Session R9: Mini-Symposium on Searches I

Physics Beyond the Standard Model

I will present an overview of searches for non-standard model phenomena. The focus will be on the recent results from Fermilab Tevatron, using 1--3~fb$^{-1}$ of data collected with the CDF and D0 detectors. Both signature-based searches and searches driven by models will be discussed. Models include supersymmetry, extra dimension, leptoquark, extra heavy gauge bosons, technicolor, {\it etc.}.   

The Dijet Mass Spectrum and a Search for Quark Compositeness at CDF

The standard model (SM) gives a good description of nature in terms of the fundamental fermions and their interactions via gauge bosons. However, the SM is not expected to be a complete theory. For example, it does not explain the number of fermion families or their mass hierarchy. It also does not provide a unified description of all gauge symmetries. Compositeness models postulate constituents of the SM fermions and new strong dynamics that bind these constituents. We search for quark compositeness by measuring dijet mass differential cross section in a few regions of rapidity magnitude ($|y|$) using about $3$ {$\rm fb {}^{-1}$} of data collected by the CDF experiment. The signal is expected in the region with small $|y|$.   

Search for charged massive long-lived particles at D0

We report on a new search for charged massive long-lived particles (CMLLP) by the D0 Experiment at Fermilab's Teva- tron. CMLLP are predicted in many theories beyond Standard Model. Time-of-flight information was used in the search for pair-produced CMLLPs, based on the signature of two particles, reconstructed as muons, with speed and invariant mass inconsistent with beam-produced muons. The analysis was done with the data taken by D0 detector in Run II cor- responding to an integrated luminosity of ~3 fb$^{-1}$. Limits on the pair production of CMLLPs are presented quasi-model independently.   

Search for scalar top decaying into charm and neutralino at CDF

Using the CDF detector in the Run II of the Tevatron, we have analyzed events containing two or more jets and missing transverse energy in order to look for the presence of new physics. At least one of the jets was required to be tagged as originating from a heavy-flavor quark in order to enhance the presence of c-jets. The analysis was optimized for the search for a scalar top decaying into charm and neutralino. Preliminary results will be presented as well as future plans for the search for a light scalar top in this channel.   

Setting Limits on Gauge Mediated Supersymmetry Breaking Models with Photons at CDF

Models of supersymmetry predict new heavy, neutral particles, known as a neutralino, that can decay to a photon and the lightest supersymmetric particle, the gravitino. We present a search for these particles in proton anti-proton collisions at $\sqrt{s}$=1.96 TeV at the Collider Detector at Fermilab. After years of data taking we find no evidence for this process and set the world's best limits on models of Gauge Mediated Supersymmetry Breaking.   

Search for trilepton SUSY signal at CDF

The production of chargino-neutralino and their subsequent leptonic decay is one of the most promising supersymmetry (SUSY) signatures at the Tevatron collider. We present a complete CDF search for trileptons and missing transverse energy associated with this process. To increase our sensitivity to SUSY signals (or any other new phenomena) we include low-pt electrons and muons (pT$>$5 GeV/c), low dilepton mases (Mll$>$10 GeV/c$^2$), forward leptons ($|\eta|>$1), loose leptons (isolated tracks that do not pass ordinary lepton selection) and tau-jets from hadronic tau decays. Special care is taken for the light-flavor and heavy-flavor QCD background that is significant in some of the kinematic regions we explore.