Search for Higgs bosons predicted in two-Higgs-doublet models via decays to tau lepton pairs in 1.96-TeV p anti-p collisions

We present the results of a search for Higgs bosons predicted in two-Higgs-doublet models, in the case where the Higgs bosons decay to tau lepton pairs, using 1.8 fb{sup -1} of integrated luminosity of p{bar p} collisions recorded by the CDF II experiment at the Fermilab Tevatron. Studying the mass distribution in events where one or both tau leptons decay leptonically, no evidence for a Higgs boson signal is observed. The result is used to infer exclusion limits in the two-dimensional space of tan {beta} versus m{sub A} (the ratio of the vaccum expectation values of the two Higgs doublets and the mass of the pseudoscalar boson, respectively)

The AM++ board for the silicon vertex tracker upgrade at CDF

The silicon vertex trigger (SVT) processor has been built at CDF for extremely fast (~10 musec) and high precision (roughly offline quality) pattern recognition. It is going to be upgraded to have at high luminosity the same crucial role it had in the data collection for the RUN II physics. A modern version of most of the SVT boards is obtained with a minimum of new hardware. A pulsar board, which was designed for and is now being used in the CDF level-2 upgrade, has been used for most the SVT functions that needed to be upgraded. The pulsar combines the power of dedicated hardware with the flexibility of general purpose CPUs. The new sequencer (AMS) that controls the associative memory (AM) operation for pattern recognition, uses a small fraction of a pulsar board. The same pulsar is powerful enough to also carry out the road warrior function (AMS-RW), to remove redundant track candidates prior to track fitting. We report about the AMS-RW design, tests and performance

Search for Standard Model Higgs Boson Production in Association with a W Boson using a Neural Network

We present a search for standard model Higgs boson production in association with a W boson in proton-antiproton collisions (p{bar p} {yields} W{sup {+-}}H {yields} {ell}{nu}b{bar b}) at a center of mass energy of 1.96 TeV. The search employs data collected with the CDF II detector that correspond to an integrated luminosity of approximately 1.9 fb{sup -1}. We select events consistent with a signature of a single charged lepton (e{sup {+-}}/{mu}{sup {+-}}), missing transverse energy, and two jets. Jets corresponding to bottom quarks are identified with a secondary vertex tagging method, a jet probability tagging method, and a neural network filter. We use kinematic information in an artificial neural network to improve discrimination between signal and background compared to previous analyses. The observed number of events and the neural network output distributions are consistent with the standard model background expectations, and we set 95% confidence level upper limits on the production cross section times branching fraction ranging from 1.2 to 1.1 pb or 7.5 to 102 times the standard model expectation for Higgs boson masses from 110 to 150 GeV/c{sup 2}, respectively

Measurement of the top quark mass using the template method in the lepton plus jets channel with in situ W ---> j j calibration at CDF-II

We report an updated measurement of the top quark mass in the lepton plus jets channel of t{bar t} events from p{bar p} collisions at {radical}s = 1.96 TeV. This measurement uses a dataset with integrated luminosity of 680 pb{sup -1}, containing 360 t{bar t} candidates separated into four subsamples. A top quark mass is reconstructed for each event by using energy and momentum constraints on the top quark pair decay products. We also employ the reconstructed mass of hadronic W boson decays W {yields} jj to constrain in situ the largest systematic uncertainty of the top quark mass measurement: the jet energy scale. Monte Carlo templates of the reconstructed top quark and W boson mass are produced as a function of the true top quark mass and the jet energy scale. The distribution of reconstructed top quark and W boson mass in the data are compared to the Monte Carlo templates using a likelihood fit to obtain: M{sub top} = 173.4 {+-} 2.8 GeV/c{sup 2}

Study of ordered hadron chains with the ATLAS detector

La lista completa de autores que integran el documento puede consultarse en el archivo

Study of the material of the ATLAS inner detector for Run 2 of the LHC

Instituto de Física La Plat