t'$ is a singlet of the unbroken SO(4). The single $t'$ production, as a consequence of electroweak symmetry breaking, is less kinematically suppressed, associated with a light forward jet and has boosted decay products at the 8 TeV LHC. Therefore it provides the most promising channel in searching for a heavy $t'$. We have exploited the above kinematical features and used the jet substructure method to reconstruct the boosted Higgs in $th$ decay channel. It is shown that a strong constraint on the $t^\prime bW$ coupling ($g_{t^\prime bW}/g_{tbW,SM} < 0.2 \sim 0.3$) at the 95% C. L. can be obtained for $m_{t'} \subset (700, 1000)$ GeV.Comment: 22 pages, 8 figures, 5 tables, refs added in v

Disentangling Strong Dynamics through Quantum Interferometry

We present a new probe of strongly coupled electroweak symmetry breaking at the 14 TeV LHC by measuring a phase shift in the event distribution as a function of the decay azimuthal angles in massive gauge boson scattering. A large phase shift arises from an interference effect between the strongly interacting longitudinal modes and the transverse modes of the gauge bosons. We find that even very broad resonances of masses up to 900 GeV can be probed at 3$\sigma$ significance with a 3000 fb$^{-1}$ run of the LHC by using this technique. We also present the estimated reach for a future 50 TeV proton-proton collider.Comment: 6 pages, 4 figures. Revised introduction and more details added to discussion of results; results are unchanged. Version accepted by PR