Features and stability analysis of non-Schwarzschild black hole in quadratic gravity

Black holes are found to exist in gravitational theories with the presence of quadratic curvature terms and behave differently from the Schwarzschild solution. We present an exhaustive analysis for determining the quasinormal modes of a test scalar field propagating in a new class of black hole backgrounds in the case of pure Einstein-Weyl gravity. Our result shows that the field decay of quasinormal modes in such a non-Schwarzschild black hole behaves similarly to the Schwarzschild one, but the decay slope becomes much smoother due to the appearance of the Weyl tensor square in the background theory. We also analyze the frequencies of the quasinormal modes in order to characterize the properties of new back holes, and thus, if these modes can be the source of gravitational waves, the underlying theories may be testable in future gravitational wave experiments. We briefly comment on the issue of quantum (in)stability in this theory at linear order.Comment: 18 pages, 4 figures, 1 table, several references added, version published on JHE

A New Trigonometrically Fitted Two-Derivative Runge-Kutta Method for the Numerical Solution of the Schrödinger Equation and Related Problems

A new trigonometrically fitted fifth-order two-derivative Runge-Kutta method with variable nodes is developed for the numerical solution of the radial Schrödinger equation and related oscillatory problems. Linear stability and phase properties of the new method are examined. Numerical results are reported to show the robustness and competence of the new method compared with some highly efficient methods in the recent literature

Hadron models and related New Energy issues

The present book covers a wide-range of issues from alternative hadron models to their likely implications in New Energy research, including alternative interpretation of lowenergy reaction (coldfusion) phenomena. The authors explored some new approaches to describe novel phenomena in particle physics. M Pitkanen introduces his nuclear string hypothesis derived from his Topological Geometrodynamics theory, while E. Goldfain discusses a number of nonlinear dynamics methods, including bifurcation, pattern formation (complex GinzburgLandau equation) to describe elementary particle masses. Fu Yuhua discusses a plausible method for prediction of phenomena related to New Energy development. F. Smarandache discusses his unmatter hypothesis, and A. Yefremov et al. discuss Yang-Mills field from Quaternion Space Geometry. Diego Rapoport discusses theoretical link between Torsion fields and Hadronic Mechanic. A.H. Phillips discusses semiconductor nanodevices, while V. and A. Boju discuss Digital Discrete and Combinatorial methods and their likely implications in New Energy research. Pavel Pintr et al. describe planetary orbit distance from modified Schrödinger equation, and M. Pereira discusses his new Hypergeometrical description of Standard Model of elementary particles. The present volume will be suitable for researchers interested in New Energy issues, in particular their link with alternative hadron models and interpretation

Numerical aspects of black hole superradiance

In this work we explore a numerical technique, based on the spherical harmonic decomposition and the discretization of the radial coordinate through Čebyšëv polynomial interpolation, for the computation of quasi-bound states of linear massive scalar and vector perturbations in spinning black hole spacetimes in General Relativity. The aim is studying black hole superradiant instabilities, an energy-extraction mechanism triggered by the presence of massive bosonic fields near black holes, which finds wide applications in constraining scenarios beyond Standard Model and General Relativity. This method does not rely on any separation ansätze, thus it can have wide applications. Consequently we extend the technique so that it can be applied also to the computation of massive tensor quasi-bound states in spinning black holes in General Relativity, whose separability ansatz is currently unknown. We also apply it to spinning black holes in scalar-tensor theory non-linearly interacting with plasma, wherein the massless scalar perturbations acquires an effective mass, finding a novel way for constraining scalar-tensor theories

Development of a machine learning potential for nucleotides in water

Recent experimental research showed that nucleotides, under favorable conditions of temperature and concentration, can self-assemble into liquid crystals. The mechanism involves the stacking of nucleotides into columnar aggregates. It has been proposed that this ordered structure can favor the polymerization of long nucleotide chains, which is a fundamental step toward the so called “RNA world”. In this thesis, starting from ab initio molecular dynamics simulations, at the density func- tional theory level, an all-atom potential for nucleotides in water, based on an implicit neural network representation, has been developed. Its stability and accuracy have been tested and its predictions on simple model systems have been compared with data generated both ab initio and using currently available empirical force field for nucleic acids