Search results for "DF"
showing 10 items of 1699 documents
Improved Induction Tree Training for Automatic Lexical Categorization
2009
This paper studies a tuned version of an induction tree which is used for automatic detection of lexical word category. The database used to train the tree has several fields to describe Spanish words morpho-syntactically. All the processing is performed using only the information of the word and its actual sentence. It will be shown here that this kind of induction is good enough to perform the linguistic categorization.
The complexity of graph languages generated by hyperedge replacement
1990
Although in many ways, hyperedge replacement graph grammars (HRGs) are, among all graph generating mechanisms, what context-free Chomsky grammars are in the realm of string rewriting, their parsing problem is known to be, in general, NP-complete. In this paper, the main difficulty in HRG parsing is analysed and some conditions on either grammar or input graphs are developed under which parsing can be done in polynomial time. For some of the cases, the parsing problem is shown to be log-space reducible to context-free string parsing.
Combination of Tevatron searches for the standard model Higgs boson in the W+W- decay mode.
2010
11 páginas, 4 figuras, 1 tabla.-- CDF Collaboration: et al.
Nuclear structure functions at a future electron-ion collider
2017
The quantitative knowledge of heavy nuclei's partonic structure is currently limited to rather large values of momentum fraction $x$---robust experimental constraints below $x\ensuremath{\sim}{10}^{\ensuremath{-}2}$ at low resolution scale ${Q}^{2}$ are particularly scarce. This is in sharp contrast to the free proton's structure which has been probed in Deep Inelastic Scattering (DIS) measurements down to $x\ensuremath{\sim}{10}^{\ensuremath{-}5}$ at perturbative resolution scales. The construction of an electron-ion collider (EIC) with a possibility to operate with a wide variety of nuclei, will allow one to explore the low-$x$ region in much greater detail. In the present paper we simula…
Search for a Higgs Boson Decaying to Two W Bosons at CDF
2008
We present a search for a Higgs boson decaying to two W bosons in p (p) over bar collisions at root s = 1.96 TeV center-of-mass energy. The data sample corresponds to an integrated luminosity of 3.0 fb(-1) collected with the CDF II detector. We find no evidence for production of a Higgs boson with mass between 110 and 200 GeV/c(2), and determine upper limits on the production cross section. For the mass of 160 GeV/c(2), where the analysis is most sensitive, the observed (expected) limit is 0.7 pb (0.9 pb) at 95% Bayesian credibility level which is 1.7 (2.2) times the standard model cross section.
First Observation of Vector Boson Pairs in a Hadronic Final State at the Tevatron Collider
2009
We present the first observation in hadronic collisions of the electroweak production of vector boson pairs (VV, V=W, Z) where one boson decays to a dijet final state. The data correspond to 3.5 fb(-1) of integrated luminosity of pp collisions at s=1.96 TeV collected by the CDF II detector at the Fermilab Tevatron. We observe 1516 +/- 239(stat)+/- 144(syst) diboson candidate events and measure a cross section sigma(pp -> VV+X) of 18.0 +/- 2.8(stat)+/- 2.4(syst)+/- 1.1(lumi) pb, in agreement with the expectations of the standard model.
Combination of CDF and D0 W-Boson mass measurements
2013
We summarize and combine direct measurements of the mass of the W boson in √s=1.96 TeV proton-antiproton collision data collected by CDF and D0 experiments at the Fermilab Tevatron Collider. Earlier measurements from CDF and D0 are combined with the two latest, more precise measurements: a CDF measurement in the electron and muon channels using data corresponding to 2.2 fb-1 of integrated luminosity, and a D0 measurement in the electron channel using data corresponding to 4.3 fb-1 of integrated luminosity. The resulting Tevatron average for the mass of the W boson is M W=80387±16 MeV. Including measurements obtained in electron-positron collisions at LEP yields the most precise value of M W…
Probing the small- x nuclear gluon distributions with isolated photons at forward rapidities in p+Pb collisions at the LHC
2014
Inclusive direct photon production in p+Pb collisions at the LHC is studied within the NLO perturbative QCD. Our aim is to quantify the dominant $x$ regions probed at different rapidities and to identify the best conditions for testing the nuclear gluon parton distribution functions (nPDFs) at small $x$. A comparison to the inclusive pion production reveals that from these two processes the photons carry more sensitivity to the small-$x$ partons and that this sensitivity can be further increased by imposing an isolation cut for the photon events. The details of the isolation criteria, however, seem to make only a small difference to the studied $x$ sensitivity and have practically no effect…
Measurement of azimuthal hadron asymmetries in semi-inclusive deep inelastic scattering off unpolarised nucleons
2014
Spin-averaged asymmetries in the azimuthal distributions of positive and negative hadrons produced in deep inelastic scattering were measured using the CERN SPS muon beam at $160$ GeV/c and a $^6$LiD target. The amplitudes of the three azimuthal modulations $\cos\phi_h$, $\cos2\phi_h$ and $\sin\phi_h$ were obtained binning the data separately in each of the relevant kinematic variables $x$, $z$ or $p_T^{\,h}$ and binning in a three-dimensional grid of these three variables. The amplitudes of the $\cos \phi_h$ and $\cos 2\phi_h$ modulations show strong kinematic dependencies both for positive and negative hadrons.
Great tit (Parus major) breeding in fire-prone oak woods: differential effects of post-fire conditions on reproductive stages
2011
Wildfires negatively affect the overall reproductive success of several woodland avian species, but there is scarce information about which stages of the nesting cycle are specifically affected. We conducted a 3-year study to identify the effects of fire on the reproductive parameters of the great tit (Parus major) and the survival of its nests at different stages of the nesting cycle. We recorded the occupancy rate, clutch and brood size, hatching, fledging and nesting success in nest boxes placed on study plots with different post-fire age. By examining the post-fire succession, we analysed the survival of eggs and nestlings under predation risks. As the forest matured after a wildfire, …