Global Search for New Physics with 2.0/fb at CDF

Data collected in Run II of the Fermilab Tevatron are searched for indications of new electroweak-scale physics. Rather than focusing on particular new physics scenarios, CDF data are analyzed for discrepancies with the standard model prediction. A model-independent approach (Vista) considers gross features of the data, and is sensitive to new large cross-section physics. Further sensitivity to new physics is provided by two additional algorithms: a Bump Hunter searches invariant mass distributions for "bumps" that could indicate resonant production of new particles; and the Sleuth procedure scans for data excesses at large summed transverse momentum. This combined global search for new physics in 2.0/fb of ppbar collisions at sqrt(s)=1.96 TeV reveals no indication of physics beyond the standard model.Comment: 8 pages, 7 figures. Final version which appeared in Physical Review D Rapid Communication

Search for Standard Model Higgs Boson Production in Association with a W Boson at CDF

35 pages, 10 figuresWe present a search for standard model Higgs boson production in association with a W boson in proton-antiproton collisions ($p\bar{p}\to W^\pm H \to \ell\nu b\bar{b}$) at a center of mass energy of 1.96 TeV. The search employs data collected with the CDF II detector which correspond to an integrated luminosity of approximately 1 fb-1. We select events consistent with a signature of a single lepton ($e^\pm/\mu^\pm$), missing transverse energy, and two jets. Jets corresponding to bottom quarks are identified with a secondary vertex tagging method and a neural network filter technique. The observed number of events and the dijet mass distributions are consistent with the standard model background expectations, and we set 95% confidence level upper limits on the production cross section times branching ratio ranging from 3.9 to 1.3 pb for Higgs boson masses from 110 to 150 GeV/c2, respectively

Search for Standard Model Higgs Boson Production in Association with a W Boson at CDF

35 pages, 10 figuresWe present a search for standard model Higgs boson production in association with a W boson in proton-antiproton collisions ($p\bar{p}\to W^\pm H \to \ell\nu b\bar{b}$) at a center of mass energy of 1.96 TeV. The search employs data collected with the CDF II detector which correspond to an integrated luminosity of approximately 1 fb-1. We select events consistent with a signature of a single lepton ($e^\pm/\mu^\pm$), missing transverse energy, and two jets. Jets corresponding to bottom quarks are identified with a secondary vertex tagging method and a neural network filter technique. The observed number of events and the dijet mass distributions are consistent with the standard model background expectations, and we set 95% confidence level upper limits on the production cross section times branching ratio ranging from 3.9 to 1.3 pb for Higgs boson masses from 110 to 150 GeV/c2, respectively

Search for Standard Model Higgs Boson Production in Association with a W Boson at CDF

35 pages, 10 figuresInternational audienceWe present a search for standard model Higgs boson production in association with a W boson in proton-antiproton collisions ($p\bar{p}\to W^\pm H \to \ell\nu b\bar{b}$) at a center of mass energy of 1.96 TeV. The search employs data collected with the CDF II detector which correspond to an integrated luminosity of approximately 1 fb-1. We select events consistent with a signature of a single lepton ($e^\pm/\mu^\pm$), missing transverse energy, and two jets. Jets corresponding to bottom quarks are identified with a secondary vertex tagging method and a neural network filter technique. The observed number of events and the dijet mass distributions are consistent with the standard model background expectations, and we set 95% confidence level upper limits on the production cross section times branching ratio ranging from 3.9 to 1.3 pb for Higgs boson masses from 110 to 150 GeV/c2, respectively

Top Quark Mass Measurement in the tt-bar All Hadronic Channel using a Matrix Element Technique in ppbar Collisions at sqrt s = 1.96 TeV

submitted to Phys. Rev. DWe present a measurement of the top quark mass in the all-hadronic channel (\tt $\to$ \bb$q_{1}\bar{q_{2}}q_{3}\bar{q_{4}}$) using 943 pb$^{-1}$ of \ppbar collisions at $\sqrt {s} = 1.96$ TeV collected at the CDF II detector at Fermilab (CDF). We apply the standard model production and decay matrix-element (ME) to \ttbar candidate events. We calculate per-event probability densities according to the ME calculation and construct template models of signal and background. The scale of the jet energy is calibrated using additional templates formed with the invariant mass of pairs of jets. These templates form an overall likelihood function that depends on the top quark mass and on the jet energy scale (JES). We estimate both by maximizing this function. Given 72 observed events, we measure a top quark mass of 171.1 $\pm$ 3.7 (stat.+JES) $\pm$ 2.1 (syst.) GeV/$c^{2}$. The combined uncertainty on the top quark mass is 4.3 GeV/$c^{2}$

Observation of exclusive charmonium production and gamma+gamma to mu+mu- in p+pbar collisions at sqrt{s} = 1.96 TeV

