The decoupling limit of Multi-Gravity: Multi-Galileons, Dualities and More

In this paper we investigate the decoupling limit of a particular class of multi-gravity theories, i.e. of theories of interacting spin-2 fields. We explicitly compute the interactions of helicity-0 modes in this limit, showing that they take on the form of multi-Galileons and dual forms. In the process we extend the recently discovered Galileon dualities, deriving a set of new multi-Galileon dualities. These are also intrinsically connected to healthy, but higher-derivative, multi-scalar field theories akin to `beyond Horndeski' models.Comment: 41 pages, 2 figure

Strong-coupling scales and the graph structure of multi-gravity theories

In this paper we consider how the strong-coupling scale, or perturbative cutoff, in a multi-gravity theory depends upon the presence and structure of interactions between the different fields. This can elegantly be rephrased in terms of the size and structure of the `theory graph' which depicts the interactions in a given theory. We show that the question can be answered in terms of the properties of various graph-theoretical matrices, affording an efficient way to estimate and place bounds on the strong-coupling scale of a given theory. In light of this we also consider the problem of relating a given theory graph to a discretised higher dimensional theory, a la dimensional deconstruction.Comment: 23 pages, 7 figures; v2: additional references included, and minor typos corrected; version published in JHE

Darkness on the Edge of Town: How Entitlements Theory Can Shine A Light on Termination of Transfers in Sound Recordings

When Congress overhauled the Copyright Act in 1976, itcreated the device of termination of transfers to protectauthors of copyrighted works from unremunerativetransfers. The scheme seemed straightforward, buttechnology has created problems the Act\u27s drafters nevercould have anticipated. In particular, the application oftermination of transfers to sound recordings in 1976 waslittle more than a shadow of uncertainty not worth dealingwith at the time. But that shadow has become a creepingdarkness, and no one seems sure how to clear it.Now the darkness is here. Next year, artists like BruceSpringsteen and Bob Dylan will attempt for the first timeto recover the rights in their recordings, and record labelswill not give up without a fight. Who will win is unclearunder the statute, and Congress seems unlikely to clarifythe matter-but the darkness need not remain. Thequestion whether musical artists can terminate their transfers is really a question about who, between theartists and labels, the law should vest with an entitlementin the future interest in the copyright. Accordingly, thisNote turns to entitlements theory to examine howtermination alters the parties\u27 bargaining positions inways that implicate efficiency and copyright\u27s normativegoals. In so doing, it shines new light on the problem andshows courts and legislators a path through the darkness

Cycles of interactions in multi-gravity theories

In this paper we study multi-gravity (multi-metric and multi-vielbein) theories in the presence of cycles of interactions (cycles in the so-called `theory graph'). It has been conjectured that in multi-metric theories such cycles lead to the introduction of a ghost-like instability, which, however, is absent in the multi-vielbein version of such theories. In this paper we answer this question in the affirmative by explicitly demonstrating the presence of the ghost in such multi-metric theories in the form of dangerous higher derivative terms in the decoupling limit Lagrangian; we also explain why these terms are absent in the vielbein version of these theories. Finally we discuss the ramifications of our result on the dimensional deconstruction paradigm, which would seek an equivalence between such theories and a truncated Kaluza-Klein theory, and find that the impediment to taking the continuum limit due to a low strong-coupling scale is exacerbated by the presence of the ghost, when these theories are constructed using metrics.Comment: 25 pages; v2: corrected an error in section 5.3.1 which changes slightly the conclusions of that subsection; expanded section 6.1 to include derivation of the scaling of the cutoff; version published in JHE

Nickel biopathways in tropical nickel hyperaccumulating trees from Sabah (Malaysia)

The extraordinary level of accumulation of nickel (Ni) in hyperaccumulator plants is a consequence of specific metal sequestering and transport mechanisms, and knowledge of these processes is critical for advancing an understanding of transition element metabolic regulation in these plants. The Ni biopathways were elucidated in three plant species, Phyllanthus balgooyi, Phyllanthus securinegioides (Phyllanthaceae) and Rinorea bengalensis (Violaceae), that occur in Sabah (Malaysia) on the Island of Borneo. This study showed that Ni is mainly concentrated in the phloem in roots and stems (up to 16.9% Ni in phloem sap in Phyllanthus balgooyi) in all three species. However, the species differ in their leaves - in P. balgooyi the highest Ni concentration is in the phloem, but in P. securinegioides and R. bengalensis in the epidermis and in the spongy mesophyll (R. bengalensis). The chemical speciation of Ni(2+) does not substantially differ between the species nor between the plant tissues and transport fluids, and is unambiguously associated with citrate. This study combines ion microbeam (PIXE and RBS) and metabolomics techniques (GC-MS, LC-MS) with synchrotron methods (XAS) to overcome the drawbacks of the individual techniques to quantitatively determine Ni distribution and Ni(2+) chemical speciation in hyperaccumulator plants.Antony van der Ent, Damien L. Callahan, Barry N. Noller, Jolanta Mesjasz-Przybylowicz, Wojciech J. Przybylowicz, Alban Barnabas and Hugh H. Harri