Effect Of Gravitational Interactions Research Articles

Neutrino Oscillation Caused by Spacetime Geometry

Effects of gravitational interaction are generally neglected in particle physics. A first order formulation of gravity is presented to include gravity in Quantum Mechanical Lagrangian of fermions. It is seen that fermions minimally coupled to gravity gives rise to a torsionless effective theory with a quartic interaction. After passing through a thermal background the most generic form of contortion contributes to neutrino effective mass. This effective mass can change the current oscillation parameters.

Possible Astrophysical Effects of Gravitational Interaction of a Scalar Field Within the Framework of the Affine-Metric Theory of Gravitation

A gravitational interaction of a scalar field with conformal coupling \( n\frac{R}{6}{\upvarphi}^2 \) (n = const) is considered within the framework of the affine-metric theory of gravitation, with the interaction with torsion and nonmetricity taken into account. It is shown that for different values of the constant n different forms of nonlinearities are induced in the scalar field and, in particular, for n = –1 a nonlinearity corresponding to the potential of the axion field is induced. Possible astrophysical consequences of such an effect are considered.

The generalized uncertainty relation and the quantum entropy of static spherical black hole surrounded by quintessence due to spin fields

By using the brick-wall model, the quantum entropies of static spherical black hole surrounded by quintessence due to the Weyl neutrino, electromagnetic, massless Rarita–Schwinger, and gravitational fields for the source-free case are investigated from a generalized uncertainty relation. It is shown that in addition to the usual quadratically and logarithmically divergent terms, there exist additional quadratic, biquadratic, and logarithmic divergences at ultraviolet σ → 0, which not only depend on the black hole characteristics but also on the spins of the fields and the gravity correction factor. These additional terms describe the contribution of the quantum fields to the entropy and the effect of gravitational interactions on it. After the smallest length scale is taken into account, we find that the contribution of the gravitational interactions to the entropy is larger than the usual dominant term and becomes a part of the whole dominant term, so it is very important and cannot be neglected.

Theoretical models of planetary system formation: mass vs. semi-major axis

Planet formation models have been developed during the last years in order to try to reproduce the observations of both the solar system, and the extrasolar planets. Some of these models have partially succeeded, focussing however on massive planets, and for the sake of simplicity excluding planets belonging to planetary systems. However, more and more planets are now found in planetary systems. This tendency, which is a result of both radial velocity, transit and direct imaging surveys, seems to be even more pronounced for low mass planets. These new observations require the improvement of planet formation models, including new physics, and considering the formation of systems. In a recent series of papers, we have presented some improvements in the physics of our models, focussing in particular on the internal structure of forming planets, and on the computation of the excitation state of planetesimals, and their resulting accretion rate. In this paper, we focus on the concurrent effect of the formation of more than one planet in the same protoplanetary disc, and show the effect, in terms of global architecture and composition of this multiplicity. We use a N-body calculation including collision detection to compute the orbital evolution of a planetary system. Moreover, we describe the effect of competition for accretion of gas and solids, as well as the effect of gravitational interactions between planets. We show that the masses and semi-major axis of planets are modified by both the effect of competition and gravitational interactions. We also present the effect of the assumed number of forming planets in the same system (a free parameter of the model), as well as the effect of the inclination and eccentricity damping.

Early evolution of the birth cluster of the solar system

The solar system was most likely born in a star cluster containing at least 1000 stars. It is highly probable that this cluster environment influenced various properties of the solar system like its chemical composition, size and the orbital parameters of some of its constituting bodies. In the Milky Way, clusters with more than 2000 stars only form in two types - starburst clusters and leaky clusters - each following a unique temporal development in the mass-radius plane. The aim is here to determine the encounter probability in the range relevant to solar system formation for starburst or leaky cluster environments as a function of cluster age. N-body methods are used to investigate the cluster dynamics and the effect of gravitational interactions between cluster members on young solar-type stars surrounded by discs. Using the now available knowledge of the cluster density at a given cluster age it is demonstrated that in starburst clusters the central densities over the first 5Myr are so high (initially > 10^5 Msun pc^{-3}) that hardly any discs with solar system building potential would survive this phase. This makes a starburst clusters an unlikely environment for the formation of our solar system. Instead it is highly probable that the solar system formed in a leaky cluster (often classified as OB association). It is demonstrated that an encounter determining the characteristic properties existing in our solar systems most likely happened very early on (< 2Myr) in its formation history and that after 5Myr the likelihood of a solar-type star experiencing such an encounter in a leaky cluster is negligible even if it was still part of the bound remnant. This explains why the solar system could develop and maintain its high circularity later in its development.

Effects of Gravitational Interactions on Asteroid Spin States

We demonstrate that mutual gravitational interactions between an asteroid and a planet or another asteroid can play an important role in shaping an asteroid's spin state. We focus on two situations that asteroids may encounter during their lifetimes. The first is the environment after creation from a disrupted parent asteroid, when there may be many asteroid fragments interacting gravitationally with each other before their mutual escape. The other is the interaction between an asteroid and a planet during a hyperbolic flyby. In each case the mutual gravitational interaction can alter the asteroid's spin state. We derive analytical descriptions of the effects and perform numerical simulations to explore the interactions and to give examples. The net effect of many small interactions, taken in isolation, is to cause the asteroid to spin at a faster rate—although this must be balanced against all other effects that influence spin rates. Conversely, the effect of a single, strong interaction can fundamentally change an asteroid's spin state, causing it to tumble and significantly increasing or decreasing its overall angular momentum. We simulate interactions of a sphere of arbitrary mass with Toutatis and find that these types of gravitational interactions can provide partial explanations for the current Toutatis rotational state.

The effect of gravitational interaction on classical fields: A hamilton-dirac analysis

We use the Hamilton-Dirac 3 + 1 analysis to clarify the effect of a dynamic gravitational interaction on “higher spin” or “derivative-coupled” fields. We find that when the non-gravitationally coupled version of a given field theory has constraints, the introduction of a gravitational interaction tends to destroy some of them, in a predictable way. The loss of these constraints leads to discontinuities in the number of degrees of freedom in such field theories when one passes from dynamic gravitational coupling to the special relativistic flat space limit. We also find, working from the 3 + 1 point of view, that the gravitationally coupled higher spin theories tend to have evolution singularities when certain of the field components pass through zero. Both the degrees of freedom discontinuities and the evolution singularties cause problems with the special relativistic correspondence principle limit for the higher spin fields with constraints.

The effect of gravitational interaction on classical fields: a Hamilton-Dirac analysis: James A. Isenberg and James M. Nester. Department of Physics and Astronomy, University of Maryland, College Park, Maryland 20742

The effect of gravitational interaction on classical fields: a Hamilton-Dirac analysis: James A. Isenberg and James M. Nester. Department of Physics and Astronomy, University of Maryland, College Park, Maryland 20742