On Statistical Aspects of Qjets

The process by which jet algorithms construct jets and subjets is inherently ambiguous and equally well motivated algorithms often return very different answers. The Qjets procedure was introduced by the authors to account for this ambiguity by considering many reconstructions of a jet at once, allowing one to assign a weight to each interpretation of the jet. Employing these weighted interpretations leads to an improvement in the statistical stability of many measurements. Here we explore in detail the statistical properties of these sets of weighted measurements and demonstrate how they can be used to improve the reach of jet-based studies.Comment: 29 pages, 6 figures. References added, minor modification of the text. This version to appear in JHE

Qjets: A Non-Deterministic Approach to Tree-Based Jet Substructure

Jet substructure is typically studied using clustering algorithms, such as kT, which arrange the jets' constituents into trees. Instead of considering a single tree per jet, we propose that multiple trees should be considered, weighted by an appropriate metric. Then each jet in each event produces a distribution for an observable, rather than a single value. Advantages of this approach include: 1) observables have significantly increased statistical stability; and, 2) new observables, such as the variance of the distribution, provide new handles for signal and background discrimination. For example, we find that employing a set of trees substantially reduces the observed fluctuations in the pruned mass distribution, enhancing the likelihood of new particle discovery for a given integrated luminosity. Furthermore, the resulting pruned mass distributions for (background) QCD jets are found to be substantially wider than that for (signal) jets with intrinsic mass scales, e.g. jets containing a W decay. A cut on this width yields a substantial enhancement in significance relative to a cut on the standard pruned jet mass alone. In particular the luminosity needed for a given significance requirement decreases by a factor of two relative to standard pruning.Comment: Minor changes to match journal versio

Irreducibility and reducibility for the energy representation of the group of mappings of a Riemannian manifold into a compact semisimple Lie group

AbstractThe irreducibility of the energy representation of the group of smooth mappings from a Riemannian manifold of dimension d ⩾ 3 into a compact semisimple Lie group is proven. The nonequivalence of the representations associated with different Riemann structures is also proven for d ⩾ 3. The case d = 2 is examined and irreducibility and nonequivalence results are also given. The reducibility in the case d = 1 is pointed out (in this case the commutant contains a representation equivalent with the energy representation)

Factoriality of representations of the group of paths on SU(n)

AbstractFactoriality in the cyclic component of the vacuum for the energy representation of SU(n)-valued paths groups is proved. The main tool is a lemma concerning generic pairs of Cartan subalgebras in the Lie algebra su(n) of SU(n) groups

Jet Trimming

Initial state radiation, multiple interactions, and event pileup can contaminate jets and degrade event reconstruction. Here we introduce a procedure, jet trimming, designed to mitigate these sources of contamination in jets initiated by light partons. This procedure is complimentary to existing methods developed for boosted heavy particles. We find that jet trimming can achieve significant improvements in event reconstruction, especially at high energy/luminosity hadron colliders like the LHC.Comment: 20 pages, 11 figures, 3 tables - Minor changes to text/figure

Feasibility study for a numerical aerodynamic simulation facility. Volume 1

A Numerical Aerodynamic Simulation Facility (NASF) was designed for the simulation of fluid flow around three-dimensional bodies, both in wind tunnel environments and in free space. The application of numerical simulation to this field of endeavor promised to yield economies in aerodynamic and aircraft body designs. A model for a NASF/FMP (Flow Model Processor) ensemble using a possible approach to meeting NASF goals is presented. The computer hardware and software are presented, along with the entire design and performance analysis and evaluation

Analysis of the Segmental Phonological System of Maleku Based on Previous Descriptions

This paper is an analysis of the segmental phonological system of Maleku (Guatuso) on the basis of previously published phonological and phonetic descriptions. It has a particular focus on the distinctive features that contrast the phonemes, since no other publication has addressed this topic in detail before. In the patrimonial consonantal system, a total equivalence is established between the values of the features [sonorant] and [voice] if the phoneme classified as a voiced palatal fricative is considered a “sonorant fricative”. On the other hand, in the innovative system, which incorporates four phonemes borrowed from Spanish, the contrastivity of the feature [voice] is activated due to the introduction of voiced stop phonemes that contrast with the unvoiced stops.En este artículo se analiza el sistema fonológico segmental del malecu (guatuso) a partir de descripciones fonológicas y fonéticas anteriormente publicadas. El análisis en cuestión tiene un enfoque particular en los rasgos distintivos que contrastan los fonemas, ya que ninguna obra anterior ha abordado este tema con detalle. En el sistema consonántico patrimonial se determina que existe una equivalencia total entre los valores de los rasgos [sonante] y [sonoro] si el fonema clasificado como fricativo palatal sonoro es considerado “fricativo sonante”. En cambio, en el sistema innovador, el cual incorpora cuatro fonemas tomados en préstamo del español, se activa la contrastividad del rasgo [sonoro] debido a la introducción de fonemas oclusivos sonoros que se oponen a los oclusivos sordos

Análisis del sistema fonológico segmental del malecu con base en descripciones anteriores

En este artículo se analiza el sistema fonológico segmental del malecu (guatuso) a partir de descripciones fonológicas y fonéticas anteriormente publicadas. El análisis en cuestión tiene un enfoque particular en los rasgos distintivos que contrastan los fonemas, ya que ninguna obra anterior ha abordado este tema con detalle. En el sistema consonántico patrimonial se determina que existe una equivalencia total entre los valores de los rasgos [sonante] y [sonoro] si el fonema clasificado como fricativo palatal sonoro es considerado “fricativo sonante”. En cambio, en el sistema innovador, el cual incorpora cuatro fonemas tomados en préstamo del español, se activa la contrastividad del rasgo [sonoro] debido a la introducción de fonemas oclusivos sonoros que se oponen a los oclusivos sordos

Quantum electrodynamics of relativistic bound states with cutoffs

We consider an Hamiltonian with ultraviolet and infrared cutoffs, describing the interaction of relativistic electrons and positrons in the Coulomb potential with photons in Coulomb gauge. The interaction includes both interaction of the current density with transversal photons and the Coulomb interaction of charge density with itself. We prove that the Hamiltonian is self-adjoint and has a ground state for sufficiently small coupling constants.Comment: To appear in "Journal of Hyperbolic Differential Equation