Session S11: Searches I

Search for Large Extra Spatial Dimensions in Events with a Photon and Missing Transverse Energy Using the D0 Detector

A final state containing a high $E_{T}$ photon and large missing transverse energy, although challenging experimentally, is quite interesting. Observation of an excess of such events compared to the Standard Model prediction could indicate, for example, existence of large extra spatial dimensions or anomalous ZZ$\gamma$ couplings. We will present the latest DZero results for this final state.   

CMS Search Plans for Dijet Resonances

New particles decaying to two partons can produce large dijet resonance signals at the LHC. The dijet mass distribution at CMS is sensitive to the rate of strongly produced resonances in a previously unexplored mass region. The expected dijet mass resolution at CMS is presented. The dijet ratio is sensitive to the decay angular distribution of dijet resonances, and therefore also to resonance spin. The optimum pseudorapidity interval for these measurements is discussed. The expected sensitivity using the dijet mass distribution and the dijet ratio with 100 pb$^{-1}$ of integrated luminosity is explored.   

CMS Search Plans for Contact Interactions Using Jets

Contact interactions arising from quark compositeness or other sources of physics beyond the standard model can produce large signals in jet events at LHC. The inclusive jet transverse momentum distribution is sensitive to an unexplored contact interaction scale $\Lambda$ with only 10 pb$^{-1}$ of integrated luminosity. Studies of the jet response versus pseudorapidity at CMS are presented. Uncertainties due to jet energy scale and parton distributions of the proton are discussed. With the dijet ratio CMS will search for the affects of a contact interaction in dijet angular distributions. Sensitivity to $\Lambda$ for integrated luminosities of 10 pb$^{-1}$, 100 pb$^{-1}$, and 1 fb$^{-1}$ are presented.   

Large Extra dimensions in the ATLAS detector

Large Extra dimensions in the ATLAS detector E. Fullana Argonne National Laboratory One of the open questions in the Standard Model is the seventeen orders of magnitude difference between the Planck scale and the electroweak scale. Theories of large extra dimensions explain the apparent weakness of gravitational interaction by the leakage of gravitons through extra spatial dimensions. These theories predict that gravity could play an important role at colliders when the energy scale is above the TeV scale. The ATLAS experiment is one of the four experiments at the LHC, which is the new 14 TeV proton proton collider being commissioned at CERN (Geneva, Switzerland). The determination of the jet energy scale and its uncertainty is a milestone along the path to discovery of such signals. We describe the process to determine and validate the jet energy scale and its effect on extra dimensions signatures.   

Search for High-Mass Resonances Decaying into Leptons of Different Flavor

We present a search for high-mass resonances decaying into two leptons of different flavor: $e\mu$, $e\tau$ and $\mu\tau$. These resonances are predicted by several models beyond the Standard Model, such as the R-parity-violating MSSM. The search is based on 1~$\rm fb^{-1}$ of Tevatron Run II data collected with the CDF detector at $\sqrt{s}$ = $1.96$ TeV in proton anti-proton collisions.   

Search for a New Massive Boson $Z'$ with Di-muon Data at CDF

We present a measurement of the Drell-Yan mass spectrum at high energies in the dimuon channel using 2/fb of proton-antiproton collision data taken with the CDF II detector at a centre of mass energy of 1.96 GeV. We examine this mass spectrum for any excesses over Standard Model predictions and to search for new neutral massive bosons such as Z' decaying to two muons.   

Search for non-standard model top antitop resonance production in the all-hadronic channel at CDF

We present the first result of a novel search for resonant top-antitop pair production and subsequent decay in the all-hadronic channel. We examine the top-antitop invariant mass spectrum observed in CDF II data from 1.9 TeV proton-antiproton collisions at Fermilab Tevatron. A narrow resonance state decaying to a top-antitop pairs will appear as a ``bump'' in the observed mass spectrum. We apply a powerful reconstruction technique where the observed event kinematics are constrained according to the full standard model top-antitop production and decay matrix element. This technique provides excellent mass resolution. Also, probability densities from the per-event matrix element calculation are used as discriminants to reduce and control the large backgrounds of the all-hadronic channel.