Effects of Bose-Einstein Condensation on forces among bodies sitting in a boson heat bath

We explore the consequences of Bose-Einstein condensation on two-scalar-exchange mediated forces among bodies that sit in a boson gas. We find that below the condensation temperature the range of the forces becomes infinite while it is finite at temperatures above condensation.Comment: 10 pages, 2 figure

Gossip on Weighted Networks

We investigate how suitable a weighted network is for gossip spreading. The proposed model is based on the gossip spreading model introduced by Lind et.al. on unweighted networks. Weight represents "friendship." Potential spreader prefers not to spread if the victim of gossip is a "close friend". Gossip spreading is related to the triangles and cascades of triangles. It gives more insight about the structure of a network. We analyze gossip spreading on real weighted networks of human interactions. 6 co-occurrence and 7 social pattern networks are investigated. Gossip propagation is found to be a good parameter to distinguish co-occurrence and social pattern networks. As a comparison some miscellaneous networks and computer generated networks based on ER, BA, WS models are also investigated. They are found to be quite different than the human interaction networks.Comment: 8 pages, 4 figures, 1 tabl

Atomic electric dipole moments of He and Yb induced by nuclear Schiff moments

We have calculated the atomic electric dipole moments (EDMs) d of ^3He and ^{171}Yb induced by their respective nuclear Schiff moments S. Our results are d(He)= 8.3x10^{-5} and d(Yb)= -1.9 in units 10^{-17}S/(e{fm}^3)e cm. By considering the nuclear Schiff moments induced by the parity and time-reversal violating nucleon-nucleon interaction we find d(^{171}Yb)~0.6d(^{199}Hg). For ^3He the nuclear EDM coupled with the hyperfine interaction gives a larger atomic EDM than the Schiff moment. The result for ^3He is required for a neutron EDM experiment that is under development, where ^3He is used as a comagnetometer. We find that the EDM for He is orders of magnitude smaller than the neutron EDM. The result for Yb is needed for the planning and interpretation of experiments that have been proposed to measure the EDM of this atom.Comment: 4 page

Local Fields without Restrictions on the Spectrum of 4-Momentum Operator and Relativistic Lindblad Equation

Quantum theory of Lorentz invariant local scalar fields without restrictions on 4-momentum spectrum is considered. The mass spectrum may be both discrete and continues and the square of mass as well as the energy may be positive or negative. Such fields can exist as part of a hidden matter in the Universe if they interact with ordinary fields very weakly. Generalization of Kallen-Lehmann representation for propagators of these fields is found. The considered generalized fields may violate CPT- invariance. Restrictions on mass-spectrum of CPT-violating fields are found. Local fields that annihilate vacuum state and violate CPT- invariance are constructed in this scope. Correct local relativistic generalization of Lindblad equation for density matrix is written for such fields. This generalization is particulary needed to describe the evolution of quantum system and measurement process in a unique way. Difficulties arising when the field annihilating the vacuum interacts with ordinary fields are discussed.Comment: Latex 23 pages, sent to "Foundations of Physics

On CP-Odd Effects in K_L \to 2\pi and K^{\pm} \to \pi^{\pm} \pi^{\pm} \pi^{\mp} Decays Generated by Direct CP Violation

The amplitudes of the K^{\pm} \to 3\pi and K \to 2\pi decays are expressed in terms of different combinations of one and the same set of CP-conserving and CP-odd parameters. Extracting the magnitudes of these parameters from the data on K \to 2\pi decays, we estimate an expected CP-odd difference between the values of the slope parameters g^+ and g^- of the energy distributions of "odd" pions in K^+ \to \pi^+\pi^+\pi^- and K^- \to \pi^-\pi^-\pi^+ decays.Comment: 12 pages, no figure

Dynamical Casimir-Polder interaction between an atom and surface plasmons

We investigate the time-dependent Casimir-Polder potential of a polarizable two-level atom placed near a surface of arbitrary material, after a sudden change in the parameters of the system. Different initial conditions are taken into account. For an initially bare ground-state atom, the time-dependent Casimir-Polder energy reveals how the atom is "being dressed" by virtual, matter-assisted photons. We also study the transient behavior of the Casimir-Polder interaction between the atom and the surface starting from a partially dressed state, after an externally induced change in the atomic level structure or transition dipoles. The Heisenberg equations are solved through an iterative technique for both atomic and field operators in the medium-assisted electromagnetic field quantization scheme. We analyze in particular how the time evolution of the interaction energy depends on the optical properties of the surface, in particular on the dispersion relationof surface plasmon polaritons. The physical significance and the limits of validity of the obtained results are discussed in detail.Comment: 12 pages, 8 figure

Atomic Electric Dipole Moments: The Schiff Theorem and Its Corrections

Searches for the permanent electric dipole moments (EDMs) of diamagnetic atoms provide powerful probes of CP-violating hadronic and semileptonic interactions. The theoretical interpretation of such experiments, however, requires careful implementation of a well-known theorem by Schiff that implies a vanishing net EDM for an atom built entirely from point-like, nonrelativistic constituents that interact only electrostatically. Any experimental observation of a nonzero atomic EDM would result from corrections to the point-like, nonrelativistic, electrostatic assumption. We reformulate Schiff's theorem at the operator level and delineate the electronic and nuclear operators whose atomic matrix elements generate corrections to "Schiff screening". We obtain a form for the operator responsible for the leading correction associated with finite nuclear size -- the so-called "Schiff moment" operator -- and observe that it differs from the corresponding operator used in previous Schiff moment computations. We show that the more general Schiff moment operator reduces to the previously employed operator only under certain approximations that are not generally justified. We also identify other corrections to Schiff screening that may not be included properly in previous theoretical treatments. We discuss practical considerations for obtaining a complete computation of corrections to Schiff screening in atomic EDM calculations.Comment: 31 pages, 2 figures, typeset by REVTe