A short note on the Aharonov-Bohm effect

We point out that the Aharonov-Bohm effect is a 4-dimensional nonlocal geometric phenomenon. We give two examples which in 3 dimensions appear rather mysterious, but which are easily understood in 4 dimensions. We also discuss why it is integrated effects over fields (potentials) rather than the fields themselves that are important.     

Quantization in the large

A model theory is constructed that exhibits quantization on a cosmic scale. A holistic rationale for the theory is discussed. The theory incorporates a fundamental length, of cosmic size, and preserves the weak, geometrical equivalence principle. The momentum operator is an integral, nonlocal, naturally contravariant operator, in contrast to the usual quantum case. In the limit of high quantum numbers the theory reduces to classical physics, giving rise to a world which is quantized both on the microscopic and cosmic scale, each of which passes over to the usual macroscopic, continuous, classical, world in the highn limit. The theory is applied to two experimental situations, absorption lines in high-z quasars and elliptical rings around normal galaxies, with suggestive but not definitive results.     

“Haunted” measurements in quantum theory

Sometimes it is possible in quantum theory for a system to interact with another system in such a way that the information contained in the wave function becomes very scrambled and apparently incoherent. We produce an example which is exactly calculable, in which a macroscopic change is induced in the environment, and all phase information for the system is apparently lost, so that a measurement has seemingly been made. But actually, although the wave function has been badly scrambled, all the original information is still present. We call this situation one of latent order.Subsequently, the system interacts again with the environment, wiping out the macroscopic change, and the wave function once again becomes manifestly coherent. Thus the apparent measurement has been undone, and leaves no aftereffect. Thus, our measurement has disappeared without a trace. We call such a measurement a haunted measurement, and we believe that until the measurement process is rigorously understood, the concept of measurement is ambiguous. It is just not good enough to say that an amplification stage occurs somewhere in the process.We also point out the connection between the haunted measurement and delayed-choice experiments and discuss a haunted version of the Schrödinger's Cat experiment and of the Einstein-Podolsky-Rosen experiment.     

Baryon pairs production ine + e − annihilation at\sqrt s = 2.4 GeV

Search for baryon pairs production ine ⁺ e ^? annihilation at \(\sqrt s = 2386 MeV\) is reported. The data relate to a luminosity of 161 nb^?1 collected by the DM2 experiment at DCI, the Orsay colliding ring. First measurements of directe ⁺ e ^? annihilation into \(\Lambda \bar \Lambda \) and ofe ⁺ e ^?→ \(p\bar p\) at this energy are presented. First observation of a goode ⁺ e ^?→ \(n\bar n\) candidate is reported and upper limits are given fore ⁺ e ^?→ \(n\bar n, \Lambda \bar \sum ^0 + c.c.\) and \(\Sigma ^0 \bar \Sigma ^0 \) .     

Similarities and Differences Between Two‐Particle and Three‐Particle Interference

We illustrate various methods for implementing experiments that split particles into three beams, using “tritters”, or use three coherent particles (GHZ states), in order to illustrate our belief that any experiment that can be done using two particles is more interesting with three partricles.     

Cooperative behavior between oscillatory and excitable units: the peculiar role of positive coupling-frequency correlations

We study the collective dynamics of noise-driven excitable elements, so-called active rotators. Crucially here, the natural frequencies and the individual coupling strengths are drawn from some joint probability distribution. Combining a mean-field treatment with a Gaussian approximation allows us to find examples where the infinite-dimensional system is reduced to a few ordinary differential equations. Our focus lies in the cooperative behavior in a population consisting of two parts, where one is composed of excitable elements, while the other one contains only self-oscillatory units. Surprisingly, excitable behavior in the whole system sets in only if the excitable elements have a smaller coupling strength than the self-oscillating units. In this way positive local correlations between natural frequencies and couplings shape the global behavior of mixed populations of excitable and oscillatory elements.     

The Tic-Tac-Toe Theory of Gravity

The Tic-Tac-Toe theory is a qualitative, phenomenological theory that automatically explains many of the features of the universe that we see, such as dark matter and dark energy. In that sense it is a Copernican theory that gives an alternate approach, which immediately and intuitively explains phenomena,independently of any detailed dynamics, for which the explanations in accepted standard theories are usually somewhat ad-hoc.