Results 1 - 10 of 2796
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[en] Using data from FOCUS (E831) experiment at Fermilab, we present a model independent partial-wave analysis of the K-π+ S-wave amplitude from the decay D+ → K-π+π+. The S-wave is a generic complex function to be determined directly from the data fit. The P- and D-waves are parameterized by a sum of Breit-Wigner amplitudes. The measurement of the S-wave amplitude covers the whole elastic range of the K-π+ system.
[en] Expressions for the nucleon wave functions in the covariant spectator theory (CST) are derived. The nucleon is described as a system with a off-mass-shell constituent quark, free to interact with an external probe, and two spectator constituent quarks on their mass shell. Integrating over the internal momentum of the on-mass-shell quark pair allows us to derive an effective nucleon wave function that can be written only in terms of the quark and diquark (quark-pair) variables. The derived nucleon wave function includes contributions from S, P and D-waves.
[en] We develop a simple pairing theory of superconductivity in strongly correlated d-wave superconductors for up to a moderate strength of disorder. Our description implements the key ideas of Anderson, originally proposed for disordered s-wave superconductors, but in addition takes care of the inherent strong electronic repulsion in these compounds, as well as the inhomogeneities. We first obtain the self-consistent one-particle states, that capture the effects of disorder exactly, and strong correlations using Gutzwiller approximation. These ‘normal states’ (at zero temperature) when coupled through BCS-type pairing attractions, produces results which are nearly identical to those from a more sophisticated Gutzwiller augmented Bogoliubov-de Gennes analysis.
[en] For studying nonequilibrium dynamics of d-wave superconductors, we have constructed a nonequilibrium DMFT+FLEX method with a novel full-SU(2) slave-boson impurity-solver. An advantage of the method is that it can treat multiple phases on an equal footing for the Hubbard model on bipartite lattices. With the method, we expect to deal with the competition between antiferromagnetic and superconducting phases and to shed some light on the pseudogap physics with a slave-particle decomposition.
[en] The dynamics of a 2D d-wave BCS superconductor driven out-of-equilibrium by a perpendicularly-impinging polarized laser pulse is analyzed on varying the laser pulse characteristics. The observed effects include: oscillations both in the amplitude and in the phase of the superconducting order parameter, suppression of the superconductivity, but also its enhancement with a strong dependence on all varying parameters and, in particular, on the polarization in plane of the applied vector potential and on the value of its frequency. This study opens up the possibility to distinguish very clearly the behavior of the nodal and anti-nodal non-thermal excitations and to tackle some of the puzzling results of the current experimental scenario in the field.
[en] An accurate calculation of electron - hydrogen scattering at low energies has been carried out, employing the algebraic coupled-state method and a 13-state (5s, 5p, 2d, 1f) coupling scheme. A very narrow 3De resonance has been seen below the n=2 H excitation threshold for the first time in the present calculation. The position and width of the resonance were found to be of 0.749996057255 Ryd and 4.56x10-11 Ryd, respectively. (author). Letter-to-the-editor
[en] The author shows in this paper an interesting relation between elementary and topological excitations in the antiferromagnetic and d-wave superconducting phases of the t-J model at two dimensions. The topological spin and charge excitations in one phase have the same dynamics as elementary excitations in the other phase, except the appearance of energy gaps. Moreover, the transition from one phase to another can be described as a quantum disordering transition associated with the topological excitations. Based on the above picture, a plausible phase diagram of t-J model is constructed
[en] We introduce a new kind of numerical method to treat strongly correlated fermionic/electronic systems. By combining Grassmann algebra with tensor network/tensor product state methods, we may obtain methods that are general, unbiased, and highly effective. We will show benchmark GMERA calculations and new developments in the study of the t-J model. (authors)