661 research outputs found

    Evaluating goal threat in football using player and ball locations

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    Goal scoring in football is relatively low but vitally important, hence research has considered how goals are created and scored with measures such as expected goals prevalent. The dynamical systems theoretical perspective, considers a collective system, such as football, as existing in two states, stable (no substantive advantage for either team) or unstable (advantage present). Hence, goal scoring events occur when the system has become unstable, with a “perturbation” the event causing the system state change. Here, a “goal threat” value was calculated every second (scaled from 0 to 100) using the XY coordinates of players and the ball, weighted in relation to proximity to the goal (a potential proxy for the degree of system instability). Video recordings and synchronised Amisco 2D representations of goals (n=64) scored in Swansea City AFC English Premier League 2012/2013 matches (n=20) were analysed using Dartfish v10 Pro software. Each goal was analysed from when the play was judged to be stable (no obvious goal scoring opportunity), or the start of possession, until the goal had been scored. Goals were not always preceded by high goal threat values (maximum goal threat values ranged from 13.4 to 99.0). The authors independently subjectively determined that perturbations occurred up to 7 seconds from when the goal threat value increased by at least 40%. Thus, perturbations were not directly related to goal scoring opportunities. This novel method provides a useful, quantifiable, and simple measure of goal threat that may also aid audience engagement and measure defensive effectiveness

    Three Millisecond Pulsars in FERMI LAT Unassociated Bright Sources

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    We searched for radio pulsars in 25 of the non-variable, unassociated sources in the Fermi LAT Bright Source List with the Green Bank Telescope at 820 MHz. We report the discovery of three radio and gamma-ray millisecond pulsars (MSPs) from a high Galactic latitude subset of these sources. All of the pulsars are in binary systems, which would have made them virtually impossible to detect in blind gamma-ray pulsation searches. They seem to be relatively normal, nearby (<=2 kpc) millisecond pulsars. These observations, in combination with the Fermi detection of gamma-rays from other known radio MSPs, imply that most, if not all, radio MSPs are efficient gamma-ray producers. The gamma-ray spectra of the pulsars are power-law in nature with exponential cutoffs at a few GeV, as has been found with most other pulsars. The MSPs have all been detected as X-ray point sources. Their soft X-ray luminosities of ~10^{30-31} erg/s are typical of the rare radio MSPs seen in X-rays.Comment: Accepted for publication in ApJ Letter

    A Search for Charmless BVVB\to VV Decays

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    We have studied two-body charmless decays of the BB meson into the final states ρ0ρ0\rho^0 \rho^0, K0ρ0K^{*0} \rho^0, K0K0K^{*0} K^{*0}, K0K0ˉK^{*0} \bar{K^{*0}}, K+ρ0K^{*+} \rho^0, K+K0ˉK^{*+} \bar{K^{*0}}, and K+KK^{*+} K^{*-} using only decay modes with charged daughter particles. Using 9.7 million BBˉB \bar{B} pairs collected with the CLEO detector, we place 90% confidence level upper limits on the branching fractions, (0.467.0)×105(0.46-7.0)\times 10^{-5}, depending on final state and polarization.Comment: 8 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

    Correlated /\c-/\cbar production in e+e- annihilations at sqrt{s}~10.5 GeV

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    Using 13.6/fb of continuum two-jet e+e- -> ccbar events collected with the CLEO detector, we have searched for baryon number correlations at the primary quark level. We have measured the likelihood for a /\c+ charmed baryon to be produced in the hemisphere opposite a /\c- relative to the likelihood for a /\c+ charmed baryon to be produced opposite an anticharmed meson Dbar; in all cases, the reconstructed hadrons must have momentum greater than 2.3 GeV/c. We find that, given a /\c- (reconstructed in five different decay modes), a /\c+ is observed in the opposite hemisphere (0.72+/-0.11)% of the time (not corrected for efficiency). By contrast, given a Dbar in one hemisphere, a /\c+ is observed in the opposite hemisphere only (0.21+/-0.02)% of the time. Normalized to the total number of either /\c- or Dbar ``tags'', it is therefore 3.52+/-0.45+/-0.42 times more likely to find a /\c+ opposite a /\c- than a Dbar meson. This enhancement is not observed in the JETSET 7.3 e+e- -> ccbar Monte Carlo simulation.Comment: 19 pages, Latex, one figure separat

    First Observation of barB0 to D*0 pi+pi+pi-pi- Decays

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    We report on the observation of B0bar -> D*0 pi+ pi+ pi- pi- decays. The branching ratio is (0.30 +/- 0.07 +/- 0.06)%. Interest in this particular mode was sparked by Ligeti, Luke and Wise who propose it as a way to check the validity of factorization tests in B0bar -> D*+ pi+ pi- pi- pi0 decays.Comment: 11 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, Version to appear in Phys. Rev.

