Meng-Meng Wu | Searcharxiv

arXiv2017

Energy conditions and constraints on the generalized non-local gravity model

We study and derive the energy conditions in generalized non-local gravity, which is the modified theory of general relativity (GR) obtained by adding a term $m^{2n-2}R\Box^{-n}R$ to the Einstein-Hilbert action. Moreover, in order to get some insight on the meaning of the energy conditions, we illustrate the evolutions of four energy conditions with the model parameter $\varepsilon$ for different $n$. By analysis we give the constraints on the model parameters $\varepsilon$.

gr-qc↗

arXiv2016

Holographic paramagnetism-ferromagnetism phase transition with the nonlinear electrodynamics

In the probe limit, we investigate the nonlinear electrodynamical effects of the both exponential form and the logarithmic form on the holographic paramagnetism-ferromagnetism phase transition in the background of a Schwarzschild-AdS black hole spacetime. Moreover, by comparing the exponential form of nonlinear electrodynamics with the logarithmic form of nonlinear electrodynamics and the Born-Infeld nonlinear electrodynamics which has been presented in Ref.~\cite{Wu:2016uyj}, we find that the higher nonlinear electrodynamics correction makes the critical temperature smaller and the magnetic moment harder form in the case without external field. Furthermore, the increase of nonlinear parameter b will result in extending the period of the external magnetic field. Especially, the effect of the exponential form of nonlinear electrodynamics on the periodicity of hysteresis loop is more noticeable.

hep-th↗