1,721,027 research outputs found
The Accurate Mass Distribution of M87, the Giant Galaxy with Imaged Shadow of Its Supermassive Black Hole, as a Portal to New Physics
No full textBeyond Einstein: gravitational waves from extended gravity
No full textWe show that linearizing Extended Theories of Gravity, further gravitationalmodes emerge. Besides massless spin-2, also spin-0 and spin-2 massive and ghostfields have to be considered as soon as one is considering the full curvaturebudget of generic metric theories of gravity. Such additional modes give rise tofurther polarizations that could be of interest for direct detection by theforthcoming Advanced LIGO-VIRGO and other collaborations
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
An effective field theory description for extended gravity
No full textMassive gravitational modes in effective field theories can be recovered by extending general relativity and taking into account generic functions of the curvature invariants, not necessarily linear in the Ricci scalar R. In particular, adopting the minimal extension of f(R) gravity, an effective field theory with massive modes is straightforwardly recovered. This approach allows to evade shortcomings like ghosts and discontinuities if a suitable choice of expansion parameters is performed
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