60 research outputs found
Temperatures of Fragment Kinetic Energy Spectra
Multifragmentation reactions without large compression in the initial state
(proton-induced reactions, reverse-kinematics, projectile fragmentation) are
examined, and it is verified quantitatively that the high temperatures obtained
from fragment kinetic energy spectra and lower temperatures obtained from
observables such as level population or isotope ratios can be understood in a
common framework.Comment: LaTeX, 7 pages, 2 figures available from autho
Adiabatic perturbation theory: from Landau-Zener problem to quenching through a quantum critical point
We discuss the application of the adiabatic perturbation theory to analyze
the dynamics in various systems in the limit of slow parametric changes of the
Hamiltonian. We first consider a two-level system and give an elementary
derivation of the asymptotics of the transition probability when the tuning
parameter slowly changes in the finite range. Then we apply this perturbation
theory to many-particle systems with low energy spectrum characterized by
quasiparticle excitations. Within this approach we derive the scaling of
various quantities such as the density of generated defects, entropy and
energy. We discuss the applications of this approach to a specific situation
where the system crosses a quantum critical point. We also show the connection
between adiabatic and sudden quenches near a quantum phase transitions and
discuss the effects of quasiparticle statistics on slow and sudden quenches at
finite temperatures.Comment: 20 pages, 3 figures, contribution to "Quantum Quenching, Annealing
and Computation", Eds. A. Das, A. Chandra and B. K. Chakrabarti, Lect. Notes
in Phys., Springer, Heidelberg (2009, to be published), reference correcte
Bose-Einstein condensates in a one-dimensional double square well: Analytical solutions of the Nonlinear Schr\"odinger equation and tunneling splittings
We present a representative set of analytic stationary state solutions of the
Nonlinear Schr\"odinger equation for a symmetric double square well potential
for both attractive and repulsive nonlinearity. In addition to the usual
symmetry preserving even and odd states, nonlinearity introduces quite exotic
symmetry breaking solutions - among them are trains of solitons with different
number and sizes of density lumps in the two wells. We use the symmetry
breaking localized solutions to form macroscopic quantum superpositions states
and explore a simple model for the exponentially small tunneling splitting.Comment: 11 pages, 11 figures, revised version, typos and references correcte
Relação entre medidas ultrassônicas e da carcaça de bubalinos Murrah abatidos em diferentes períodos de confinamento
Hyperfine-axis orientation in rhombic metal complexes from ENDOR-induced EPR and quadrupolar coupling determination
Theoretical analysis of a Brillouin switch for amplifier decoupling and prepulse suppression in short-pulse high-power laser systems
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