Modern Physics Letters A

We show how the motion of a charged particle near the horizon of an extreme Reissner–Nordström black hole can lead to different forms of conformal mechanics, depending on the choice of the time coordinate.

By using a tracking quintessence model we obtain that the position of the first Doppler peak in the spectrum of CMB anisotropies only depends on the topology, of the universe, Ω_k, for any value of the ratio Ω_Λ/Ω_M, so that such a dependence is perfectly valid in the range suggested by supernova observations. A prediction from the used quintessence model is also that all peaks at positions ℓ_n for n even are fully suppressed on that spectrum.

We have systematically analyzed the two-body weak radiative Λ_b→Λγ decay of bottom baryon. The weak radiative decay proceeds through W-exchange accompanied by a photon emission. Effective Lagrangian has been used for the W-exchange bremsstrahlung processes to estimate the long distance effect through pole. The short distance effect at the quark level (b→sγ) is also estimated here. With these predictions we have finally obtained the branching ratio of Λ_b→Λγ as Br(Λ_b→Λγ)=2.3×10^-10 which is in close agreement with the experimental results.

Based on the Walecka model, we mainly discuss how the effective mass of nucleon changes under the condition of phase transition. We indicate that the effective mass of nucleon changes non-monotonically with temperature and chemical potential when the phase transition occurs.

Atmospheric free fall with quadratic resistance when considered from the point of view of the strictly isospectral construction of supersymmetric quantum mechanics is a powerful analogy for the class of Darboux cosmological fluids that we introduced in a previous work. Here, using this analogy, it is shown that the possible accelerating cosmological effects are due to the quadratic negative friction properties with which the Darboux fluids are endowed through the mathematical construction.

We examine the correlation between compact radio quasars (redshifts in the range z=0.3–2.2) and the arrival direction of ultrahigh energy cosmic rays forming clusters. Our Monte Carlo simulation reveals a statistically significant correlation on the AGASA sample: the chance probability of this effect being less than 1%. The implications of this result on the origin of ultrahigh energy cosmic rays are discussed.

The continuity, equation relating the change in time of the position probability density to the gradient of the probability current density is generalized to PT-symmetric quantum mechanics. The normalization condition of eigenfunctions is modified in accordance with this new conservation law and illustrated with some detailed examples.