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Register a new userIdentifying resonances with wave-packet dynamics
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A new method for the study of resonant behavior - using wave-packet dynamics - is presented, based on the powerful window operator technique. The method is illustrated and quantified by application to the astrophysically-important example of low-energy $^{12}$C + $^{12}$C collisions. For this selected, potential model test case, the technique is shown to provide both resonance energies and widths in agreement with alternative methods, such as complex-energy scattering-matrix pole searches and scattering phase-shift analyses. The method has a more general capability to study resonance phenomena across disciplines, that involve particles temporarily trapped by potential pockets.
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We consider semiclassical higher-order wave packet solutions of the Schrodinger equation with phase vortices. The vortex line is aligned with the propagation direction, and the wave packet carries a well-defined orbital angular momentum (OAM) $hbar l$ ($l$ is the vortex strength) along its main linear momentum. The probability current coils around momentum in such OAM states of electrons. In an electric field, these states evolve like massless particles with spin $l$. The magnetic-monopole Berry curvature appears in momentum space, which results in a spin-orbit-type interaction and a Berry/Magnus transverse force acting on the wave packet. This brings about the OAM Hall effect. In a magnetic field, there is a Zeeman interaction, which, can lead to more complicated dynamics.
It is well known that the Gaussian wave packet dynamics can be written in terms of Hamilton equations in the extended phase space that is twice as large as in the corresponding classical system. We construct several generalizations of this approach that include non-Gausssian wave packets. These generalizations lead to the further extension of the phase space while retaining the Hamilton structure of the equations of motion. We compare the Gaussian dynamics with these non-Gaussian extensions for a particle with the quartic potential.
We investigate theoretically electron dynamics under a VUV attosecond pulse train which has a controlled phase delay with respect to an additional strong infrared laser field. Using the strong field approximation and the fact that the attosecond pulse is short compared to the excited electron dynamics, we arrive at a minimal analytical model for the kinetic energy distribution of the electron as well as the photon absorption probability as a function of the phase delay between the fields. We analyze the dynamics in terms of electron wave packet replicas created by the attosecond pulses. The absorption probability shows strong modulations as a function of the phase delay for VUV photons of energy comparable to the binding energy of the electron, while for higher photon energies the absorption probability does not depend on the delay, in line with the experimental observations for helium and argon, respectively.
We present a program to simulate the dynamics of a wave packet interacting with a time-dependent potential. The time-dependent Schrodinger equation is solved on a one-, two-, or three-dimensional spatial grid using the split operator method. The program can be compiled for execution either on a single processor or on a distributed-memory parallel computer.
We study the strange vector meson ($K^*, bar K^*$) dynamics in relativistic heavy-ion collisions based on the microscopic Parton-Hadron-String Dynamics (PHSD) transport approach which incorporates partonic and hadronic degrees-of-freedom, a phase transition from hadronic to partonic matter - Quark-Gluon-Plasma (QGP) - and a dynamical hadronization of quarks and antiquarks as well as final hadronic interactions. We investigate the role of in-medium effects on the $K^*, bar K^*$ meson dynamics by employing Breit-Wigner spectral functions for the $K^*$s with self-energies obtained from a self-consistent coupled-channel G-matrix approach. Furthermore, we confront the PHSD calculations with experimental data for p+p, Cu+Cu and Au+Au collisions at energies up to $sqrt{{s}_{NN}} = 200$~GeV. Our analysis shows that at relativistic energies most of the final $K^*$s (observed experimentally) are produced during the late hadronic phase, dominantly by the $K+ pi to K^*$ channel, such that the fraction of the $K^*$s from the QGP is small and can hardly be reconstructed from the final observables. The influence of the in-medium effects on the $K^*$ dynamics at RHIC energies is rather modest due to their dominant production at low baryon densities (but high meson densities), however, it increases with decreasing beam energy. Moreover, we find that the additional cut on the invariant mass region of the $K^*$ further influences the shape and the height of the final spectra. This imposes severe constraints on the interpretation of the experimental results.
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