Search for Gravitational Waves from Primordial Black Hole Binary Coalescences in the Galactic Halo

We use data from the second science run of the LIGO gravitational-wave detectors to search for the gravitational waves from primordial black hole (PBH) binary coalescence with component masses in the range 0.2--$1.0 M_\odot$. The analysis requires a signal to be found in the data from both LIGO observatories, according to a set of coincidence criteria. No inspiral signals were found. Assuming a spherical halo with core radius 5 kpc extending to 50 kpc containing non-spinning black holes with masses in the range 0.2--$1.0 M_\odot$, we place an observational upper limit on the rate of PBH coalescence of 63 per year per Milky Way halo (MWH) with 90% confidence.Comment: 7 pages, 4 figures, to be submitted to Phys. Rev.

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 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 inverse fb. We select events consistent with a signature of a single charged lepton, 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^2, respectively.We present a search for standard model Higgs boson production in association with a W boson in proton-antiproton collisions (pp̅ →W±H→ℓνbb̅ ) 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-1. We select events consistent with a signature of a single charged lepton (e±/μ±), 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/c2, respectively.Peer reviewe

Measurement of b hadron lifetimes in exclusive decays containing a J/psi in p-pbar collisions at sqrt(s)=1.96TeV

We report on a measurement of $b$-hadron lifetimes in the fully reconstructed decay modes B^+ -->J/Psi K+, B^0 --> J/Psi K*, B^0 --> J/Psi Ks, and Lambda_b --> J/Psi Lambda using data corresponding to an integrated luminosity of 4.3 ${\rm fb}^{-1}$, collected by the CDF II detector at the Fermilab Tevatron. The measured lifetimes are $\tau$B^+ = $1.639 \pm 0.009 ({\rm stat}) \pm 0.009 {\rm (syst) ~ ps}$, $\tau$B^0 = $1.507 \pm 0.010 ({\rm stat}) \pm 0.008 {\rm (syst) ~ ps}$ and $\tau$Lambda_b = $1.537 \pm 0.045 ({\rm stat}) \pm 0.014 {\rm (syst) ~ ps}$. The lifetime ratios are $\tau$B^+/$\tau$B^0 = $1.088 \pm 0.009 ({\rm stat})\pm 0.004 ({\rm syst})$ and $\tau$Lambda_b/$\tau$B^0 = $1.020 \pm 0.030 ({\rm stat})\pm 0.008 ({\rm syst})$. These are the most precise determinations of these quantities from a single experiment.Comment: revised version. accepted for PRL publicatio

Measurement of ZZ production in leptonic final states at {\surd}s of 1.96 TeV at CDF

In this paper we present a precise measurement of the total ZZ production cross section in pp collisions at {\surd}s= 1.96 TeV, using data collected with the CDF II detector corresponding to an integrated luminosity of approximately 6 fb-1. The result is obtained by combining separate measurements in the four-charged (lll'l'), and two-charged-lepton and two-neutral-lepton (llvv) decay modes of the Z. The combined measured cross section for pp {\to} ZZ is 1.64^(+0.44)_(-0.38) pb. This is the most precise measurement of the ZZ production cross section in 1.96 TeV pp collisions to date.Comment: submitted to Phys. Rev. Let

Measurement of b Hadron Lifetimes in Exclusive Decays Containing a J/Psi in p(p)over-bar Collisions at root s=1.96 TeV

