1,120 research outputs found
Fermion Production in the Background of Minkowski Space Classical Solutions in Spontaneously Broken Gauge Theory
We investigate fermion production in the background of Minkowski space
solutions to the equations of motion of gauge theory spontaneously
broken via the Higgs mechanism. First, we attempt to evaluate the topological
charge of the solutions. We find that for solutions is not well-defined
as an integral over all space-time. Solutions can profitably be characterized
by the (integer-valued) change in Higgs winding number . We show
that solutions which dissipate at early and late times and which have nonzero
must have at least the sphaleron energy. We show that if we couple
a quantized massive chiral fermion to a classical background given by a
solution, the number of fermions produced is , and is not related
to .Comment: Version to be published. Argument showing that the topological charge
of solutions is undefined has been strengthened and clarified. Conclusions
unchange
Robustness of adiabatic quantum computation
We study the fault tolerance of quantum computation by adiabatic evolution, a
quantum algorithm for solving various combinatorial search problems. We
describe an inherent robustness of adiabatic computation against two kinds of
errors, unitary control errors and decoherence, and we study this robustness
using numerical simulations of the algorithm.Comment: 11 pages, 5 figures, REVTe
Gauge Invariant Variables for Spontaneously Broken SU(2) Gauge Theory in the Spherical Ansatz
We describe classical solutions to the Minkowski space equations of motion of
SU(2) gauge theory coupled to a Higgs field in the spatial spherical ansatz. We
show how to reduce the equations to four equations for four gauge invariant
degrees of freedom which correspond to the massive gauge bosons and the Higgs
particle. The solutions typically dissipate at very early and late times. To
describe the solutions at early and late times, we linearize and decouple the
equations of motion, all the while working only with gauge invariant variables.
We express the change in Higgs winding of a solution in terms of gauge
invariant variables.Comment: latex, 19 pages, no figures (minor changes to text; reference added
Unforgeable Noise-Tolerant Quantum Tokens
The realization of devices which harness the laws of quantum mechanics
represents an exciting challenge at the interface of modern technology and
fundamental science. An exemplary paragon of the power of such quantum
primitives is the concept of "quantum money". A dishonest holder of a quantum
bank-note will invariably fail in any forging attempts; indeed, under
assumptions of ideal measurements and decoherence-free memories such security
is guaranteed by the no-cloning theorem. In any practical situation, however,
noise, decoherence and operational imperfections abound. Thus, the development
of secure "quantum money"-type primitives capable of tolerating realistic
infidelities is of both practical and fundamental importance. Here, we propose
a novel class of such protocols and demonstrate their tolerance to noise;
moreover, we prove their rigorous security by determining tight fidelity
thresholds. Our proposed protocols require only the ability to prepare, store
and measure single qubit quantum memories, making their experimental
realization accessible with current technologies.Comment: 18 pages, 5 figure
Towards Designing a Knowledge Sharing System for Higher Learning Institutions in the UAE Based on the Social Feature Framework
Numerous ICT instruments, such as communication tools, social media platforms, and collaborative software, bolster and facilitate knowledge sharing activities. Determining the vital success factors for knowledge sharing within its unique context is argued to be essential before implementing it. Therefore, it is imperative to define domain-specific critical success factors when envisioning the design of a knowledge sharing system. This research paper introduces the blueprint for an Academic Knowledge Sharing System (AKSS), rooted in an essential success framework tailored to knowledge sharing to deploy within an academic institution. In this regard, an extensive exploration of the relevant literature led to the formulation of the research hypothesis that guided the construction of a questionnaire targeting university students through the online platform Pollfish, utilizing a quantitative approach to investigate, while the data collected was analyzed using SPSS version 22. The study unveils critical factors, including encouragement, acknowledgment, a reward system, fostering a knowledge sharing culture, and leading by example, contributing to developing the knowledge sharing framework. Furthermore, the study illustrates how this framework seamlessly integrated into the design, implementation, and execution of the Academic Knowledge Sharing System (AKSS)
Spherical Shells of Classical Gauge Field and their Topological Charge as a Perturbative Expansion
We consider the classical equations of motion of gauge theory,
without a Higgs field, in Minkowski space. We work in the spherical ansatz and
develop a perturbative expansion in the coupling constant for solutions
which in the far past look like freely propagating spherical shells. The
topological charge of these solutions is typically non-integer. We then
show that can be expressed as a power series expansion in which can be
nonzero at finite order. We give an explicit analytic calculation of the order
contribution to for specific initial pulses. We discuss the relation
between our findings and anomalous fermion number violation, and speculate on
the physical implications of our results.Comment: 18 pages in REVTE
Modeling the strangeness content of hadronic matter
The strangeness content of hadronic matter is studied in a string-flip model
that reproduces various aspects of the QCD-inspired phenomenology, such as
quark clustering at low density and color deconfinement at high density, while
avoiding long range van der Waals forces. Hadronic matter is modeled in terms
of its quark constituents by taking into account its internal flavor (u,d,s)
and color (red, blue, green) degrees of freedom. Variational Monte-Carlo
simulations in three spatial dimensions are performed for the ground-state
energy of the system. The onset of the transition to strange matter is found to
be influenced by weak, yet not negligible, clustering correlations. The phase
diagram of the system displays an interesting structure containing both
continuous and discontinuous phase transitions. Strange matter is found to be
absolutely stable in the model.Comment: 14 pages, 1 table, 8 eps figures, revtex. Submitted to Phys. Rev. C,
Presented at INPC2001 Berkeley, Ca. july 29-Aug
Correlations around an interface
We compute one-loop correlation functions for the fluctuations of an
interface using a field theory model. We obtain them from Feynman diagrams
drawn with a propagator which is the inverse of the Hamiltonian of a
Poschl-Teller problem. We derive an expression for the propagator in terms of
elementary functions, show that it corresponds to the usual spectral sum, and
use it to calculate quantities such as the surface tension and interface
profile in two and three spatial dimensions. The three-dimensional quantities
are rederived in a simple, unified manner, whereas those in two dimensions
extend the existing literature, and are applicable to thin films. In addition,
we compute the one-loop self-energy, which may be extracted from experiment, or
from Monte Carlo simulations. Our results may be applied in various scenarios,
which include fluctuations around topological defects in cosmology,
supersymmetric domain walls, Z(N) bubbles in QCD, domain walls in magnetic
systems, interfaces separating Bose-Einstein condensates, and interfaces in
binary liquid mixtures.Comment: RevTeX, 13 pages, 6 figure
New excitations in bcc He - an inelastic neutron scattering study
We report neutron scattering measurements on bcc solid % He. We studied
the phonon branches and the recently discovered ''optic-like'' branch along the
main crystalline directions. In addition, we discovered another, dispersionless
"optic-like'' branch at an energy around 1 meV (~11K). The properties of
the two "optic-like" branches seem different. Since one expects only 3 acoustic
phonon branches in a monoatomic cubic crystal, these new branches must
represent different type of excitations. One possible interpretation involves
localized excitations unique to a quantum solid.Comment: 4 pages, 3 figures, accepted by PRB, Rapid Communication
Quantum mechanics gives stability to a Nash equilibrium
We consider a slightly modified version of the Rock-Scissors-Paper (RSP) game
from the point of view of evolutionary stability. In its classical version the
game has a mixed Nash equilibrium (NE) not stable against mutants. We find a
quantized version of the RSP game for which the classical mixed NE becomes
stable.Comment: Revised on referee's criticism, submitted to Physical Review
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