Comment on "Order parameter of A-like 3He phase in aerogel"

We argue that the inhomogeneous A-phase in aerogel is energetically more preferable than the "robust" phase suggested by I. A. Fomin, JETP Lett. 77, 240 (2003); cond-mat/0302117 and cond-mat/0401639.Comment: 2 page

Bidimensionality of Geometric Intersection Graphs

Let B be a finite collection of geometric (not necessarily convex) bodies in the plane. Clearly, this class of geometric objects naturally generalizes the class of disks, lines, ellipsoids, and even convex polygons. We consider geometric intersection graphs GB where each body of the collection B is represented by a vertex, and two vertices of GB are adjacent if the intersection of the corresponding bodies is non-empty. For such graph classes and under natural restrictions on their maximum degree or subgraph exclusion, we prove that the relation between their treewidth and the maximum size of a grid minor is linear. These combinatorial results vastly extend the applicability of all the meta-algorithmic results of the bidimensionality theory to geometrically defined graph classes

A New World Average Value for the Neutron Lifetime

The analysis of the data on measurements of the neutron lifetime is presented. A new most accurate result of the measurement of neutron lifetime [Phys. Lett. B 605 (2005) 72] 878.5 +/- 0.8 s differs from the world average value [Phys. Lett. B 667 (2008) 1] 885.7 +/- 0.8 s by 6.5 standard deviations. In this connection the analysis and Monte Carlo simulation of experiments [Phys. Lett. B 483 (2000) 15] and [Phys. Rev. Lett. 63 (1989) 593] is carried out. Systematic errors of about -6 s are found in each of the experiments. The summary table for the neutron lifetime measurements after corrections and additions is given. A new world average value for the neutron lifetime 879.9 +/- 0.9 s is presented.Comment: 27 pages, 13 figures; Fig.13 update

Towards Field Theory in Spaces with Multivolume Junctions

We consider a spacetime formed by several pieces having common timelike boundary which plays the role of a junction between them. We establish junction conditions for fields of various spin and derive the resulting laws of wave propagation through the junction, which turn out to be quite similar for fields of all spins. As an application, we consider the case of multivolume junctions in four-dimensional spacetime that may arise in the context of the theory of quantum creation of a closed universe on the background of a big mother universe. The theory developed can also be applied to braneworld models and to the superstring theory.Comment: 20 pages, 3 figures, revtex; published versio

Photoluminescence of tetrahedral quantum-dot quantum wells

Taking into account the tetrahedral shape of a quantum dot quantum well (QDQW) when describing excitonic states, phonon modes and the exciton-phonon interaction in the structure, we obtain within a non-adiabatic approach a quantitative interpretation of the photoluminescence (PL) spectrum of a single CdS/HgS/CdS QDQW. We find that the exciton ground state in a tetrahedral QDQW is bright, in contrast to the dark ground state for a spherical QDQW.Comment: 4 pages, 2 figure

Inversion of Sequence of Diffusion and Density Anomalies in Core-Softened Systems

In this paper we present a simulation study of water-like anomalies in core-softened system introduced in our previous publications. We investigate the anomalous regions for a system with the same functional form of the potential but with different parameters and show that the order of the region of anomalous diffusion and the region of density anomaly is inverted with increasing the width of the repulsive shoulder.Comment: 8 pages, 10 figure

Core-Softened System With Attraction: Trajectory Dependence of Anomalous Behavior

In the present article we carry out a molecular dynamics study of the core-softened system and show that the existence of the water-like anomalies in this system depends on the trajectory in $P-\rho-T$ space along which the behavior of the system is studied. For example, diffusion and structural anomalies are visible along isotherms as a function of density, but disappears along the isochores and isobars as a function of temperature. On the other hand, the diffusion anomaly may be seen along adiabats as a function of temperature, density and pressure. It should be noted that it may be no signature of a particular anomaly along a particular trajectory, but the anomalous region for that particular anomaly can be defined when all possible trajectories in the same space are examined (for example, signature of diffusion anomaly is evident through the crossing of different isochors. However, there is no signature of diffusion anomaly along a particular isochor). We also analyze the applicability of the Rosenfeld entropy scaling relations to this system in the regions with the water-like anomalies. It is shown that the validity of the Rosenfeld scaling relation for the diffusion coefficient also depends on the trajectory in the $P-\rho-T$ space along which the kinetic coefficients and the excess entropy are calculated.Comment: 16 pages, 21 figures. arXiv admin note: this contains much of the content of arXiv:1010.416

Optical spectra of quantum dots: effects of non-adiabaticity

It is shown that in many cases an adequate description of optical spectra of semiconductor quantum dots requires a treatment beyond the commonly used adiabatic approximation. We have developed a theory of phonon-assisted optical transitions in semiconductor quantum dots, which takes into account non-adiabaticity of the exciton-phonon system. Effects of non-adiabaticity lead to a mixing of different exciton and phonon states that provides a key to the understanding of surprisingly high intensities of phonon satellites observed in photoluminescence spectra of quantum dots. A breakdown of the adiabatic approximation gives an explanation also for discrepancies between the serial law, observed in multi-phonon optical spectra of some quantum dots, and the Franck-Condon progression, prescribed by the adiabatic approach.Comment: 4 pages, 3 figures, E-mail addresses: [email protected], [email protected], [email protected], [email protected], [email protected]

Stable vortex-antivortex molecules in mesoscopic superconducting triangles

A thermodynamically stable vortex-antivortex pattern has been revealed in mesoscopic type I superconducting triangles, contrary to type II superconductors where similar patterns are unstable. The stable vortex-antivortex "molecule" appears due to the interplay between two factors: a repulsive vortex-antivortex interaction in type I superconductors and the vortex confinement in the triangle.Comment: 5 pages, 4 figures, E-mail addresses: [email protected], [email protected], [email protected], [email protected]

Generalized van der Waals theory of liquid-liquid phase transitions

In the framework of the thermodynamic perturbation theory for fluids we study how the phase diagram of an isotropic repulsive soft-core attractive potential, where a liquid-liquid phase transition exists in addition to the standard gas-liquid phase transition, changes by varying the parameters of the potential. We show that existence of the liquid-liquid transition is determined by the interplay of the parameters of the potential and the structure of a reference liquid.Comment: 5 pages, 6 figure