654 research outputs found
Graduate Recital: David S. Golden, Jr., Trumpet; Beverly Pauli, Piano; April 29, 1975
Hayden AuditoriumTuesday EveningApril 29, 19758:30 p.m
Extended QCD(2) from dimensional projection of QCD(4)
We study an extended QCD model in (1+1) dimensions obtained from QCD in 4D by
compactifying two spatial dimensions and projecting onto the zero-mode
subspace. We work out this model in the large limit and using light cone
gauge but keeping the equal-time quantization. This system is found to induce a
dynamical mass for transverse gluons -- adjoint scalars in QCD(2), and to
undergo a chiral symmetry breaking with the full quark propagators yielding
non-tachyonic, dynamical quark masses, even in the chiral limit. We study
quark-antiquark bound states which can be classified in this model by their
properties under Lorentz transformations inherited from 4D. The scalar and
pseudoscalar sectors of the theory are examined and in the chiral limit a
massless ground state for pseudoscalars is revealed with a wave function
generalizing the so called 't Hooft pion solution.Comment: JHEP class, 16 pages, 3 figures. Change in the title, some
improvements in section 2, minors changes and comments added in introduction
and conclusions. References added. Version appearing in JHE
Gravitational and electroweak unification by replacing diffeomorphisms with larger group
The covariance group for general relativity, the diffeomorphisms, is replaced
by a group of coordinate transformations which contains the diffeomorphisms as
a proper subgroup. The larger group is defined by the assumption that all
observers will agree whether any given quantity is conserved. Alternatively,
and equivalently, it is defined by the assumption that all observers will agree
that the general relativistic wave equation describes the propagation of light.
Thus, the group replacement is analogous to the replacement of the Lorentz
group by the diffeomorphisms that led Einstein from special relativity to
general relativity, and is also consistent with the assumption of constant
light velocity that led him to special relativity. The enlarged covariance
group leads to a non-commutative geometry based not on a manifold, but on a
nonlocal space in which paths, rather than points, are the most primitive
invariant entities. This yields a theory which unifies the gravitational and
electroweak interactions. The theory contains no adjustable parameters, such as
those that are chosen arbitrarily in the standard model.Comment: 28 pages
Confined Quantum Time of Arrival for Vanishing Potential
We give full account of our recent report in [E.A. Galapon, R. Caballar, R.
Bahague {\it Phys. Rev. Let.} {\bf 93} 180406 (2004)] where it is shown that
formulating the free quantum time of arrival problem in a segment of the real
line suggests rephrasing the quantum time of arrival problem to finding a
complete set of states that evolve to unitarily arrive at a given point at a
definite time. For a spatially confined particle, here it is shown explicitly
that the problem admits a solution in the form of an eigenvalue problem of a
class of compact and self-adjoint time of arrival operators derived by a
quantization of the classical time of arrival. The eigenfunctions of these
operators are numerically demonstrated to unitarilly arrive at the origin at
their respective eigenvalues.Comment: accepted for publication in Phys. Rev.
