1,140 research outputs found
Imitation Learning for Vision-based Lane Keeping Assistance
This paper aims to investigate direct imitation learning from human drivers
for the task of lane keeping assistance in highway and country roads using
grayscale images from a single front view camera. The employed method utilizes
convolutional neural networks (CNN) to act as a policy that is driving a
vehicle. The policy is successfully learned via imitation learning using
real-world data collected from human drivers and is evaluated in closed-loop
simulated environments, demonstrating good driving behaviour and a robustness
for domain changes. Evaluation is based on two proposed performance metrics
measuring how well the vehicle is positioned in a lane and the smoothness of
the driven trajectory.Comment: International Conference on Intelligent Transportation Systems (ITSC
Measurements of two-particle correlations in collisions at 91 GeV with ALEPH archived data
Measurements of two-particle angular correlations of charged particles
emitted in hadronic decays are presented. The archived
annihilation data at a center-of-mass energy of 91 GeV were collected with the
ALEPH detector at LEP between 1992 and 1995. The correlation functions are
measured over a broad range of pseudorapidity and full azimuth as a function of
charged particle multiplicity. No significant long-range correlation is
observed in either the lab coordinate analysis or the thrust coordinate
analysis, where the latter is sensitive to a medium expanding transverse to the
color string between the outgoing pair from boson decays. The
associated yield distributions in both analyses are in better agreement with
the prediction from the PYTHIA v6.1 event generator than from HERWIG v7.1.5.
They provide new insights to showering and hadronization modeling. These
results serve as an important reference to the observed long-range correlation
in proton-proton, proton-nucleus, and nucleus-nucleus collisions.Comment: Replaced with the published version. Added the journal reference and
the DO
Long-range near-side correlation in Collisions at 183-209 GeV with ALEPH Archived Data
The first measurement of two-particle angular correlations for charged
particles produced in annihilation up to GeV with
LEP-II data is presented. Hadronic data, archived at center-of-mass
energies ranging from 183 to 209 GeV, were collected using the ALEPH detector
at LEP. The angular correlation functions have been measured across a wide
range of pseudorapidities and the full azimuth in bins of charged particle
multiplicity. Results for data at high energies, which allow for
higher event multiplicities reaching approximately 50 than LEP-I at Z pole
energy, are presented for the first time. A long-range near-side excess in the
correlation function has been identified in the analysis when calculating
particle kinematic variables with respect to the thrust axis. Moreover, the
two-particle correlation functions were decomposed using a Fourier series, and
the resulting Fourier coefficients were compared with event generator
outputs. In events with high multiplicity featuring more than 50 particles, the
extracted magnitude from the data are compared to those from the Monte
Carlo reference.Comment: Updated Figure 3 with ALICE publication To be submitted to PR
Search for Pair-Produced Resonances Decaying to Quark Pairs in Proton-Proton Collisions at √s = 13 TeV
A general search for the pair production of resonances, each decaying to two quarks, is reported. The search is conducted separately for heavier resonances (masses above 400 GeV), where each of the four final-state quarks generates a hadronic jet resulting in a four-jet signature, and for lighter resonances (masses between 80 and 400 GeV), where the pair of quarks from each resonance is collimated and reconstructed as a single jet resulting in a two-jet signature. In addition, a b-tagged selection is applied to target resonances with a bottom quark in the final state. The analysis uses data collected with the CMS detector at the CERN LHC, corresponding to an integrated luminosity of 35.9 fb⁻¹, from proton-proton collisions at a center-of-mass energy of 13 TeV. The mass spectra are analyzed for the presence of new resonances, and are found to be consistent with standard model expectations. The results are interpreted in the framework of R-parity-violating supersymmetry assuming the pair production of scalar top quarks decaying via the hadronic coupling λ′′312 or λ′′323 and upper limits on the cross section as a function of the top squark mass are set. These results probe a wider range of masses than previously explored at the LHC, and extend the top squark mass limits in the ˜t→qq′ scenario
Search for electroweak production of charginos and neutralinos in multilepton final states in proton-proton collisions at √s = 13 TeV
Results are presented from a search for the direct electroweak production of charginos and neutralinos in signatures with either two or more leptons (electrons or muons) of the same electric charge, or with three or more leptons, which can include up to two hadronically decaying tau leptons. The results are based on a sample of proton-proton collision data collected at s√=13 TeV, recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 35.9 fb⁻¹. The observed event yields are consistent with the expectations based on the standard model. The results are interpreted in simplified models of supersymmetry describing various scenarios for the production and decay of charginos and neutralinos. Depending on the model parameters chosen, mass values between 180 GeV and 1150 GeV are excluded at 95% CL. These results significantly extend the parameter space probed for these particles in searches at the LHC. In addition, results are presented in a form suitable for alternative theoretical interpretations