We report on a measurement of b-hadron lifetimes in the fully reconstructed decay modes B+-> J/psi K+, B-0 -> J/psi K*(892)(0), B-0 -> J/psi K-s(0), and Lambda(0)(b)-> J/psi Lambda(0) using data corresponding to an integrated luminosity of 4.3 fb(-1), collected by the CDF II detector at the Fermilab Tevatron. The measured lifetimes are tau(B+)=[1.639 +/- 0.009(stat)+/- 0.009(syst)]ps, tau(B-0)=[1.507 +/- 0.010(stat)+/- 0.008(syst)]ps, and tau(Lambda(0)(b))=[1.537 +/- 0.045(stat)+/- 0.014(syst)]ps. The lifetime ratios are tau(B+)/tau(B-0)=[1.088 +/- 0.009(stat)+/- 0.004(syst)] and tau(Lambda(0)(b))/tau(B-0)=[1.020 +/- 0.030(stat)+/- 0.008(syst)]. These are the most precise determinations of these quantities from a single experiment

Search for High Mass Resonances Decaying to Muon Pairs in root s=1.96 TeV p(p)over-bar Collisions

We present a search for a new narrow, spin-1, high mass resonance decaying to mu(+)mu(-) + X, using a matrix-element-based likelihood and a simultaneous measurement of the resonance mass and production rate. In data with 4.6 fb(-1) of integrated luminosity collected by the CDF detector in p (p) over bar collisions at root s = 1960 GeV, the most likely signal cross section is consistent with zero at 16% confidence level. We therefore do not observe evidence for a high mass resonance and place limits on models predicting spin-1 resonances, including M > 1071 GeV/c(2) at 95% confidence level for a Z' boson with the same couplings to fermions as the Z boson

Insights into the High-energy γ-ray Emission of Markarian 501 from Extensive Multifrequency Observations in the Fermi Era

We report on the γ-ray activity of the blazar Mrk501 during the first 480 days of Fermi operation. We find that the average Large Area Telescope (LAT) -ray spectrum of Mrk501 can be well described by a single power-law function with a photon index of 1.78 0.03. While we observe relatively mild flux variations with the Fermi-LAT (within less than a factor of two), we detect remarkable spectral variability where the hardest observed spectral index within the LAT energy range is 1.52 0.14, and the softest one is 2.51 0.20. These unexpected spectral changes do not correlate with the measured flux variations above 0.3GeV. In this paper, we also present the first results from the 4.5 month long multifrequency campaign (2009 March 15August 1) on Mrk501, which included the Very Long Baseline Array (VLBA), Swift, RXTE, MAGIC, and VERITAS, the F-GAMMA, GASP-WEBT, and other collaborations and instruments which provided excellent temporal and energy coverage of the source throughout the entire campaign. The extensive radio to TeV data set from this campaign provides us with the most detailed spectral energy distribution yet collected for this source during its relatively low activity. The average spectral energy distribution of Mrk501 is well described by the standard one-zone synchrotron self-Compton (SSC) model. In the framework of this model, we find that the dominant emission region is characterized by a size r0.1pc (comparable within a factor of few to the size of the partially resolved VLBA core at 15-43 GHz), and that the total jet power (C1044ergs1) constitutes only a small fraction (<103) of the Eddington luminosity. The energy distribution of the freshly accelerated radiating electrons required to fit the time-averaged data has a broken power-law form in the energy range 0.3 GeV-10 TeV, with spectral indices 2.2 and 2.7 below and above the break energy of 20GeV. We argue that such a form is consistent with a scenario in which the bulk of the energy dissipation within the dominant emission zone of Mrk501 is due to relativistic, proton-mediated shocks. We find that the ultrarelativistic electrons and mildly relativistic protons within the blazar zone, if comparable in number, are in approximate energy equipartition, with their energy dominating the jet magnetic field energy by about two orders of magnitude

Upper limits on a stochastic background of gravitational waves

The Laser Interferometer Gravitational-Wave Observatory has performed a third science run with much improved sensitivities of all three interferometers. We present an analysis of approximately 200 hours of data acquired during this run, used to search for a stochastic background of gravitational radiation. We place upper bounds on the energy density stored as gravitational radiation for three different spectral power laws. For the flat spectrum, our limit of omega0 &lt;8.4 x 10(-4) in the 69-156 Hz band is approximately 10(5) times lower than the previous result in this frequency range