Session X12: Searches III

Search for Charged Massive Stable Particles Using Data from D0

We report on a search for charged massive stable particles (CMSPs) by the D0 Experiment at Fermilab's Tevatron. CMSPs are predicted in many theories beyond the Standard Model. Time-of-flight information was used in the search for pair-produced CMSPs, 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 data taken by the DO detector in Run II corresponding to an integrated luminosity of 1.1 fb~$^{-1}$. Limits on the production of stable stau leptons, gaugino-like charginos, and higgsino-like charginos are presented.   

Identification of Heavy Stable Charged Particles at the CMS Experiment

Heavy Stable Charged Particles (HSCPs) are predicted by a number of different supersymmetric models, and would be observable using the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC). An HSCP produced at the LHC would have momentum on the order of several hundred GeV, but would travel slowly because of its large mass. This makes it possible to obtain the mass of an HSCP using velocity measurements from the silicon tracker, muon drift tubes, muon cathode strip chambers, and/or the electromagnetic calorimeter. Two methods of determining the velocity of an HSCP will be discussed: $dE/dx$ measurement and time-of-flight analysis.   

Heavy Stable Charged Particle Physics and Discovery Potential at CMS

Heavy Stable Charged Particles are predicted by various Super Symmetry and Extra Dimension models. Experimentally, they can be identified by exploiting their unique signature: a high momentum particle of the order of a hundred GeV with a low relativistic $\beta$ value. In this talk, we will describe four models predicting different types of Heavy Stable Charged Particles and use them as benchmarks for the search analysis strategy at CMS experiment. We will also show their potential reach at CMS with data based on 100 pb$^{-1}$ and 1 fb$^{-1}$ of integrated luminosity.   

Discriminating Supersymmetry and Black Holes at the Large Hadron Collider

We assess the distinguishability between supersymmetry and black hole events at the Large Hadron Collider. Black hole events are simulated with the \texttt{CATFISH} black hole generator. Supersymmetry simulations use a combination of \texttt{PYTHIA} and \texttt{ISAJET}. Our study, based on event shape variables, visible and missing momenta, and analysis of dilepton events, shows that supersymmetry and black hole events at the LHC can be easily discriminated.   

Accelerator Mass Spectrometry Search for Strangelets in Lunar Soil

The theoretical existence of Strange Quark Matter (SQM) with similar amounts of up, down and strange quarks in one single hadronic bag has been postulated for over two decades. A wide range of experimental searches for strangelets (small lumps of SQM with baryon number less than $10^6$) have been conducted but all failed to give a definite answer to the existence of SQM. Our experiment searches for strangelets in lunar soil. Cosmic ray flux deposits strangelets on the Moon with a predicted concentration (one strange oxygen per $10^{16}$ to $10^{17}$ normal oxygen atoms) of $10^5$ times higher than that on Earth. The lunar soil sample is analyzed using accelerator mass spectrometry through the tandem Van-de-Graaff accelerator at Yale University. The accelerator together with our own designed detection system enables us to identify strangelets at a level of less than 1 per $10^{17}$ atoms. We have covered mass range 48-55 amu, with a step size of a quarter amu each scan. In the next three months, we are planning to scan another 10 amu or so starting from 55 amu.   

Global Search for New Electroweak-Scale Physics at CDF

A global search for new electroweak-scale physics at the Fermilab Tevatron is presented. With no particular new physics scenario being favored, we adopt a search strategy focusing on discrepancies with respect to the standard model prediction in over three hundred exclusive final states. This analysis of the CDF Run II high-$p_T$ data represents the most encompassing single search for new physics at the energy frontier.   

A Model Independent Search Using D0 Run II Data

We present a status report on model independent searches at the D0 experiment using a subset of data from RunIIa of the Tevatron containing high-$p_{T}$ objects. The data is divided into non- overlapping final states and carefully compared to the Standard Model prediction. This approach complements model-dependent searches by scanning systematically across many final states some which would otherwise be considered only within the context of very specific models or not considered at all. Once all effects due to SM implementation, detector modeling and statistical fluctuations are taken into account, we search for deviations which could indicate the presence of physics beyond the Standard Model.   

Search for Technicolor Particles Produced in Association with a W Boson at CDF

We present a search for the technicolor particles ($\rho_{T} \to \pi_{T} + W$) decaying to $b\bar{b}$ and in association with W boson in $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV. A dataset corresponding to an integrated luminosity of 1.9fb$^{-1}$ is used in this analysis. Selected events have one high-$p_{T}$ electron or muon, missing $E_{T}$ and two b-jets. In order to improve the sensitivity we make use of b-tagging techniques to identify and categorized events with one or two b-tagged jets. We set a 95\% confidence level upper limit on the production cross section times branching ratio as a function of the mass of the technicolor particles involved in the interaction.