Search results for "3100"
showing 10 items of 83 documents
Translationally invariant treatment of pair correlations in nuclei: I. Spin and isospin dependent correlations
1996
We study the extension of our translationally invariant treatment of few-body nuclear systems to heavier nuclei. At the same time we also introduce state-dependent correlation operators. Our techniques are tailored to those nuclei that can be dealt with in $LS$ coupling, which includes all nuclei up to the shell closure at $A=40$. We study mainly $p$-shell nuclei in this paper. A detailed comparison with other microscopic many-body approaches is made, using a variety of schematic nuclear interactions. It is shown that our methodology produces very good energies, and presumably also wave functions, for medium mass nuclei.
The translationally-invariant coupled cluster method in coordinate space
2000
We study a formulation of the translationally-invariant coupled cluster method in coordinate space. Previous calculations in configuration space showed poor convergence, a problem that the new formulation is expected to remedy. This question is investigated for a system of bosons interacting through the Wigner part of the Afnan-Tang S3 interaction, where previous results exist.
Translationally invariant treatment of pair correlations in nuclei - II. Tensor correlations
1998
We study the extension of our translationally invariant treatment of few-body nuclear systems to include tensor forces and correlations. It is shown that a direct application of our method is not as successful for realistic V6 interactions as our previous results for V4 potentials suggested. We investigate the cause in detail for the case of $^4$He, and show that a combination of our method with that of Jastrow-correlated wave functions seems to be a lot more powerful, thereby suggesting that for mildly to strongly repulsive forces such a hybrid procedure may be an appropriate description.
Search for higgs bosons decaying to tau pairs in pp̄ collisions with the D0 detector
2008
Made available in DSpace on 2022-04-28T20:43:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-08-14 Science and Technology Facilities Council We present a search for the production of neutral Higgs bosons decaying into τ+τ- final states in pp̄ collisions at a center-of-mass energy of 1.96 TeV. The data, corresponding to an integrated luminosity of approximately 1fb-1, were collected by the D0 experiment at the Fermilab Tevatron Collider. Limits on the production cross section times branching ratio are set. The results are interpreted in the minimal supersymmetric standard model yielding limits that are the most stringent to date at hadron colliders. © 2008 The American Physical Soc…
Consistent Treatment of Axions in the Weak Chiral Lagrangian.
2021
We present a consistent implementation of weak decays involving an axion or axion-like particle in the context of an effective chiral Lagrangian. We argue that previous treatments of such processes have used an incorrect representation of the flavor-changing quark currents in the chiral theory. As an application, we derive model-independent results for the decays $K^-\to\pi^- a$ and $\pi^-\to e^-\bar\nu_e a$ at leading order in the chiral expansion and for arbitrary axion couplings and mass. In particular, we find that the $K^-\to\pi^- a$ branching ratio is almost 40 times larger than previously estimated.
Role of information backflow in the emergence of quantum Darwinism
2019
Quantum Darwinism attempts to explain the emergence of objective reality of the state of a quantum system in terms of redundant information about the system acquired by independent non interacting fragments of the environment. The consideration of interacting environmental elements gives rise to a rich phenomenology, including the occurrence of non-Markovian features, whose effects on objectification {\it a' la} quantum Darwinism needs to be fully understood. We study a model of local interaction between a simple quantum system and a multi-mode environment that allows for a clear investigation of the interplay between information trapping and propagation in the environment and the emergence…
Continuous-Variable Sampling from Photon-Added or Photon-Subtracted Squeezed States
2017
We introduce a new family of quantum circuits in Continuous Variables and we show that, relying on the widely accepted conjecture that the polynomial hierarchy of complexity classes does not collapse, their output probability distribution cannot be efficiently simulated by a classical computer. These circuits are composed of input photon-subtracted (or photon-added) squeezed states, passive linear optics evolution, and eight-port homodyne detection. We address the proof of hardness for the exact probability distribution of these quantum circuits by exploiting mappings onto different architectures of sub-universal quantum computers. We obtain both a worst-case and an average-case hardness re…
El análisis crítico del discurso y el Banquete de Platón: una aproximación del ACD y la filología clásica
2019
La tesis doctoral El análisis crítico del discurso y el Banquete de Platón: una aproximación del ACD y la filología clásica se inscribe en el programa de doctorado de Estudios de Género y Políticas de Igualdad. Se centra en el análisis del discurso con el objetivo de explorar las diferentes aportaciones teóricas y metodológicas del Análisis Crítico del Discurso (ACD) y en su aplicación al análisis de textos griegos clásicos, en concreto al diálogo filosófico de Platón. Esto ha supuesto seleccionar un modelo analítico estructural marco que permita su aplicación no solo a discursos actuales, sino también a discursos localizados en el contexto histórico y cultural de la Antigüedad clásica, ini…
Competition between memory-keeping and memory-erasing decoherence channels
2014
We study the competing effects of simultaneous Markovian and non-Markovian decoherence mechanisms acting on a single spin. We show the existence of a threshold in the relative strength of such mechanisms above which the spin dynamics becomes fully Markovian, as revealed by the use of several non-Markovianity measures. We identify a measure-dependent nested structure of such thresholds, hinting at a causality relationship among the various non-Markovianity witnesses used in our analysis. Our considerations are then used to argue the unavoidably non-Markovian evolution of a single-electron quantum dot exposed to both intrinsic and Markovian technical noise, the latter of arbitrary strength.
Characterization of the shape-staggering effect in mercury nuclei
2018
In rare cases, the removal of a single proton (Z) or neutron (N) from an atomic nucleus leads to a dramatic shape change. These instances are crucial for understanding the components of the nuclear interactions that drive deformation. The mercury isotopes (Z = 80) are a striking example1,2: their close neighbours, the lead isotopes (Z = 82), are spherical and steadily shrink with decreasing N. The even-mass (A = N + Z) mercury isotopes follow this trend. The odd-mass mercury isotopes 181,183,185Hg, however, exhibit noticeably larger charge radii. Due to the experimental difficulties of probing extremely neutron-deficient systems, and the computational complexity of modelling such heavy nucl…