New suppressed decays of Bs mesons at CDF

The observation of new suppressed Bs decays, Bs-> J/Psi K* (892)0 and Bs->J/Psi Ks, and the measurement of their branching ratios are presented. This measurement is based on an integrated luminosity of 5.9 fb-1 of CDF data collected by a dedicated di-muon trigger. A cut based optimization is carried out for the observation of Bs -> J/Psi K*, while a neural network is used for the Bs->J/Psi Ks. In addition to the observation of the new decay modes, the ratios of branching fractions to the reference B0 decays are measured.Comment: ICHEP 2010 conference proceedin

Inclusive jet production using the kt algorithm

Results on inclusive jet production using the k{sub T} algorithm in proton-antiproton collisions at {radical}s = 1.96 TeV are presented, based on 1 fb{sup -1} of CDF Run II data. The measurements are carried out for jets with p{sub T}{sup jet} > 54 GeV/c in five different jet rapidity regions up to |y{sub jet}| = 2.1. The measured cross sections are corrected to the hadron level and compared to next-to-leading order perturbative QCD predictions (NLO pQCD)

Inclusive jet production studies at the Tevatron using the CDF detector

Consultable des del TDXTítol obtingut de la portada digitalitzadaQCD es una teoría que gobierna la interacción fuerte entre quarks y gluones dentro de los hadrones, por ejemplo, protones y neutrones. Esta teoría tiene dos características: libertad asintótica y color confinamiento. La dependencia de la constante de acoplamiento con la escala es tal que esta decrece con la distancia entre partones. Esto permite realizar precisos cálculos teóricos a una gran escala de energía usando teoría de perturbaciones (pQCD). Además, la fuerza de la interacción incrementa con la distancia entre partones y gluones obligando que estos estén confinados en hadrones. En el acelerador Tevatron, protones y antiprotones colisionan a una alta energía. En estas colisiones se producen jets de hadrones colimados en la misma dirección de los quarks y gluones que han colisionado. La medida de la sección eficaz de producción de jets centrales constituye una prueba de las predicciones de pQCD en más de ocho órdenes de magnitud. Además la medida también es sensible a la distribución de los partones dentro del proton (PDFs). Medidas de la producción de jets a grandes rapidititis son importantes porque ayudan a restringir la incertidumbre en esas distribuciones de los partones en una región donde no se espera señal de nueva física. Esta tesis presenta la medida de producción de jets usando datos recogidos por el experimento CDF, uno de los detectores que estudia las colisiones en Tevatron. La medida esta hecha con un algoritmo muy preciso para buscar jets, relativamente nuevo en colisionadores hadrónicos. La medida esta comparada con predicciones de pQCD, donde los efectos de efectos no-perturbativos han sido incluidos. Los resultados demuestran que hay un excelente acuerdo entre la medida y la teoría, no mostrando señal de nueva física. Además, las incertidumbre es la medida son mas pequeñas que la teoría, cosa que indica que estas medidas pueden ser usadas para restringir las PDFs.QCD is the gauge theory that governs the strong interactions between quarks and gluons inside hadrons like, for example, protons and neutrons. It shows two well established characteristics, related to the non-abelian nature of the theory, that dominate its phenomenology: asymptotic freedom and color confinement. The dependence of the strong coupling with the hard scale is such that it decreases with decreasing the distance between partons. This allows performing precise theoretical calculations at large energy transfer using perturbative QCD (pQCD). In the other hand, the strength of the interaction increases with the distance between partons and thus colored quarks and gluons are forced to be confined inside colorless hadrons. At the Tevatron at Fermilab, protons and antiprotons collide at very high energy. In those collisions, collimated jets of hadrons are produced along the direction of struck quarks and gluons in the final state. The measurement of the inclusive jet production cross section provides a stringent test of pQCD predictions over almost nine orders of magnitude. In addition, the measurement is sensitive to the parton distribution in the proton (PDFs). Jet measurements at large rapidities are important because they constrain the gluon density in a region where no effect from new physics is expected. This PhD. Thesis presents a measurement of the inclusive jet production cross section using the new data collected by the CDF experiment in Run II, one of the detectors at Tevatron. The longitudinally invariant kT algorithm has been used in order to search for jets in the final state. The measurement is compared to pQCD NLO calculations where non-perturbative effects from the underlying event and the fragmentation of partons into jets of hadrons have been taken into account. The results show an excellent agreement between the measurements and the theory, without presenting signal for new physics. In addition the systematic uncertainties in the measurements are smaller than in the theory, indicating that these measurements can be used to constrain the PDFs

