Detection of visual patterns disturbed by noise: An exploratory study

Contains fulltext : 15400.pdf (publisher's version ) (Open Access)An introductory study of the perception of stochastically specified events is reported. The initial problem was to determine whether the perceiver can split visual input data of this kind into random and determined components. The inability of subjects to do so with the stimulus material used (a filmlike sequence of dot patterns), led to the more general question of how subjects code this kind of visual material. To meet the difficulty of defining the subjects' responses, two experiments were designed. In both, patterns were presented as a rapid sequence of dots on a screen. The patterns were more or less disturbed by “noise,” i.e. the dots did not appear exactly at their proper places. In the first experiment the response was a rating on a semantic scale, in the second an identification from among a set of alternative patterns. The results of these experiments give some insight in the coding systems adopted by the subjects. First, noise appears to be detrimental to pattern recognition, especially to patterns with little spread. Second, this shows connections with the factors obtained from analysis of the semantic ratings, e.g. easily disturbed patterns show a large drop in the semantic regularity factor, when only a little noise is added

The connotation of musical consonance

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Measurements of Wγ and Zγ production in pp collisions at √s = 7 TeV with the ATLAS detector at the LHC

The integrated and differential fiducial cross sections for the production of a W or Z boson in association with a high-energy photon are measured using pp collisions at √s = 7  TeV. The analyses use a data sample with an integrated luminosity of 4.6  fb−1 collected by the ATLAS detector during the 2011 LHC data-taking period. Events are selected using leptonic decays of the W and Z bosons [W(eν,μν) and Z(e+e−, μ+μ−, νν)] with the requirement of an associated isolated photon. The data are used to test the electroweak sector of the Standard Model and search for evidence for new phenomena. The measurements are used to probe the anomalous WWγ, ZZγ, and Zγγ triple-gauge-boson couplings and to search for the production of vector resonances decaying to Zγ and Wγ. No deviations from Standard Model predictions are observed and limits are placed on anomalous triple-gauge-boson couplings and on the production of new vector meson resonances

Measurement of angular correlations in Drell-Yan lepton pairs to probe Z/ γ* boson transverse momentum at √s= 7 TeV with the ATLAS detector

A measurement of angular correlations in Drell-Yan lepton pairs via the ϕη* observable is presented. This variable probes the same physics as the Z/γ* boson transverse momentum with a better experimental resolution. The Z/γ*→e+e and Z/γ*→μ+μ− decays produced in proton-proton collisions at a centre-of-mass energy of √s=7 TeV are used. The data were collected with the ATLAS detector at the LHC and correspond to an integrated luminosity of 4.6 fb−1. Normalised differential cross sections as a function of ϕη* are measured separately for electron and muon decay channels. These channels are then combined for improved accuracy. The cross section is also measured double differentially as a function of ϕη* for three independent bins of the Z boson rapidity. The results are compared to QCD calculations and to predictions from different Monte Carlo event generators. The data are reasonably well described, in all measured Z boson rapidity regions, by resummed QCD predictions combined with fixed-order perturbative QCD calculations or by some Monte Carlo event generators. The measurement precision is typically better by one order of magnitude than present theoretical uncertainties

Measurement of the cross-section for W boson production in association with b-jets in pp collisions at √s=7 TeV with the ATLAS detector

This paper reports a measurement of the W +b-jets (W +b+ X and W +bb+X) production cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC. These results are based on data corresponding to an integrated luminosity of 4.6 fb−1, collected with the ATLAS detector. Cross-sections are presented as a function of jet multiplicity and of the transverse momentum of the leading b-jet for both the muon and electron decay modes of the W boson. The W +b-jets cross-section, corrected for all known detector effects, is quoted in a limited kinematic range. Combining the muon and electron channels, the fiducial cross-section for W +b-jets is measured to be 7.1 ± 0.5 (stat) ± 1.4 (syst) pb, consistent with the next-to-leading order QCD prediction, corrected for non-perturbative and double-parton interactions (DPI) contributions, of 4.70 ± 0.09 (stat) +0.60−0.49 (scale) ±0.06 (PDF) ±0.16 (non-pert) +0.52−0.38 (DPI) pb

Search for the neutral Higgs bosons of the minimal supersymmetric standard model in pp collisions at √s = 7 TeV with the ATLAS detector

A search for neutral Higgs bosons of the Minimal Supersymmetric Standard Model (MSSM) is reported. The analysis is based on a sample of proton-proton collisions at a centre-of-mass energy of 7 TeV recorded with the ATLAS detector at the Large Hadron Collider. The data were recorded in 2011 and correspond to an integrated luminosity of 4.7 fb−1 to 4.8 fb−1. Higgs boson decays into oppositely-charged muon or τ lepton pairs are considered for final states requiring either the presence or absence of b-jets. No statistically significant excess over the expected background is observed and exclusion limits at the 95% confidence level are derived. The exclusion limits are for the production cross-section of a generic neutral Higgs boson, ϕ, as a function of the Higgs boson mass and for h/A/H production in the MSSM as a function of the parameters mA and tanβ in the mmaxh scenario for mA in the range of 90 GeV to 500 GeV

Search for direct third-generation squark pair production in final states with missing transverse momentum and two b-jets in √s = 8 TeV pp collisions with the ATLAS detector

The results of a search for pair production of supersymmetric partners of the Standard Model third-generation quarks are reported. This search uses 20.1 fb−1 of pp collisions at √s = 8 TeV collected by the ATLAS experiment at the Large Hadron Collider. The lightest bottom and top squarks (b~1 and t~1 respectively) are searched for in a final state with large missing transverse momentum and two jets identified as originating from b-quarks. No excess of events above the expected level of Standard Model background is found. The results are used to set upper limits on the visible cross section for processes beyond the Standard Model. Exclusion limits at the 95 % confidence level on the masses of the third-generation squarks are derived in phenomenological supersymmetric R-parity-conserving models in which either the bottom or the top squark is the lightest squark. The b~1 is assumed to decay via b~1 →b~0χ1 and the t~1 via t~1 →b~±χ1, with undetectable products of the subsequent decay of the ~±χ1 due to the small mass splitting between the ~±χ1 and the ~0χ1

Search for contact interactions and large extra dimensions in dilepton events from pp collisions at √s = 7 TeV with the ATLAS detector

A search for nonresonant new phenomena, originating from either contact interactions or large extra spatial dimensions, has been carried out using events with two isolated electrons or muons. These events, produced at the LHC in proton-proton collisions at √s=7  TeV, were recorded by the ATLAS detector. The data sample, collected throughout 2011, corresponds to an integrated luminosity of 4.9 and 5.0  fb−1 in the e+e− and μ+μ− channels, respectively. No significant deviations from the Standard Model expectation are observed. Using a Bayesian approach, 95% confidence level lower limits ranging from 9.0 to 13.9 TeV are placed on the energy scale of ℓℓqq contact interactions in the left-left isoscalar model. Lower limits ranging from 2.4 to 3.9 TeV are also set on the string scale in large extra dimension models. After combining these limits with results from a similar search in the diphoton channel, slightly more stringent limits are obtained