Navegação Ciências Exatas e da Terra por Título
Resultados 4270-4289 de 5964
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Quantization of gauge-invariant theories through the dirac-bracket formalism
(1981) [Artigo de periódico]A physical system possessing first-class constraints is quantized by using the Dirac-bracket formalism. The main features of this quantization procedure are analyzed. The model enables us to present a situation where ... -
Quantum critical behavior and thermodynamics of the repulsive one-dimensional Hubbard model in a magnetic field
(2020) [Artigo de periódico]Even though the Hubbard model is one of the most fundamental models of highly correlated electrons, analytical and numerical data describing its thermodynamics at nonzero magnetization are relatively scarce. We present a ... -
Quantum criticality of spin-1 bosons in a one-dimensional harmonic trap
(2012) [Artigo de periódico]We investigate universal thermodynamics and quantum criticality of spin-1 bosons with strongly repulsive density-density and antiferromagnetic spin-exchange interactions in a one-dimensional harmonic trap. From the equation ... -
Quantum critical point in the spin glass-Kondo transition in heavy-fermion systems
(2004) [Artigo de periódico]The Kondo–spin glass competition is studied in a theoretical model of a Kondo lattice with an intrasite Kondo-type exchange interaction treated within the mean-field approximation, an intersite quantum Ising exchange ... -
Quantum density anomaly in optically trapped ultracold gases
(2020) [Artigo de periódico]Water, the substance of life, is known for its myriad of anomalous properties, whose origins are still the subject of intense debates. In order to provide a different insight into this problem, we show how its density ... -
Quantum dynamics of chiral fermions in a model with anomalous breaking of gauge invariance
(1986) [Artigo de periódico]We study the quantum dynamics of chiral fermion fields minimally coupled to a gauge field. The model, originally proposed by Jackiw and Rajaraman, is known to exhibit the anomalous breaking of gauge invariance, which leads ... -
Quantum electrodynamics with zero bare ferminon mass
(1964) [Artigo de periódico] -
Quantum phase transitions in an interacting atom-molecule boson model
(2010) [Artigo de periódico]We study the quantum phase transitions of a model that describes the interconversion of interacting bosonic atoms and molecules. Using a classical analysis, we identify a threshold coupling line separating a molecular phase ... -
Quantum phase transitions in Bose–Einstein condensates from a Bethe ansatz perspective
(2012) [Artigo de periódico]We investigate two solvable models for Bose–Einstein condensates and extract physical information by studying the structure of the solutions of their Bethe ansatz equations. A careful observation of these solutions for the ... -
Quantum Physics teaching and the theory of Social representations : investigating the presence of quantum mysticism concepts among high school students in the south of Brazil
(2023) [Artigo de periódico]The present work deals with possibilities for contribution of the Theory of Social Representations (TSR) as a reference for group learning, with techniques and methodologies that are specific to it, to facilitate the ... -
Quantum spherical spin glass : supersymmetry and annealing
(2007) [Artigo de periódico]We show that the effective action of the quantum spherical spin glass is invariant under a generalized form of Becchi-Rouet-Stora-Tyutin supersymmetry. The Ward identities associated with this invariance indicate that the ... -
Quantum spin glass : a replica-symmetric theory with positive entropy
(1986) [Artigo de periódico]In the present paper we present a detailed analysis of quantum effects in the spin-glass transition as described by a quantum Heisenberg analogue of the Sherrington-Kirkpatrick model. The spin operators are represented in ... -
A quantum toy-model for inelastic scattering and catalysis based on Bäcklund transformations
(2022) [Artigo de periódico]This work presents a scalar self-consistent quantum model for molecular simulation. This model employs Bäcklund transformations to eliminate the wave function from Klein-Gordon and Schrödinger-type equations. The nonlinear ... -
Quarkonium photoproduction in pp and AA collisions at the LHC
(2016) [Artigo de periódico]In this contribution we report on the investigations of the exclusive production of quarkonium states in proton-proton and nucleus-nucleus reactions at the LHC using the theoretical framework of the light-cone dipole ... -
Quarkonium plus prompt-photon associated hadroproduction and nuclear shadowing
(2010) [Artigo de periódico]Quarkonium hadroproduction in association with a photon at high energies provides a probe of the dynamics of the strong interactions as it is dependent on the nuclear gluon distribution. Therefore, it could be used to ... -
Quasi-free scattering of polarized electrons by polarized nuclear protons
(1977) [Artigo de periódico]It Is shown that quasi-free electron scattering in a suitable geometry takes place on strongly polarized nuclear protons. A calculation for the single particle model of 160 predicts large asymmetries for the scattering of ... -
Quasilinear analysis of loss-cone driven weakly relativistic electron cyclotron maser instability
(1995) [Artigo de periódico]This paper presents a quasilinear analysis of the relativistic electron cyclotron maser instability. Two electron popUlations are assumed: a low-temperature background component and a more energetic loss-cone population. ... -
Quasilinear evolution of cyclotron maser instability
(1995) [Artigo de periódico]A quasilinear analysis of the relativistic electron cyclotron maser instability is presented. A background plasma is assumed to support the wave motion, while the instability is driven by a tenuous population of energetic ... -
Quasilinear evolution of the weakly relativistic electron cyclotron maser instability
(1997) [Artigo de periódico]This paper presents a quasilinear analysis of the relativistic electron cyclotron maser instability in which the self-consistent set of equations governing the evolution of the particle distribution function and the energy ... -
Quasinormal modes and stability of accelerating Reissner-Norsdtröm AdS black holes
(2022) [Artigo de periódico]We investigate the numerical stability of accelerating AdS black holes against linear scalar perturbations. In particular, we study the evolution of a probe non-minimally coupled scalar field on Schwarzschild and ...