No Arabic abstract
In Run II of the CDF experiment, traditional dilepton triggers are enriched by lepton (electrons or muons) plus track, di-tau and tau plus missing transverse energy triggers at Level-3 dedicated to physical processes including tau leptons. We describe these triggers, along with their physics motivations, implementation and cross-sections and report on their initial performance.
The study of processes containing tau leptons in the final state will play an important role at Tevatron Run II. Such final states will be relevant both for electroweak studies and measurements as well as in searches for physics beyond the Standard Model. The present paper discuss the physics opportunities and challenges related to the implementation of new set of triggers able to select events containing tau candidates in the final state. We illustrate, in particular, the physics capabilities for a variety of new physics scenarios such as supersymmetry (SUSY), SUSY with R-parity violation, with Bilinear parity violation or models with the violation of lepton flavor. Finally, we present the first Run II results obtained using some of the described tau triggers.
Many theoretical models, like the Standard Model or SUSY at large tan(beta), predict Higgs bosons or new particles which decay more abundantly to final states including tau leptons than to other leptons. At the energy scale of the LHC, the identification of tau leptons, in particular in the hadronic decay mode, will be a challenging task due to an overwhelming QCD background which gives rise to jets of particles that can be hard to distinguish from hadronic tau decays. Equipped with excellent tracking and calorimetry, the ATLAS experiment has developed tau identification tools capable of working at the trigger level. This contribution presents tau trigger algorithms which exploit the main features of hadronic tau decays and describes the current tau trigger commissioning activities.
The article describes the identification of hadronically decaying tau leptons in ppbar collisions at 1.96 TeV collected by the DZero detector at the Fermilab Tevatron. After a brief description of the motivations and the challenges of considering tau leptons in high energy hadronic collisions, details of the tau reconstruction and identification will be discussed. The challenges associated for tau energy measurements in an hadronic environment will be presented including approaches to deal with such measurements.
For the first time in a hadron collider, a novel trigger processor, the Silicon Vertex Trigger (SVT), allows to select the long-lived heavy flavor particles by cutting on the track impact parameter with a precision similar to that of the offline reconstruction. Triggering on displaced tracks has enriched the B-physics program by enhancing the B yields of the lepton-based triggers and opened up full hadronic triggering at CDF. After a first commissioning period, the SVT is fully operational, performing very closely to its design capabilities. System performance and first physics results based on SVT selected data samples are presented.
We present measurements of the masses and widths of four bottom baryon resonances, Sigma_b(*)+-, reconstructed in the Lambda_b pi+- hadron decay modes. The isospin mass splittings for the Sigma_b and Sigma_b* multiplets are extracted as well. The analysis is based on a data sample corresponding to an integrated luminosity of 6 fb^-1 .