2 The CDF Experiment at Fermilab Contents - Harvard University ...

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76 Section 2: CDF Physics Analysis 2.4.4 Missing Energy Trigger (Prof. Huth & Ms. Spiropulu) The 6E T trigger drives a number of analyses and the need for a carefully designed 6E T trigger for the Run II luminosity environment is evident. A few of the physics processes that can be studied with a data sample triggered by large energy imbalance are the following: Vector boson production and leptonic decays. Although there is a dedicated 6E T plus lepton trigger for the study of the W boson, W QCD associate production remains a crucial background for a number of New Phenomena searches and the 6E T plus jets trigger provides a good sample to study this as well as the W to process. For Z production and decay, the 6E T sample provides a dataset to measure directly the Z to cross section. Furthermore again, Z boson QCD associated production is a background to many New Phenomena searches. Top quark production and decay to W and b quark. The 6E T alternate dataset to measure the top cross section. trigger provides an Associate Higgs W and Higgs Z production. The 6E T combined with a b quark tagging or a tau lepton tagging trigger can provide a highly ecient triggering scheme for the discovery of the Higgs boson. New Phenomena searches. Just to mention a few, the 6E T trigger can be used to search for { supersymmetric partners: Supersymmetry, or minimal Supergravity inspired models usually contain the Lightest Supersymmetric Particle(LSP) in the nal state of the decays of the superparticles. The LSP escapes the detector and appears as energy imbalance. Examples are squark and gluino searches, scalar top and scalar bottom searches. { Gravitinos:In Gauge Mediated Supersymmetry Breaking scenarios that incorporate gravity the Lightest Supersymmetric Particle is the gravitino { the 3/2 spin partner of the graviton. The gravitino goes undetected and produced huge energy imbalance. In recent Gauge Mediated scenarios with very light gluino being the LSP, 6E T plus jets isafavored signature.
Section 2: Run II Triggers 77 { Leptoquarks where the leptoquark decays in a quark and a neutrino { CHArged Massive Particles (CHAMPS): These are long-lived massive particles that if they are penetrating enough can go undetected and cause energy imbalance. { Gravitons In Kaluza-Klein-type string theories of extra dimensions (where the extra dimension is physical but has compactied in the sense that for example the universe in this dimension is small compared to the smallest distances probed by experiments) the graviton can be produced in high energy hadron collisions and escape to the extra spatial dimension thus creating an energy imbalance in the usual 3 spatial dimension space. The study for the design of the 6E T trigger for Run II is using data from Run Ib. We calculate the rates for an inclusive 6E T trigger as well as a 6E T plus jets multilevel trigger. At the lower level (L1) the trigger requires 6E T > 25 GeV. At Level 2 (L2) the 6E T requirement remains the same and two jets of energy 10 GeV are required (we call it \L2 MET" trigger). At Level 3 (L3) the 6E T requirement is raised to 35 GeV. Compared to the RunI 6E T trigger, the rates are about the same although the luminosity is going to be signicantly higher at Run II. This is because although we lower the L2 6E T threshold from the previous run (30 GeV) the Main Ring that was responsible for more than one third of 6E T triggers at RunI does not longer exist. In the case of very high luminosity environment the 6E T threshold would need to be raised. The total trigger rate budget allows for an inclusive L26E T trigger of 45 GeV which would catch monojet events, photons and other potentially exotic events. For the L2 MET trigger we present the signal eciency for the following processes: SUSY, 300 GeV gluinos The upper left plot of Fig. 38 shows the L2 6E T trigger eciency for squark gluino production as a function of the 6E T trigger threshold and for the case of inclusive 6E T (solid triangles), of two jets of 6 GeV requirement (open squares), and two jets of 10 GeV requirement (open circles). The L2 MET trigger for this SUSY point is more than 90% ecient. top quark production. The upper right plot of Fig. 38 shows the L2 6E T Trigger eciency as a function of the 6E T trigger threshold. The L2 MET trigger for top (which is decaying inclusively) is about 60% ecient. W/Z Higgs associate production with the subsequent decay channels and Higgs mass as denoted in the bottom plots of Fig. 38. The L2 MET trigger is between 55% and 65% ecient depending on the process and the decay channels.
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1 2 The CDF Experiment at Fermilab
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