Session T11: Miscellaneous Searches II

Search for Neutral Supersymmetric Higgs Bosons in b$\tau\tau$ Final States

We report preliminary results in a search for neutral Higgs bosons via the channel $p\bar{p}\to h+b \to\tau+\tau+b$ using 2 fb$^{-1}$ of data collected by the D0 experiment at the Tevatron. One tau is required to decay to a muon and a pair of neutrinos, and the other one to decay hadronically. The result is interpreted in terms of upper limits on the Higgs boson production cross section in supersymmetric models.   

A New Algorithm for Measuring the Energy of Hadronically Decaying Tau Leptons

We present a new technique for the accurate energy measurement of hadronically decaying tau leptons. This technique has been developed for use at the CDF experiment at the Tevatron. It is based on the particle flow algorithm complemented with a likelihood-based technique for separating contributions of overlapping depositions of spatially close particles. Based on Monte Carlo studies, this new approach is expected to improve the accuracy of the measurement by approximately a factor of two. In addition to superior energy resolution, this technique provides a direct estimate of the uncertainty on the energy measurement of individual tau candidates. While important in itself, this latter feature can serve as a powerful identification tool in distinguishing hadronically decaying tau leptons from jet and light lepton backgrounds. This new technique is expected to significantly improve the sensitivity of the $h \to \tau \tau$ search at the Tevatron.   

A Monte Carlo Study of NMSSM Higgs Searches at the Large Hadron Collider

We present a Monte Carlo study of the potential to observe Higgs bosons in the Next-to-Minimal SuperSymmetric Standard Model (NMSSM) at the Large Hadron Collider. We consider Higgs bosons that decay predominantly into a pair of light pseudoscalars (axions), which are kinematically constrained to decay into four tau leptons. The four-tau final state is important as it may arise in many models of new physics beyond the standard model where new light states form the dominant decay modes for the Higgs Boson. The analysis we present is also applicable to many other models with extended Higgs sectors. The study has been confined to the axion mass range 2m$_{\tau}$ $<$ m$_a$ $<$ 2m$_b$ so as to ensure that axions decay preferentially into tau leptons. This mass range provides a distinctive signal especially when the taus decay to electrons and muons.   

Search for New Physics in the $\gamma + b + j + \not\!\!{E_{T}}$ + X Final State

Given the large number of predicted and as-yet-unknown models of new physics, the first signals of new processes may appear in any final state. In this study we analyse the $\gamma+b+jet+\not\!\!{E_{T}}$ state. Without the constraints of a particular model prediction, we examine the kinematics of the events and compare to the standard model prediction. We use 1.8 fb$^{-1}$ of data collected by CDF at the Tevatron at $\sqrt s = 1.96$ TeV.   

Search for Anomalous Production of $\gamma$ + Jets + $\not\!\!{E_{T}}$

Many new physics models predict mechanisms that could produce a $\gamma$ and jets signature. We search in the $\gamma$ + jets and $\gamma$ + jets + $\not\!\!{E_{T}}$ channels, independent of any model, for new physics using 2~fb$^{-1}$ of CDF Run II data collected at the Fermilab Tevatron from $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV. A variety of techniques are applied to estimate the standard model expectation and non-collision backgrounds. We examine several kinematic distributions including $\not\!\!{E_{T}}$, $\Sigma E_T$, and invariant mass for discrepancies with respect to the standard model.   

Search for Supersymmetry in the $\not\!\!{E_{T}}$ + b-jet Signature at CDF

Using data collected with the CDF detector in Run II of the Tevatron, we search events containing two or more jets and missing transverse energy for the presence of physics beyond the Standard Model. At least one of the jets is required to be tagged as originating from a heavy-flavour quark. The analysis is optimized for sensitivity of the supersymmetric partner of the bottom quark produced from gluino decays. Preliminary results are presented, along with future plans for improvements in searches with this signature.   

Measurement of $Z \gamma$ Production at CDF

We present results from studies of photons produced in association with $Z$ bosons in $p\overline{p}$ collisions at $\sqrt{s} =$ 1.96 TeV at the Tevatron. Tri-linear gauge couplings are fundamental predictions of the Standard Model, and studying these couplings provides a sensitive test for non-Standard Model interactions. Here we compare measurements using 2~$fb^{-1}$ of CDF data with Standard Model predictions and predictions from models containing anomalous couplings.   

Search for a scalar top quark at CDF

For some regions of SUSY parameter space it is conceivable that the supersymmetric partner of the top quark (stop squark) could be the lightest squark, and could actually be less massive than the standard model top quark. Also, depending on the mass hierarchy of SUSY, a stop squark event might look nearly identical in the detector to that of a top quark event. The presence of such a light stop squark could easily go unnoticed due to the much lower production cross section of the scalar stop squark, as compared to the fermionic top quark. We present a search for the stop squark at CDF in the mass range 135 to 170 GeV. We look in the dilepton decay channel, that is a final state with two leptons, at least two jets, and large missing transverse energy. Using a weighting technique, we reconstruct the mass of the under-constrained stop squark events, and use the reconstructed mass to discriminate stop squark events from backgrounds. This new reconstruction technique provides a promising avenue to search for the stop squark.   

Single Top Production in Unparticle Physics

We study the single production of top quarks in $e^+e^-, ep$ and $pp$ collisions in the context of unparticle physics through the Flavor Violating (FV) unparticle vertices and compute the total cross sections for single top production as functions of scale dimension $d_{\mathcal{U}}$. We find that among all, LHC is the most promising facility to probe the unparticle physics via single top quark production processes.