Search for Standard Model Production of Four Top Quarks with Same-Sign and Multilepton Final States in Proton–proton Collisions at √s = 13 TeV
A search for standard model production of four top quarks (tt¯tt¯) is reported using events containing at least three leptons (e,μ) or a same-sign lepton pair. The events are produced in proton–proton collisions at a center-of-mass energy of 13TeV at the LHC, and the data sample, recorded in 2016, corresponds to an integrated luminosity of 35.9fb[superscript −1]. Jet multiplicity and flavor are used to enhance signal sensitivity, and dedicated control regions are used to constrain the dominant backgrounds. The observed and expected signal significances are, respectively, 1.6 and 1.0 standard deviations, and the tt¯tt¯ cross section is measured to be 16.9[superscript +13.8][subscript −11.4] fb, in agreement with next-to-leading-order standard model predictions. These results are also used to constrain the Yukawa coupling between the top quark and the Higgs boson to be less than 2.1 times its expected standard model value at 95% confidence level
Measurement of the transverse momentum spectrum of the Higgs boson produced in pp collisions at √s=8 TeV using H → WW decays
The cross section for Higgs boson production in pp collisions is studied using the H → W[superscript +]W[superscript −] decay mode, followed by leptonic decays of the W bosons to an oppositely charged electron-muon pair in the final state. The measurements are performed using data collected by the CMS experiment at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.4 fb[superscript −1]. The Higgs boson transverse momentum (p[subscript T]) is reconstructed using the lepton pair p[subscript T] and missing p[subscript T]. The differential cross section times branching fraction is measured as a function of the Higgs boson pTin a fiducial phase space defined to match the experimental acceptance in terms of the lepton kinematics and event topology. The production cross section times branching fraction in the fiducial phase space is measured to be 39 ± 8 (stat) ± 9 (syst) fb. The measurements are found to agree, within experimental uncertainties, with theoretical calculations based on the standard model. Keywords: Hadron-Hadron scattering (experiments), Higgs physicsNational Science Foundation (U.S.)United States. Department of Energ
Search for Low Mass Vector Resonances Decaying to Quark-Antiquark Pairs in Proton-Proton Collisions at √s = 13 TeV
A search is reported for a narrow vector resonance decaying to quark-antiquark pairs in proton-proton collisions at √s = 13 TeV, collected with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 2.7 fb⁻¹. The vector resonance is produced at large transverse momenta, with its decay products merged into a single jet. The resulting signature is a peak over background in the distribution of the invariant mass of the jet. The results are interpreted in the framework of a leptophobic vector resonance and no evidence is found for such particles in the mass range of 100-300 GeV. Upper limits at 95% confidence level on the production cross section are presented in a region of mass-coupling phase space previously unexplored at the LHC. The region below 140 GeV has not been explored by any previous experiments
Search for supersymmetry in events with at least one photon, missing transverse momentum, and large transverse event activity in proton-proton collisions at √s = 13 TeV
A search for physics beyond the standard model in final states with at least one photon, large transverse momentum imbalance, and large total transverse event activity is presented. Such topologies can be produced in gauge-mediated supersymmetry models in which pair-produced gluinos or squarks decay to photons and gravitinos via short-lived neutralinos. The data sample corresponds to an integrated luminosity of 35.9 fb[superscript −1] of proton-proton collisions at s√=13 TeV recorded by the CMS experiment at the LHC in 2016. No significant excess of events above the expected standard model background is observed. The data are interpreted in simplified models of gluino and squark pair production, in which gluinos or squarks decay via neutralinos to photons. Gluino masses of up to 1.50-2.00 TeV and squark masses up to 1.30-1.65 TeV are excluded at 95% confidence level, depending on the neutralino mass and branching fraction. Keywords: Hadron-Hadron scattering (experiments); Supersymmetry; Photon productio
Search for a new scalar resonance decaying to a pair of Z bosons in proton-proton collisions at √s=13 TeV
A search for a new scalar resonance decaying to a pair of Z bosons is performed in the mass range from 130 GeV to 3 TeV, and for various width scenarios. The analysis is based on proton-proton collisions recorded by the CMS experiment at the LHC in 2016, corresponding to an integrated luminosity of 35.9 fb⁻¹ at a center-of-mass energy of 13 TeV. The Z boson pair decays are reconstructed using the 4ℓ, 2ℓ2q, and 2ℓ2ν final states, where ℓ = e or μ. Both gluon fusion and electroweak production of the scalar resonance are considered, with a free parameter describing their relative cross sections. A dedicated categorization of events, based on the kinematic properties of associated jets, and matrix element techniques are employed for an optimal signal and background separation. A description of the interference between signal and background amplitudes for a resonance of an arbitrary width is included. No significant excess of events with respect to the standard model expectation is observed and limits are set on the product of the cross section for a new scalar boson and the branching fraction for its decay to ZZ for a large range of masses and widths. Keywords: Hadron-Hadron scattering (experiments); Higgs physic
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