Search results for "Invariant"
showing 10 items of 783 documents
A new observable to measure the top-quark mass at hadron colliders
2013
A new method to measure the top-quark mass in high energetic hadron collisions is presented. We use theoretical predictions calculated at next-to-leading order accuracy in quantum chromodynamics to study the ( normalized) differential distribution of the t (t) over bar + 1-jet cross section with respect to its invariant mass root s(t (t) over barj). The sensitivity of the method to the top-quark mass together with the impact of various theoretical and experimental uncertainties has been investigated and quantified. The new method allows for a complementary measurement of the top-quark mass parameter and has a high potential to become competitive in precision with respect to established appr…
Measurement of the charge asymmetry in top quark pair production in pp collisions at root s=7 TeV using the ATLAS detector
2012
A measurement of the top-antitop production charge asymmetry A[subscript C] is presented using data corresponding to an integrated luminosity of 1.04 fb[superscript −1] of pp collisions at s√=7 TeV collected by the ATLAS detector at the LHC. Events are selected with a single lepton (electron or muon), missing transverse momentum and at least four jets of which at least one jet is identified as coming from a b-quark. A kinematic fit is used to reconstruct the t[bar over t] event topology. After background subtraction, a Bayesian unfolding procedure is performed to correct for acceptance and detector effects. The measured value of A[subscript C] is A[subscript C]=−0.019±0.028 (stat.)±0.024 (s…
Equivalence relations among homology 3-spheres and the Johnson filtration
2021
The Torelli group of a surface consists of isotopy classes of homeomorphisms of this surface acting trivially at the homological level. The structure of the Torelli group can be approached by the study and the comparison of two filtrations of this group: its lower central series, and the "Johnson" filtration, given by the kernels of the natural actions on the successive nilpotent quotients of the fundamental group of the surface. It is now known that there are, via the notion of "Heegaard splittings", rich interactions between this 2-dimensional study and the study of some 3-manifolds topological invariants: we refer here precisely to the so-called "finite-type" invariants. In this PhD, we …
On C1 robust singular transitive sets for three-dimensional flows
1998
Abstract The main goal of this paper is to study robust invariant transitive sets containing singularities for C 1 flows on three-dimensional compact boundaryless manifolds: they are partially hyperbolic with volume expanding central direction. Moreover, they are either attractors or repellers. Robust here means that this property cannot be destroyed by small C 1 -perturbations of the flow.
Revisiting the axial form factor of the nucleon for low Q2 pion electroproduction
2003
Abstract An extensive programme of charged pion electroproduction off the proton has been performed at the three-spectrometer facility at the Mainz Microton MAMI. The reaction p ( e , e ′ π + ) n was measured at a constant invariant mass of W = 1125 MeV and four-momentum transfers of Q 2 = 0.058, 0.117, 0.195, and 0.273 (GeV/ c ) 2 . For each Q 2 value. measurements at different values of ϵ, the virtual photon polarization parameters, allow for a Rosenbluth separation of longitudinal and transverse cross sections. Preliminary results from new measurements in 2000 and 2002 seem to indicate that the transverse cross section at lower Q 2 values is considerably lower than expected from previous…
Invariants of transverse foliations
2012
Abstract We construct two invariants for a pair of transverse one-dimensional foliations on the plane. If the set of separatrices is Hausdorff in the space of leaves, the invariant is a distinguished graph. In case there are a finite number of separatrices the invariant is an indexed link.
A model for the γN → ππN reaction
1996
We have studied the γN → ππN reaction using a model wich includes N, Δ(1232), N*(1440) and N*(1520) intermediate baryonic states and the ρ-meson as a intermediate ππ resonance. The model reproduces fairly well experimental cross sections below Eγ=800 MeV and invariant-mass distributions even at higher energies. One of the interesting findings of study is what the γN → N*(1520) → Δπ process is very important and interferes strongly with the dominant Δ-Kroll-Ruderman term to produce the experimental peak of the kross section. Oset Baguena, Eulogio, Eulogio.Oset@ific.uv.es
Lingue, invarianti e altri strani oggetti
2011
The paper aims to analyze the concept of linguistic invariant introduced by several research programs in linguistics: from the typological linguistics to the theory of enunciative and predicative operations until some branches of the so-called Minimalist program. As we will shows, it is necessary to distinguish between «universals of language» and «linguistic invariant».
Sempre uguale sempre diverso. Riflessioni sulla nozione di invariante linguistico
2008
The paper aims to analyze the concept of linguistic invariant. It is a theoretical tool that plays a pivotal role in several research programs: from the typological linguistics to the theory of enunciative and predicative operations, until some branches of the so-called Minimalist program. As we will show, it is necessary to distinguish between «universal of language» and «linguistic invariant».
Automatic Relative Radiometric Normalization of Bi-Temporal Satellite Images Using a Coarse-to-Fine Pseudo-Invariant Features Selection and Fuzzy Int…
2022
Relative radiometric normalization (RRN) is important for pre-processing and analyzing multitemporal remote sensing (RS) images. Multitemporal RS images usually include different land use/land cover (LULC) types; therefore, considering an identical linear relationship during RRN modeling may result in potential errors in the RRN results. To resolve this issue, we proposed a new automatic RRN technique that efficiently selects the clustered pseudo-invariant features (PIFs) through a coarse-to-fine strategy and uses them in a fusion-based RRN modeling approach. In the coarse stage, an efficient difference index was first generated from the down-sampled reference and target images by combining…