Toward faithful templates for non-spinning binary black holes using the effective-one-body approach

We present an accurate approximation of the full gravitational radiation waveforms generated in the merger of non-eccentric systems of two non-spinning black holes. Utilizing information from recent numerical relativity simulations and the natural flexibility of the effective-one-body (EOB) model, we extend the latter so that it can successfully match the numerical relativity waveforms during the last stages of inspiral, merger and ringdown. By ``successfully'' here, we mean with phase differences < 8% of a gravitational-wave cycle accumulated by the end of the ringdown phase, maximizing only over time of arrival and initial phase. We obtain this result by simply adding a 4-post-Newtonian order correction in the EOB radial potential and determining the (constant) coefficient by imposing high-matching performances with numerical waveforms of mass ratios m1/m2 = 1, 3/2, 2 and 4, m1 and m2 being the individual black-hole masses. The final black-hole mass and spin predicted by the numerical simulations are used to determine the ringdown frequency and decay time of three quasi-normal-mode damped sinusoids that are attached to the EOB inspiral-(plunge) waveform at the EOB light-ring. The EOB waveforms might be tested and further improved in the future by comparison with extremely long and accurate inspiral numerical-relativity waveforms. They may already be employed for coherent searches and parameter estimation of gravitational waves emitted by non-spinning coalescing binary black holes with ground-based laser-interferometer detectors.Comment: 15 pages, 9 figure

Outliers involving the Poly(A) effect among highly-expressed genes in microarrays

BACKGROUND: The Poly(A) effect is a cross-hybridization artifact in which poly(T)-containing molecules, which are produced by the reverse transcription of a poly(A)(+ )RNA mixture, bind promiscuously to the poly(A) stretches of the DNA in microarray spots. It is customary to attempt to block such hybridization by adding poly(A) to the hybridization solution. This note describes an experiment intended to evaluate circumstances under which the blocking procedure may not have been successful. RESULTS: The experiment involves a spot-by-spot comparison between the hybridization signals obtained by hybridizing a microarray to: (1) end-labeled oligo(dT), versus, (2) cDNA prepared from muscle tissue. We found that the blocking appears to be successful for the vast majority of microarray spots, as evidenced by the weakness of the correlation between signals (1) and (2). However, we found that for microarray spots having oligo(dT) hybridization levels greater than a certain threshold, the blocking might be ineffective or incomplete, as evidenced by an exceptionally strong signal (2) whenever signal (1) is greater than the threshold. CONCLUSION: The PolyA effect may be more subtle than simply a hybridization signal that is proportional to the PolyA content of each microarray spot. It may instead be present only in spots that hybridize oligo(dT) greater than some threshold level. The strong signal generated at these "outlier" spots by cDNA probes might be due to the formation of hybridization heteropolymers

Superradiant Decay of Cyclotron Resonance of Two-Dimensional Electron Gases

We report on the observation of collective radiative decay, or superradiance, of cyclotron resonance (CR) in high-mobility two-dimensional electron gases in GaAs quantum wells using time-domain terahertz magnetospectroscopy. The decay rate of coherent CR oscillations increases linearly with the electron density in a wide range, which is a hallmark of superradiant damping. Our fully quantum mechanical theory provides a universal formula for the decay rate, which reproduces our experimental data without any adjustable parameter. These results firmly establish the many-body nature of CR decoherence in this system, despite the fact that the CR frequency is immune to electron-electron interactions due to Kohn's theorem.Comment: 5 pages, 4 figure

Novel Families of Fractional Quantum Hall States: Pairing of Composite Fermions

Fractional quantum Hall (FQH) states have recently been observed at unexpected values of the filling factor nu. Here we interpret these states as a novel family of FQH states involving pairing correlations rather than Laughlin correlations among the quasiparticles (QP's). The correlations depend upon the behavior of the QP-QP pseudopotential V_QP(L'), the interaction energy of a pair as a function of the pair angular momentum L'. This behavior, known from numerical studies of small systems, is used to demonstrate that pairing correlations give rise to FQH states at the experimentally observed values of nu.Comment: to appear in Physics Letters

The Free Will Theorem

On the basis of three physical axioms, we prove that if the choice of a particular type of spin 1 experiment is not a function of the information accessible to the experimenters, then its outcome is equally not a function of the information accessible to the particles. We show that this result is robust, and deduce that neither hidden variable theories nor mechanisms of the GRW type for wave function collapse can be made relativistic. We also establish the consistency of our axioms and discuss the philosophical implications.Comment: 31 pages, 6figure

Generalized measurements by linear elements

I give a first characterization of the class of generalized measurements that can be exactly realized on a pair of qudits encoded in indistinguishable particles, by using only linear elements and particle detectors. Two immediate results follow from this characterization. (i) The Schmidt number of each POVM element cannot exceed the number of initial particles. This rules out any possibility of performing perfect Bell-measurements for qudits. (ii) The maximum probability of performing a generalized incomplete Bell-measurement is 1/2.Comment: 4 pages. Submitted to Phys. Rev.