    Hadronic Structure in the Decay τππ0ντ\tau^{-}\to \pi^{-}\pi^{0}\nu_{\tau}

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    We report on a study of the invariant mass spectrum of the hadronic system in the decay tau- -> pi- pi0 nu_tau. This study was performed with data obtained with the CLEO II detector operating at the CESR e+ e- collider. We present fits to phenomenological models in which resonance parameters associated with the rho(770) and rho(1450) mesons are determined. The pi- pi0 spectral function inferred from the invariant mass spectrum is compared with data on e+ e- -> pi+ pi- as a test of the Conserved Vector Current theorem. We also discuss the implications of our data with regard to estimates of the hadronic contribution to the muon anomalous magnetic moment.Comment: 39 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

    Eight gamma-ray pulsars discovered in blind frequency searches of Fermi LAT data

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    We report the discovery of eight gamma-ray pulsars in blind frequency searches using the LAT, onboard the Fermi Gamma-ray Space Telescope. Five of the eight pulsars are young (tau_c10^36 erg/s), and located within the Galactic plane (|b|<3 deg). The remaining three are older, less energetic, and located off the plane. Five pulsars are associated with sources included in the LAT bright gamma-ray source list, but only one, PSR J1413-6205, is clearly associated with an EGRET source. PSR J1023-5746 has the smallest characteristic age (tau_c=4.6 kyr) and is the most energetic (Edot=1.1E37 erg/s) of all gamma-ray pulsars discovered so far in blind searches. PSRs J1957+5033 and J2055+25 have the largest characteristic ages (tau_c~1 Myr) and are the least energetic (Edot~5E33 erg/s) of the newly-discovered pulsars. We present the timing models, light curves, and detailed spectral parameters of the new pulsars. We used recent XMM observations to identify the counterpart of PSR J2055+25 as XMMU J205549.4+253959. In addition, publicly available archival Chandra X-ray data allowed us to identify the likely counterpart of PSR J1023-5746 as a faint, highly absorbed source, CXOU J102302.8-574606. The large X-ray absorption indicates that this could be among the most distant gamma-ray pulsars detected so far. PSR J1023-5746 is positionally coincident with the TeV source HESS J1023-575, located near the young stellar cluster Westerlund 2, while PSR J1954+2836 is coincident with a 4.3 sigma excess reported by Milagro at a median energy of 35 TeV. Deep radio follow-up observations of the eight pulsars resulted in no detections of pulsations and upper limits comparable to the faintest known radio pulsars, indicating that these can be included among the growing population of radio-quiet pulsars in our Galaxy being uncovered by the LAT, and currently numbering more than 20.Comment: Submitted to Ap

    Measurement of Charge Asymmetries in Charmless Hadronic in B Meson Decays

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    We search for CP-violating asymmetries (Acp) in the B meson decays to K+- pi-+, K+- pi0, Ks pi+-, K+- eta', and omega pi+-. Using 9.66 million Upsilon(4S) decays collected with the CLEO detector, the statistical precision on Acp is in the range of \pm 0.12 to \pm 0.25 depending on decay mode. While CP-violating asymmetries of up to \pm 0.5 are possible within the Standard Model, the measured asymmetries are consistent with zero in all five decay modes studied.Comment: 10 pages, 3 figure

    First Observation of the Σc+\Sigma_{c}^{*+} Baryon and a New Measurement of the Σc+\Sigma_{c}^{+} Mass

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    Using data recorded with the CLEO II and CLEO II.V detector configurations at the Cornell Electron Storage Rings, we report the first observation and mass measurement of the Σc+\Sigma_c^{*+} charmed baryon, and an updated measurement of the mass of the Σc+\Sigma_c^+ baryon. We find M(Σc+)M(Λc+)M(\Sigma_c^{*+})-M(\Lambda_c^+)= 231.0 +- 1.1 +- 2.0 MeV, and M(Σc+)M(Λc+)M(\Sigma_c^{+})-M(\Lambda_c^+)= 166.4 +- 0.2 +- 0.3 MeV, where the errors are statistical and systematic respectively.Comment: 8 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN
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