Confined Quantum Time of Arrivals
We show that formulating the quantum time of arrival problem in a segment of
the real line suggests rephrasing the quantum time of arrival problem to
finding states that evolve to unitarily collapse at a given point at a definite
time. For the spatially confined particle, we show that the problem admits a
solution in the form of an eigenvalue problem of a compact and self-adjoint
time of arrival operator derived by a quantization of the classical time of
arrival, which is canonically conjugate with the Hamiltonian in closed subspace
of the Hilbert space.Comment: Figures are now include
Recommended from our members
PETROLEUM RESIDUA SOLUBILITY PARAMETER/POLARITY MAP: STABILITY STUDIES OF RESIDUA PYROLYSIS
A new molecular weight/polarity map based on the Scatchard-Hildebrand solubility equation has been developed for petroleum residua. A series of extractions are performed with solvents of increasing solubility parameter, and the fractions are analyzed by vapor pressure osmometry for number average molecular weight and by analytical-scale size exclusion chromatography for molecular weight spread. Work was performed for a heavy oil material subjected to three increasing severities of thermal treatment prior to and through the onset of coke formation. The results are diagnostic of the layers of solvations by resin-type molecules around a central asphaltene core. Two additional stability diagnostic methods were also used. These were the Heithaus titration ''P-index'' and Gaestel ''G'' index, which have been applied to paving asphalts for decades. The Heithaus titration involves the titration of three toluene solutions of a residuum at three concentrations with a poor solvent, such as isooctane, to the point of asphaltene flocculation. In the present work, the significance of the data are developed in terms of the Hildebrand solubility parameter. The Heithaus results are combined with data from the new molecular weight/polarity map. The solubility parameters for the toluene-soluble asphaltene components are measured, and the solubility parameters of the maltenes can be calculated. As thermal treatment progresses, the solubility parameters of asphaltene materials increase and the molecular weights decrease. A new coking index is proposed based on Heithaus titration data. Preliminary results suggest that an alternative, simpler coking index may be developed by measuring the weight percent of cyclohexane solubles in heptane asphaltenes. Coking onset appears to coincide with the depletion of these resin-type asphaltene solubilizing components of residua. The objective of the present study was to develop a mapping tool that will enhance understanding of the changes that occur in residua during upgrading and support the industry-sponsored work in which Western Research Institute is engaged. WRI performs proprietary industry-sponsored residua and heavy oil upgrading process development and optimization research. The new mapping tool can be used for evaluating heavy oils and residua in both upstream and downstream operations
Nonperturbative Renormalization in Light-Cone Quantization
Two approaches to nonperturbative renormalization are discussed for theories
quantized on the light cone. One is tailored specifically to a calculation of
the dressed-electron state in quantum electrodynamics, where an invariant-mass
cutoff is used as a regulator and a Tamm-Dancoff truncation is made to include
no more than two photons. The other approach is based on Pauli-Villars
regulators and is applied to Yukawa theory and a related soluble model. In both
cases discretized light-cone quantization is used to obtain a finite matrix
problem that can be solved nonperturbatively.Comment: 10 pages, LaTeX/RevTex, no figures, to appear in the proceedings of
Orbis Scientiae 1997: Twenty-Five Coral Gables Conferences and their Impact
on High Energy Physics and Cosmology, B.N. Kursunoglu, e
Desenvolvimento de um Processo para Anodização com Utilização de Cátodo de Carbono em Parafusos Biomédicos
A partir da intensificação do processo de Globalização Tecnológica e o advento da chamada Indústria 4.0 e seus processos supereficientes, inúmeras áreas da indústria de transformação buscam o aperfeiçoamento técnico como única garantia de oferecer aos clientes produtos de qualidade competitiva ao nÃvel global, além da obtenção de processos eficientes e de baixo custo, capazes de reduzir os custos finais e assim, apresentar preços competitivos, destacando-se nesse sentido a indústria médica e odontológica. O presente estudo parte da importância dos biomateriais para a indústria biomédica, especialmente o caso do titânio. Em parceria firmada com a empresa Protus Materiais para Medicina, foi idealizado um novo processo de anodização de alguns corpos de prova de titânio puro Grau 2, utilizando eletrólito de ácido sulfúrico para coloração dos corpos de prova. As cores obtidas podem ser utilizadas para fins de identificação de componentes fabricados com as liga de titânio, e esta tecnologia pode vir a ser implantadas em diversas empresas da área de biomateriais. Conclui-se, a respeito do novo processo, que foi possÃvel obter a coloração dos corpos de prova exatamente como esperado, caracterizando-se uma inovação de processo
On Quantum State Observability and Measurement
We consider the problem of determining the state of a quantum system given
one or more readings of the expectation value of an observable. The system is
assumed to be a finite dimensional quantum control system for which we can
influence the dynamics by generating all the unitary evolutions in a Lie group.
We investigate to what extent, by an appropriate sequence of evolutions and
measurements, we can obtain information on the initial state of the system. We
present a system theoretic viewpoint of this problem in that we study the {\it
observability} of the system. In this context, we characterize the equivalence
classes of indistinguishable states and propose algorithms for state
identification
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