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No abstract available

[en] The massless limit of Fierz-Pauli field theories, describing fields with fixed mass and spin interacting with external sources, is examined. Results are obtained for spins, 1, 3/2, 2 and 3 using conventional models, and then for all half-integral spins in a relatively model-independent manner. It is found that the massless limit is smooth provided that the sources satisfy certain conditions. In the massless limit these conditions reduce to the conservation laws required by internal consistency of massless field theory. Smoothness simply requires that quantities that vanish in the massless case approach zero in a certain well-defined manner. (orig.)

[en] We study the d-dimensional Fisher solution which represents a static, spherically symmetric, asymptotically flat spacetime with a massless scalar field. The solution has two parameters, the mass M and the 'scalar charge' Σ. The Fisher solution has a naked curvature singularity which divides the spacetime manifold into two disconnected parts. The part which is asymptotically flat we call the Fisher spacetime, and another part we call the Fisher universe. The d-dimensional Schwarzschild-Tangherlini solution and the Fisher solution belong to the same theory and are dual to each other. The duality transformation acting in the parameter space (M,Σ) maps the exterior region of the Schwarzschild-Tangherlini black hole into the Fisher spacetime which has a naked timelike singularity, and interior region of the black hole into the Fisher universe, which is an anisotropic expanding-contracting universe and which has two spacelike singularities representing its 'big bang' and 'big crunch'. The big bang singularity and the singularity of the Fisher spacetime are radially weak in the sense that a 1-dimensional object moving along a timelike radial geodesic can arrive to the singularities intact. At the vicinity of the singularity the Fisher spacetime of nonzero mass has a region where its Misner-Sharp energy is negative. The Fisher universe has a marginally trapped surface corresponding to the state of its maximal expansion in the angular directions. These results and derived relations between geometric quantities of the Fisher spacetime, the Fisher universe, and the Schwarzschild-Tangherlini black hole may suggest that the massless scalar field transforms the black hole event horizon into the naked radially weak disjoint singularities of the Fisher spacetime and the Fisher universe which are 'dual to the horizon'.

[en] Event-by-event (ebe) fluctuations of hadronic patterns are investigated in terms of voids by analyzing the experimental data on 4.5, 14.5 and 60 A GeV/c "1"6O-AgBr collisions. The findings are compared with the predictions of a multi-phase transport AMPT model. Dependence of voids on phase space bin width is examined in terms of two lowest moments of ebe fluctuations of voids, 〈G_q〉 and S_q. The findings reveal that scaling exponent estimated from the observed power-law behavior of the voids may be used to characterize the various properties of hadronic phase transition. The results also rule out occurrence of second-order quark–hadron phase transition at the projectile energies considered. (author)

[en] The results of data analysis (10,11) on π meson photoproduction on nucleus 1^2C at E_γ^max = 4,5 GeV from the point of obtaining information about factorization of invariant cross section f_π (α,P_l²) are presented. It is shown that in the representation f_π (α,P_l²) ∼ f_1π (α )

[en] In this paper, we revisit the study of the leading order late time decay tails of massless scalar perturbations outside an extreme Reissner–Nordström black hole. Previous authors have analysed this problem in the time domain; we analyse the problem in the frequency domain. We first consider initial perturbations with generic regular behaviour across the horizon on characteristic surfaces. For this set-up, we reproduce some of the previous results of Sela (2016 Phys. Rev. D 93 024054) using Fourier methods. Next we consider related initial data on hypersurfaces, and present decay results at timelike infinity, near future null infinity, and near the future horizon. Along the way, using the inversion symmetry of the extreme Reissner–Nordström spacetime, we relate the higher multipole Aretakis and Newman–Penrose constants for a massless scalar in this background. (paper)

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[en] The interaction of the S=1/2 fermion field with the 2(2S+1)- component massless field is considered. New interpretation of the bispinors corresponding to the S=1 particles is proposed. The equation analogous to the Dirac oscillator is obtained. 13 refs

No abstract available