Search for large extra dimensions in the production of jets and missing transverse energy in p(p)over-bar collisions at root s=1.96 TeV

We present the results of a search for new physics in the jets plus missing transverse energy data sample collected from 368 pb(-1) of p (p) over bar collisions at root s = 1.96 TeV recorded by the Collider Detector at Fermilab. We compare the number of events observed in the data with a data-based estimate of the standard model backgrounds contributing to this signature. We observe no significant excess of events, and we interpret this null result in terms of lower limits on the fundamental Planck scale for a large extra dimensions scenario

Measurement of the W+W- Production Cross Section in ppbar Collisions at sqrt(s)=1.96 TeV using Dilepton Events

We present a measurement of the W+W- production cross section using 184/pb of ppbar collisions at a center-of-mass energy of 1.96 TeV collected with the Collider Detector at Fermilab. Using the dilepton decay channel W+W- -> l+l-vvbar, where the charged leptons can be either electrons or muons, we find 17 candidate events compared to an expected background of 5.0+2.2-0.8 events. The resulting W+W- production cross section measurement of sigma(ppbar -> W+W-) = 14.6 +5.8 -5.1 (stat) +1.8 -3.0 (syst) +-0.9 (lum) pb agrees well with the Standard Model expectation.Comment: 8 pages, 2 figures, 2 tables. To be submitted to Physical Review Letter

Measurement of the W+W- production cross section in p(p)over-bar collisions at root s=1.96 TeV using dilepton events

We present a measurement of the W+W- production cross section using 184 pb(-1) of p (p) over bar collisions at a center-of-mass energy of 1.96 TeV collected with the Collider Detector at Fermilab. Using the dilepton decay channel W+W-→ l(+)ν l(-)(ν) over bar, where the charged leptons can be either electrons or muons, we find 17 candidate events compared to an expected background of 5.0(-0.8)(+2.2) events. The resulting W+W- production cross-section measurement of σ(p (p) over bar → W+W-)=14.6(-5.1)(+5.8)(stat)(-3.0)(+1.8)(syst)± 0.9(lum) pb agrees well with the standard model expectation

Response of the ATLAS Tile Calorimeter to a radioactive source and muons

The ATLAS hadronic calorimeter calibration is based on a Cs source system and on Test Beam results. They are used not only to do the first inter-calibration of the different components of the calorimeter but also to obtain the initial EM scale for individual cells of TileCal. Since the year 2000, the first production-line modules of TileCal have been constructed and tested by exposing them to muon, pion, and electron beams at CERN SPS. They have also undergone calibration using the radiation from a Cs source. The main goal of the studies of the response of ATLAS Tile Calorimeter to a radioactive source and muons is to qualitativaly compare test beam and source data taken on TileCal production modules in order to understand better the calorimeter calibration procedure

QCD results at CDF

Recent QCD measurements from the CDF collaboration at the Tevatron are presented, together with future prospects as the luminosity increases. The measured inclusive jet cross section is compared to pQCD NLO predictions. Precise measurements on jet shapes and hadronic energy flows are compared to different phenomenological models that describe gluon emissions and the underlying event in hadron-hadron interactions

Inclusive jet production at the Tevatron

Preliminary results on inclusive jet production in proton-antiproton collisions at {radical}s = 1.96 TeV based on 1 fb{sup -1} of CDF Run II data are presented. Measurements are preformed using different jet algorithms in a wide range of jet transverse momentum and jet rapidity. The measured cross sections are compared to next-to-leading order perturbative QCD calculation

Inclusive jet cross-section measurement at CDF

The CDF Collaboration has measured the inclusive jet cross section using 1992-93 collider data at 1.8 TeV. The CDF measurement is in very good agreement with NLO QCD predictions for transverse energies (E{sub T}) below 200 GeV. However, it is systematically higher than NLO QCD predictions for E{sub T} above 200 GeV