Standard model explanation of a CDF dijet excess in Wjj

We demonstrate the recent observation of a peak in the dijet invariant mass of the Wjj signal observed by the CDF Collaboration can be explained as the same upward fluctuation observed by CDF in single-top-quark production. In general, both t-channel and s-channel single-top-quark production produce kinematically induced peaks in the dijet spectrum. Since CDF used a Monte Carlo simulation to subtract the single-top backgrounds instead of data, a peak in the dijet spectrum is expected. The D0 Collaboration has a small upward fluctuation in their published t-channel data; and hence we predict they would see at most a small peak in the dijet invariant mass spectrum of Wjj if they follow the same procedure as CDF.Comment: 3 pg., 2 figs, revtex, minor clarifications, to appear in Phys. Rev.

Searches for Physics Beyond the Standard Model at Colliders

All experimental measurements of particle physics today are beautifully described by the Standard Model. However, there are good reasons to believe that new physics may be just around the corner at the TeV energy scale. This energy range is currently probed by the Tevatron and HERA accelerators and selected results of searches for physics beyond the Standard Model are presented here. No signals for new physics have been found and limits are placed on the allowed parameter space for a variety of different particles.Comment: Proceedings for 2007 Europhysics Conference on High Energy Physics, Manchester, July 200

Prompt Decays of General Neutralino NLSPs at the Tevatron

Recent theoretical developments have shown that gauge mediation has a much larger parameter space of possible spectra and mixings than previously considered. Motivated by this, we explore the collider phenomenology of gauge mediation models where a general neutralino is the lightest MSSM superpartner (the NLSP), focusing on the potential reach from existing and future Tevatron searches. Promptly decaying general neutralino NLSPs can give rise to final states involving missing energy plus photons, Zs, Ws and/or Higgses. We survey the final states and determine those where the Tevatron should have the most sensitivity. We then estimate the reach of existing Tevatron searches in these final states and discuss new searches (or optimizations of existing ones) that should improve the reach. Finally we comment on the potential for discovery at the LHC.Comment: 41 pages, minor changes, added refs and discussion of previous literatur

Measurements of the Production, Decay and Properties of the Top Quark: A Review

With the full Tevatron Run II and early LHC data samples, the opportunity for furthering our understanding of the properties of the top quark has never been more promising. Although the current knowledge of the top quark comes largely from Tevatron measurements, the experiments at the LHC are poised to probe top-quark production and decay in unprecedented regimes. Although no current top quark measurements conclusively contradict predictions from the standard model, the precision of most measurements remains statistically limited. Additionally, some measurements, most notably the forward-backward asymmetry in top quark pair production, show tantalizing hints of beyond-the-Standard-Model dynamics. The top quark sample is growing rapidly at the LHC, with initial results now public. This review examines the current status of top quark measurements in the particular light of searching for evidence of new physics, either through direct searches for beyond the standard model phenomena or indirectly via precise measurements of standard model top quark properties

A Fast Track towards the `Higgs' Spin and Parity

The LHC experiments ATLAS and CMS have discovered a new boson that resembles the long-sought Higgs boson: it cannot have spin one, and has couplings to other particles that increase with their masses, but the spin and parity remain to be determined. We show here that the `Higgs' + gauge boson invariant-mass distribution in `Higgs'-strahlung events at the Tevatron or the LHC would be very different under the J^P = 0+, 0- and 2+ hypotheses, and could provide a fast-track indicator of the `Higgs' spin and parity. Our analysis is based on simulations of the experimental event selections and cuts using PYTHIA and Delphes, and incorporates statistical samples of `toy' experiments.Comment: 18 pages, 9 pdf figure

Extracting Muon Momentum Scale Corrections for Hadron Collider Experiments

We present a simple method for the extraction of corrections for bias in the measurement of the momentum of muons in hadron collider experiments. Such bias can originate from a variety of sources such as detector misalignment, software reconstruction bias, and uncertainties in the magnetic field. The two step method uses the mean for muons from $Z\to \mu\mu$ decays to determine the momentum scale corrections in bins of charge, $\eta$ and $\phi$. In the second step, the corrections are tuned by using the average invariant mass of $Z\to \mu\mu$ events in the same bins of charge $\eta$ and $\phi$. The forward-backward asymmetry of $Z/\gamma^{*} \to \mu\mu$ pairs as a function of $\mu^+\mu^-$ mass, and the $\phi$ distribution of $Z$ bosons in the Collins-Soper frame are used to ascertain that the corrections remove the bias in the momentum measurements for positive versus negatively charged muons. By taking the sum and difference of the momentum scale corrections for positive and negative muons, we isolate additive corrections to $1/p^\mu_T$ that may originate from misalignments and multiplicative corrections that may originate from mis-modeling of the magnetic field $(\int \vec{B} \cdot d\vec{L})$. This method has recently been used in the CDF experiment at Fermilab and in the CMS experiment at the Large Hadron Collider at CERNComment: 6 pages, 3 figures, to be published in EPJC 201

Precision measurements of the top quark mass from the Tevatron in the pre-LHC era

The top quark is the heaviest of the six quarks of the Standard Model. Precise knowledge of its mass is important for imposing constraints on a number of physics processes, including interactions of the as yet unobserved Higgs boson. The Higgs boson is the only missing particle of the Standard Model, central to the electroweak symmetry breaking mechanism and generation of particle masses. In this Review, experimental measurements of the top quark mass accomplished at the Tevatron, a proton-antiproton collider located at the Fermi National Accelerator Laboratory, are described. Topologies of top quark events and methods used to separate signal events from background sources are discussed. Data analysis techniques used to extract information about the top mass value are reviewed. The combination of several most precise measurements performed with the two Tevatron particle detectors, CDF and \D0, yields a value of \Mt = 173.2 \pm 0.9 GeV/$c^2$.Comment: This version contains the most up-to-date top quark mass averag