Search results for "Field Theory"
showing 10 items of 1188 documents
A Unified Theory of Psychophysical Laws in Auditory Intensity Perception.
2020
Psychophysical laws quantitatively relate perceptual magnitude to stimulus intensity. While most people have accepted Stevens's power function as the psychophysical law, few believe in Fechner's original idea using just-noticeable-differences (jnd) as a constant perceptual unit to educe psychophysical laws. Here I present a unified theory in hearing, starting with a general form of Zwislocki's loudness function (1965) to derive a general form of Brentano's law. I will arrive at a general form of the loudness-jnd relationship that unifies previous loudness-jnd theories. Specifically, the "slope," "proportional-jnd," and "equal-loudness, equal-jnd" theories, are three additive terms in the ne…
Observation of the rare decay K-S -> pi(0)e(+)e(-)
2003
A search for the decay Ks->pi0e+e- has been made by the NA48/1 experiment at the CERN SPS accelerator. Using data collected during 89 days in 2002 with a high-intensity Ks beam, 7 events were found with a background of 0.15 events. The branching fraction BR(Ks->pi0e+e-, m(ee) > 0.165 GeV/c^2) = (3.0^{+1.5}_{-1.2}(stat) +/-0.2 (syst)) x 10^{-9} has been measured. Using a vector matrix element and a form factor equal to one, the measurement gives BR(Ks->pi0e+e-) = (5.8^{+2.9}_{-2.4}) x 10^{-9}.
Teollisten perheyritysten kasvudynamiikan systeemiteoreettinen tarkastelu
2004
Exotic properties of neutrinos using effective Lagrangians and specific models
2013
289 páginas. Tesis Doctoral del Departamento de Física Teórica, de la Universidad de Valencia, y del Instituto de Física Corpuscular (IFIC).
The strong coupling constant: State of the art and the decade ahead
2022
This document provides a comprehensive summary of the state-of-the-art, challenges, and prospects in the experimental and theoretical study of the strong coupling $\alpha_s$. The current status of the seven methods presently used to determine $\alpha_s$ based on: (i) lattice QCD, (ii) hadronic $\tau$ decays, (iii) deep-inelastic scattering and parton distribution functions fits, (iv) electroweak boson decays, hadronic final-states in (v) e+e-, (vi) e-p, and (vii) p-p collisions, and (viii) quarkonia decays and masses, are reviewed. Novel $\alpha_s$ determinations are discussed, as well as the averaging method used to obtain the PDG world-average value at the reference Z boson mass scale, $\…
Open-source QCD analysis of nuclear parton distribution functions at NLO and NNLO
2019
We present new sets of nuclear parton distribution functions (nPDFs) at next-to-leading order (NLO) and next-to-next-to-leading order (NNLO). Our analyses are based on deeply inelastic scattering data with charged-lepton and neutrino beams on nuclear targets. In addition, a set of proton baseline PDFs is fitted within the same framework with the same theoretical assumptions. The results of this global QCD analysis are compared to existing nPDF sets and to the fitted cross sections. Also, the uncertainties resulting from the limited constraining power of the included experimental data are presented. The published work is based on an open-source tool, xFitter, which has been modified to be ap…
Highly occupied gauge theories in 2 + 1 dimensions : a self-similar attractor
2019
Motivated by the boost-invariant Glasma state in the initial stages in heavy-ion collisions, we perform classical-statistical simulations of SU(2) gauge theory in 2+1 dimensional space-time both with and without a scalar field in the adjoint representation. We show that irrespective of the details of the initial condition, the far-from-equilibrium evolution of these highly occupied systems approaches a unique universal attractor at high momenta that is the same for the gauge and scalar sectors. We extract the scaling exponents and the form of the distribution function close to this non-thermal fixed point. We find that the dynamics are governed by an energy cascade to higher momenta with sc…
Hard Two-Photon Contribution to Elastic Lepton-Proton Scattering Determined by the OLYMPUS Experiment
2017
The OLYMPUS collaboration reports on a precision measurement of the positron-proton to electron-proton elastic cross section ratio, $R_{2\gamma}$, a direct measure of the contribution of hard two-photon exchange to the elastic cross section. In the OLYMPUS measurement, 2.01~GeV electron and positron beams were directed through a hydrogen gas target internal to the DORIS storage ring at DESY. A toroidal magnetic spectrometer instrumented with drift chambers and time-of-flight scintillators detected elastically scattered leptons in coincidence with recoiling protons over a scattering angle range of $\approx 20\degree$ to $80\degree$. The relative luminosity between the two beam species was mo…
Four-dimensional representation of scattering amplitudes and physical observables through the application of the Loop-Tree Duality theorem
2019
Las últimas dos décadas han sido testigo de un tremendo progreso en la física teórica de alta precisión. Muchos avances han sido hechos, en particular, en la evaluación de diagramas multi-loop, pero el principal desafío yace en el tratamiento de las divergencias IR a través de eficientes esquemas de substracción. Con la complejidad del procedimiento incrementándose exponencialmente con el número de escalas, se ha hecho necesario tratar la cuestión desde un ángulo diferente, invocando así al desarrollo de nuevas técnicas. La Dualidad Lazo-Árbol (LTD, por sus siglas en inglés) provee de un nuevo marco para el cómputo de amplitudes con loops. A través de la modificación de la prescripción está…
Quantum aspects originated by Gravitation: from cosmology to astrophysics
2018
El estudio de campos cuánticos que se propagan en espacio-tiempos clásicos, curvos y dinámicos, ofrece una primera manera de evaluar las consecuencias de la teoría cuántica cuando los fenómenos gravitatorios no son despreciables. Esta es una cuestión importante que debe ser abordada cuando un campo gravitatorio intenso juega un papel principal en la dinámica de un sistema físico, tal como ocurre durante el universo temprano (inflación cósmica) o en la formación de agujeros negros astrofísicos. Una de las características más sorprendentes de esta materia es quizás el hecho de que el cálculo de observables físicos, incluso para campos sin interacción, frecuentemente involucra operadores cuadr…