Damping of giant resonances in asymmetric nuclear matter

The giant collective modes in asymmetric nuclear matter are investigated within a dynamic relaxation time approximation. We derive a coupled dispersion relation and show that two sources of coupling appear: (i) a coupling of isoscalar and isovector modes due to different mean-fields acting and (ii) an explicit new coupling in asymmetric matter due to collisional interaction. We show that the latter one is responsible for a new mode arising besides isovector and isoscalar modes.Comment: Varenna conference proceeding

Nonlinear relaxation field in charged systems under high electric fields

The influence of an external electric field on the current in charged systems is investigated. The results from the classical hierarchy of density matrices are compared with the results from the quantum kinetic theory. The kinetic theory yields a systematic treatment of the nonlinear current beyond linear response. To this end the dynamically screened and field-dependent Lenard-Balescu equation is integrated analytically and the nonlinear relaxation field is calculated. The classical linear response result known as Debye - Onsager relaxation effect is only obtained if asymmetric screening is assumed. Considering the kinetic equation of one specie the other species have to be screened dynamically while the screening with the same specie itself has to be performed statically. Different other approximations are discussed and compared.Comment: language correction

The radial defocusing energy-supercritical cubic nonlinear wave equation in R^{1+5}

In this work, we consider the energy-supercritical defocusing cubic nonlinear wave equation in dimension d=5 for radially symmetric initial data. We prove that an a priori bound in the critical space implies global well-posedness and scattering. The main tool that we use is a frequency localized version of the classical Morawetz inequality, inspired by recent developments in the study of the mass and energy critical nonlinear Schr\"odinger equation.Comment: AMS Latex, 20 page

Electronic transport properties through thiophenes on switchable domains

The electronic transport of electrons and holes through stacks of $\alpha$,\ome ga-dicyano-$\beta$,$\beta$'-dibutyl- quaterthiophene (DCNDBQT) as part of a nov el organic ferroic field-effect transistor (OFFET) is investigated. The novel ap plication of a ferroelectric instead of a dielectric substrate provides the poss ibility to switch bit-wise the ferroelectric domains and to employ the polarizat ion of these domains as a gate field in an organic semiconductor. A device conta ining very thin DCNDBQT films of around 20 nm thickness is intended to be suitab le for logical as well as optical applications. We investigate the device proper ties with the help of a phenomenological model called multilayer organic light-e mitting diodes (MOLED), which was extended to transverse fields. The results sho wed, that space charge and image charge effects play a crucial role in these org anic devices

Enhancement of pairing due to the presence of resonant cavities

A correlated fermion system is considered surrounding a finite cavity with virtual levels. The pairing properties are calculated and the influence of the cavity is demonstrated. To this end the Gell-Mann and Goldberger formula is generalized to many-body systems. We find a possible enhancement of pairing temperature if the Fermi momentum times the cavity radius fulfills a certain resonance condition which suggests an experimental realization.Comment: 4 pages 2 figure

Correlated two-particle scattering on finite cavities

The correlated two-particle problem is solved analytically in the presence of a finite cavity. The method is demonstrated here in terms of exactly solvable models for both the cavity as well as the two-particle correlation where the two-particle potential is chosen in separable form. The two-particle phase shift is calculated and compared to the single-particle one. The two-particle bound state behavior is discussed and the influence of the cavity on the binding properties is calculated.Comment: Derivation shortened and corrected, 14 pages 10 figure

In-medium two-nucleon properties in high electric fields

The quantum mechanical two - particle problem is considered in hot dense nuclear matter under the influence of a strong electric field such as the field of the residual nucleus in heavy - ion reactions. A generalized Galitskii-Bethe-Salpeter equation is derived and solved which includes retardation and field effects. Compared with the in-medium properties in the zero-field case, bound states are turned into resonances and the scattering phase shifts are modified. Four effects are observed due to the applied field: (i) A suppression of the Pauli-blocking below nuclear matter densities, (ii) the onset of pairing occurs already at higher temperatures due to the field, (iii) a field dependent finite lifetime of deuterons and (iv) the imaginary part of the quasiparticle self-energy changes its sign for special values of density and temperatures indicating a phase instability. The latter effect may influence the fragmentation processes. The lifetime of deuterons in a strong Coulomb field is given explicitly.Comment: ps file + 7 figures (eps

Facebook, Being Cool, and Your Brain: What Science Tells Us

What happens in your brain when you find out that someone thinks you’re cool? Neuroscientists have recently started to investigate this by looking into how our brains process information concerning our reputation. Just a few years ago, it was discovered that when we learn that other people think highly of us, a key part of the brain’s reward system is activated [1]. The reward system is a set of interconnected brain structures that gives us a pleasurable feeling when we obtain or do things with a positive value. Getting a compliment feels good, so it makes sense that the reward system might be involved