01 14 2 v 1 1 9 Ja n 20 07 No nonlocal box is universal

nt - p h / 07 01 14 2 v 1 1 9 Ja n 20 07 No nonlocal box is universal Frédéric Dupuis

We show that standard nonlocal boxes, also known as PopescuRohrlich machines, are not sufficient to simulate any nonlocal correlations that do not allow signalling. This was known in the multipartite scenario, but we extend the result to the bipartite case. We then generalize this result further by showing that no finite set containing any finite-output-alphabet nonlocal boxes can be a universa...

ua nt - p h / 06 09 16 6 v 1 2 1 Se p 20 06 No nonlocal box with uniform outputs is universal Frédéric

We show that standard nonlocal boxes, also known as PopescuRohrlich machines, are not sufficient to simulate any nonlocal correlations that do not allow signalling. This was known in the multipartite scenario, but we extend the result to the bipartite case. We then generalize this result further by showing that no finite set containing any finite-output-alphabet nonlocal boxes with uniform outp...

ar X iv : h ep - t h / 05 01 14 3 v 1 1 9 Ja n 20 05 CCNY - HEP - 05 / 1 January 2005 A Note on MHV Amplitudes for Gravitons

We show how the maximally helicity violating (MHV) scattering amplitudes for gravitons can be related to current correlators and vertex operators in twistor space. This is similar to what happens in Yang-Mills theory and raises the possibility of a direct twistor-string-like construction for N = 8 supergravity.

/ 02 01 28 9 v 1 3 0 Ja n 20 02 The η ′ → ηππ decay in U ( 3 ) chiral perturbation theory 1

ar X iv : h ep - t h / 01 01 14 8 v 1 2 3 Ja n 20 01 Multidimensional Phase Space and Sunset Diagrams

We derive expressions for the phase-space of a particle of momentum p decaying into N particles, that are valid for any number of dimensions. These are the imaginary parts of so-called 'sunset' diagrams, which we also obtain. The results are given as a series of hypergeometric functions, which terminate for odd dimensions and are also well-suited for deriving the threshold behaviour.