7 pages, 3 figures, 1 tableWe have observed the reactions p+pbar --> p+X+pbar, with X being a centrally produced J/psi, psi(2S) or chi_c0, and gamma+gamma --> mu+mu-, in proton- antiproton collisions at sqrt{s} = 1.96 TeV using the Run II Collider Detector at Fermilab. The event signature requires two oppositely charged muons, each with pseudorapidity |eta| mu+mu-. Events with a J/psi and an associated photon candidate are consistent with exclusive chi_c0 production through double pomeron exchange. The exclusive vector meson production is as expected for elastic photo- production, gamma+p --> J/psi(psi(2S)) + p, which is observed here for the first time in hadron-hadron collisions. The cross sections ds/dy(y=0) for p + pbar --> p + X + pbar with X = J/psi, psi(2S) orchi_c0 are 3.92+/-0.62 nb, 0.53+/-0.14 nb, and 75+/-14 nb respectively. The cross section for the continuum, with |eta(mu+/-)| < 0.6, M(mumu) in [3.0,4.0] GeV/c2, is [Integral ds/(dM.deta1.deta2)] = 2.7+/-0.5 pb, consistent with QED predictions. We put an upper limit on the cross section for odderon exchange in J/psi production: ds/dy(y=0) (J/psi_O/IP) < 2.3 nb at 95% C.L

Search for new particles decaying into dijets in proton-antiproton collisions at sqrt(s) = 1.96 TeV

10 pages, 4 figuresWe present a search for new particles whose decays produce two jets (dijets) using proton-antiproton collision data corresponding to an integrated luminosity of 1.13 fb-1 collected with the CDF II detector. The measured dijet mass spectrum is found to be consistent with next-to-leading-order perturbative QCD predictions, and no significant evidence of new particles is found. We set upper limits at the 95% confidence level on cross sections times the branching fraction for the production of new particles decaying into dijets with both jets having a rapidity magnitude |y| < 1. These limits are used to determine the mass exclusions for the excited quark, axigluon, flavor-universal coloron, E6 diquark, color-octet technirho, W', and Z'

Measurement of the kTk_{T} Distribution of Particles in Jets Produced in p\barp Collisions at s=1.96\sqrt{s}=1.96 TeV

Submitted to PRLWe present a measurement of the transverse momentum with respect to the jet axis ($k_{T}$) of particles in jets produced in $p\bar p$ collisions at $\sqrt{s}=1.96$ TeV. Results are obtained for charged particles within a cone of opening angle 0.5 radians around the jet axis in events with dijet invariant masses between 66 and 737 GeV/c$^{2}$. The experimental data are compared to theoretical predictions obtained for fragmentation partons within the framework of resummed perturbative QCD using the modified leading log and next-to-modified leading log approximations. The comparison shows that trends in data are successfully described by the theoretical predictions, indicating that the perturbative QCD stage of jet fragmentation is dominant in shaping basic jet characteristics

Search for High-Mass \boldmathe+e−e^+e^- Resonances in \boldmathppˉp\bar{p} Collisions at \boldmaths=\sqrt{s}=1.96 TeV

submitted to Phys. Rev. LettA search for high-mass resonances in the $e^+e^-$ final state is presented based on $\sqrt{s}=$1.96 TeV $p\bar{p}$ collision data from the CDF II detector at the Fermilab Tevatron from an integrated luminosity of 2.5 fb$^{-1}$. The largest excess over the standard model prediction is at an $e^+e^-$ invariant mass of 240 GeV/$c^2$. The probability of observing such an excess arising from fluctuations in the standard model anywhere in the mass range of 150--1,000 GeV/$c^2$ is 0.6% (equivalent to 2.5 $\sigma$). We set Bayesian upper limits on $\sigma(p\bar{p}\to X)\cdot\mathcal{B}(X\to e^+e^-)$ at the 95% credibility level, where $X$ is a spin 1 or spin 2 particle, and we exclude the standard model coupling $Z'$ and the Randall-Sundrum graviton for $k/\overline{M}_{Pl}=0.1$ with masses below 963 and 848 GeV/$c^2$, respectively

Measurement of the top quark mass at CDF using the "neutrino ϕ\phi weighting" template method on a lepton plus isolated track sample

Submitted to Phys. Rev. DWe present a measurement of the top quark mass with t-tbar dilepton events produced in p-pbar collisions at the Fermilab Tevatron ($\sqrt{s}$=1.96 TeV) and collected by the CDF II detector. A sample of 328 events with a charged electron or muon and an isolated track, corresponding to an integrated luminosity of 2.9 fb$^{-1}$, are selected as t-tbar candidates. To account for the unconstrained event kinematics, we scan over the phase space for the azimuthal angles ($\phi_{\nu_1},\phi_{\nu_2}$) of neutrinos and reconstruct the top quark mass by minimizing a $\chi^2$ function in the t-tbar dilepton hypothesis. We assign $\chi^2$-dependent weights to the solutions in order to build a preferred mass for each event. Preferred mass distributions (templates) are built from simulated t-tbar and background events, and parameterized in order to provide continuous probability density functions. A likelihood fit of the preferred mass distribution in data to a weighted sum of signal and background probability density functions gives a top quark mass of $165.5^{+{3.4}}_{-{3.3}}$(stat.)$\pm 3.1$(syst.) GeV/$c^2$