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In this paper we present our point of view on correct physical interpretation of the Bel-Robinson tensor within the framework of the standard General Relativity ({bf GR}), i.e., within the framework of the {bf GR} without supplementary elements like arbitrary vector field, distinguished tetrads field or second metric. We show that this tensor arises as a consequence of the Bianchi identities and, in a natural manner, it is linked to the differences of the canonical gravitational energy-momentum calculated in normal coordinates {bf NC(P)}.
Building on earlier work, we discuss a general framework for exploring the cosmological dynamics of Higher Order Theories of Gravity. We show that once the theory of gravity has been specified, the cosmological equations can be written as a first-ord
This work is essentially a review of a new spacetime model with closed causal curves, recently presented in another paper (Class. Quantum Grav. textbf{35}(16) (2018), 165003). The spacetime at issue is topologically trivial, free of curvature singula
We exhibit a particular free subarrangement of a certain restriction of the Weyl arrangement of type $E_7$ and use it to give an affirmative answer to a recent conjecture by T.~Abe on the nature of additionally free and stair-free arrangements.
The twin group $T_n$ is a right angled Coxeter group generated by $n- 1$ involutions and having only far commutativity relations. These groups can be thought of as planar analogues of Artin braid groups. In this note, we study some properties of twin
The analysis of the LHCb data on $X(6900)$ found in the di-$jpsi$ system is performed using a momentum-dependent Flatt{e}-like parameterization. The use of the pole counting rule and spectral density function sum rule give consistent conclusions that