Faster linearizability checking via PP-compositionality

Linearizability is a well-established consistency and correctness criterion for concurrent data types. An important feature of linearizability is Herlihy and Wing's locality principle, which says that a concurrent system is linearizable if and only if all of its constituent parts (so-called objects) are linearizable. This paper presents $P$-compositionality, which generalizes the idea behind the locality principle to operations on the same concurrent data type. We implement $P$-compositionality in a novel linearizability checker. Our experiments with over nine implementations of concurrent sets, including Intel's TBB library, show that our linearizability checker is one order of magnitude faster and/or more space efficient than the state-of-the-art algorithm.Comment: 15 pages, 2 figure

Equivalence Principle tests, Equivalence theorems and New long-range forces

We discuss the possible existence of new long-range forces mediated by spin-1 or spin-0 particles. By adding their effects to those of gravity, they could lead to apparent violations of the Equivalence Principle. While the vector part in the couplings of a new spin-1 U boson involves, in general, a combination of the B and L currents, there may also be, in addition, an axial part as well. If the new force has a finite range \lambda, its intensity is proportional to 1/(\lambda^2 F^2), F being the extra U(1) symmetry-breaking scale. Quite surprisingly, particle physics experiments can provide constraints on such a new force, even if it is extremely weak, the corresponding gauge coupling being extremely small (<< 10^-19 !). An ``equivalence theorem'' shows that a very light spin-1 U boson does not in general decouple even when its gauge coupling vanishes, but behaves as a quasimassless spin-0 particle, having pseudoscalar couplings proportional to 1/F. Similarly, in supersymmetric theories, a very light spin-3/2 gravitino might be detectable as a quasi massless spin-1/2 goldstino, despite the extreme smallness of Newton's gravitational constant G_N, provided the supersymmetry-breaking scale is not too large. Searches for such U bosons in \psi and \Upsilon decays restrict F to be larger than the electroweak scale (the U actually becoming, as an axion, quasi ``invisible'' in particle physics for sufficiently large F). This provides strong constraints on the corresponding new force and its associated EP violations. We also discuss briefly new spin-dependent forces.Comment: 19 page

Statistical Test of Anarchy

"Anarchy" is the hypothesis that there is no fundamental distinction among the three flavors of neutrinos. It describes the mixing angles as random variables, drawn from well defined probability distributions dictated by the group Haar measure. We perform a Kolmogorov-Smirnov (KS) statistical test to verify whether anarchy is consistent with all neutrino data, including the new result presented by KamLAND. We find a KS probability for Nature's choice of mixing angles equal to 64%, quite consistent with the anarchical hypothesis. In turn, assuming that anarchy is indeed correct, we compute lower bounds on |U_{e3}|^2, the remaining unknown "angle" of the leptonic mixing matrix.Comment: 5 pages, 2 figures. Improved criteria for testing the hypothesis and deriving lower limits on theta_{13

Hiding Ignorance Using High Dimensions

The absence of information -- entirely or partly -- is called ignorance. Naturally, one might ask if some ignorance of a whole system will imply some ignorance of its parts. Our classical intuition tells us yes, however quantum theory tells us no: it is possible to encode information in a quantum system so that despite some ignorance of the whole, it is impossible to identify the unknown part arXiv:1011.6448. Experimentally verifying this counter-intuitive fact requires controlling and measuring quantum systems of high dimension $(d {>} 9)$. We provide this experimental evidence using the transverse spatial modes of light, a powerful resource for testing high dimensional quantum phenomenon