Universality of three-body systems in 2D: parametrization of the bound states energies

Universal properties of mass-imbalanced three-body systems in 2D are studied using zero-range interactions in momentum space. The dependence of the three-particle binding energy on the parameters (masses and two-body energies) is highly non-trivial even in the simplest case of two identical particles and a distinct one. This dependence is parametrized for ground and excited states in terms of {\itshape supercircles} functions in the most general case of three distinguishable particles.Comment: 3 pages, 1 figure, published versio

Mass-imbalanced Three-Body Systems in Two Dimensions

We consider three-body systems in two dimensions with zero-range interactions for general masses and interaction strengths. The momentum-space Schr\"odinger equation is solved numerically and in the Born-Oppenheimer (BO) approximation. The BO expression is derived using separable potentials and yields a concise adiabatic potential between the two heavy particles. The BO potential is Coulomb-like and exponentially decreasing at small and large distances, respectively. While we find similar qualitative features to previous studies, we find important quantitative differences. Our results demonstrate that mass-imbalanced systems that are accessible in the field of ultracold atomic gases can have a rich three-body bound state spectrum in two dimensional geometries. Small light-heavy mass ratios increase the number of bound states. For 87Rb-87Rb-6Li and 133Cs-133Cs-6Li we find respectively 3 and 4 bound states.Comment: 17 pages, 8 figures, revised versio

Three-body bound states of two bosonic impurities immersed in a Fermi sea in 2D

We consider two identical impurities immersed in a Fermi sea for a broad range of masses and for both interacting and non-interacting impurities. The interaction between the particles is described through attractive zero-range potentials and the problem is solved in momentum space. The two impurities can attach to a fermion from the sea and form three-body bound states. The energy of these states increase as function of the Fermi momentum $k_F$, leading to three-body bound states below the Fermi energy. The fate of the states depends highly on two- and three-body thresholds and we find evidence of medium-induced Borromean-like states in 2D. The corrections due to particle-hole fluctuations in the Fermi sea are considered in the three-body calculations and we show that in spite of the fact that they strongly affect both the two- and three-body systems, the correction to the point at which the three-body states cease to exist is small.Comment: 27 pages, 10 figures, including technical appendices, published versio

Effects of dislocation density on injection and temperature sensitivity of InGaN LED emission spectra: a combined experimental and simulation approach

The aim of this paper is to describe a combined simulation and characterization activity carried out on blue LEDs grown on templates with different threading dislocation densities (TDDs)

Single-Particle Momentum Distributions of Efimov States in Mixed-Species Systems

We solve the three-body bound state problem in three dimensions for mass imbalanced systems of two identical bosons and a third particle in the universal limit where the interactions are assumed to be of zero-range. The system displays the Efimov effect and we use the momentum-space wave equation to derive formulas for the scaling factor of the Efimov spectrum for any mass ratio assuming either that two or three of the two-body subsystems have a bound state at zero energy. We consider the single-particle momentum distribution analytically and numerically and analyse the tail of the momentum distribution to obtain the three-body contact parameter. Our finding demonstrate that the functional form of the three-body contact term depends on the mass ratio and we obtain an analytic expression for this behavior. To exemplify our results, we consider mixtures of Lithium with either two Caesium or Rubium atoms which are systems of current experimental interest.Comment: 16 pages, 9 figures, 1 appendix, revised versio

Primary cosmic ray spectrum in the 10 to the 12th power - 10 to the 16th power eV energy range from the NUSEX experiment

A primary cosmic ray spectrum was derived which fits both experimental multiple muon rates and the all-nucleon flux derived from the single muon intensities underground. In the frame of the interaction model developed by Gaisser, Elbert and Stanev, it is possible to reproduce NUSEX muon data with a primary composition in which the iron spectrum is only slightly flatter than the proton one. This result rules out the popular idea that the primary composition varies drastically with increasing energy, leading to the dominance of heavier nuclei at energies 10 to the 15th power to 10 to the 16th power eV

Nucleon decay and atmospheric neutrinos in the Mont Blanc experiment

In the NUSEX experiment, during 2.8 years of operation, 31 fully contained events have been collected; 3 among them are nucleon decay candidates, while the others have been attributed to upsilon interactions. Limits on nucleon lifetime and determinations of upsilon interaction rates are presented

3D physical modeling of tsunamis generated by submerged landslides at a conical island. The role of initial acceleration

This paper presents a new set of 3D experiments aimed to gain insight on the role of the initial acceleration upon the generation process of tsunamis by submerged landslides that may occur at the flanks of conical islands. The experiments have been carried out in a large wave tank by varying the initial acceleration of the landslide model. A novel system, relying on the use of a computer controlled stepped motor, has been employed to control the motion of the landslide model. The experiments have been carried out in a parametric way by changing the initial acceleration of the landslide, aiming to reproduce different triggering mechanisms. Preliminary experimental findings confirmed the crucial role of the initial acceleration of the submerged landslide in generating tsunamis

Squeezing the Efimov effect

The quantum mechanical three-body problem is a source of continuing interest due to its complexity and not least due to the presence of fascinating solvable cases. The prime example is the Efimov effect where infinitely many bound states of identical bosons can arise at the threshold where the two-body problem has zero binding energy. An important aspect of the Efimov effect is the effect of spatial dimensionality; it has been observed in three dimensional systems, yet it is believed to be impossible in two dimensions. Using modern experimental techniques, it is possible to engineer trap geometry and thus address the intricate nature of quantum few-body physics as function of dimensionality. Here we present a framework for studying the three-body problem as one (continuously) changes the dimensionality of the system all the way from three, through two, and down to a single dimension. This is done by considering the Efimov favorable case of a mass-imbalanced system and with an external confinement provided by a typical experimental case with a (deformed) harmonic trap.Comment: 11 pages, 4 figures, comments are most welcom

Analysis of Gamma Radiation from a Radon Source: Indications of a Solar Influence

This article presents an analysis of about 29,000 measurements of gamma radiation associated with the decay of radon in a sealed container at the Geological Survey of Israel (GSI) Laboratory in Jerusalem between 28 January 2007 and 10 May 2010. These measurements exhibit strong variations in time of year and time of day, which may be due in part to environmental influences. However, time-series analysis reveals a number of periodicities, including two at approximately 11.2 year$^{-1}$ and 12.5 year$^{-1}$. We have previously found these oscillations in nuclear-decay data acquired at the Brookhaven National Laboratory (BNL) and at the Physikalisch-Technische Bundesanstalt (PTB), and we have suggested that these oscillations are attributable to some form of solar radiation that has its origin in the deep solar interior. A curious property of the GSI data is that the annual oscillation is much stronger in daytime data than in nighttime data, but the opposite is true for all other oscillations. This may be a systematic effect but, if it is not, this property should help narrow the theoretical options for the mechanism responsible for decay-rate variability.Comment: 9 pages, 21 figure