Purely-long-range bound states of He(2s3S)+(2s ^3S)+He(2p3P)(2p ^3P)

We predict the presence and positions of purely-long-range bound states of $^4$He$(2s ^3S)+{}^4$He$(2p ^3P)$ near the $2s ^3S_1+2p ^3P_{0,1}$ atomic limits. The results of the full multichannel and approximate models are compared, and we assess the sensitivity of the bound states to atomic parameters characterizing the potentials. Photoassociation to these purely-long-range molecular bound states may improve the knowledge of the scattering length associated with the collisions of two ultracold spin-polarized $^4$He$(2s ^3S)$ atoms, which is important for studies of Bose-Einstein condensates.Comment: 16 pages, 5 figure

Prospects for precision measurements of atomic helium using direct frequency comb spectroscopy

We analyze several possibilities for precisely measuring electronic transitions in atomic helium by the direct use of phase-stabilized femtosecond frequency combs. Because the comb is self-calibrating and can be shifted into the ultraviolet spectral region via harmonic generation, it offers the prospect of greatly improved accuracy for UV and far-UV transitions. To take advantage of this accuracy an ultracold helium sample is needed. For measurements of the triplet spectrum a magneto-optical trap (MOT) can be used to cool and trap metastable 2^3S state atoms. We analyze schemes for measuring the two-photon $2^3S \to 4^3S$ interval, and for resonant two-photon excitation to high Rydberg states, $2^3S \to 3^3P \to n^3S,D$. We also analyze experiments on the singlet-state spectrum. To accomplish this we propose schemes for producing and trapping ultracold helium in the 1^1S or 2^1S state via intercombination transitions. A particularly intriguing scenario is the possibility of measuring the $1^1S \to 2^1S$ transition with extremely high accuracy by use of two-photon excitation in a magic wavelength trap that operates identically for both states. We predict a ``triple magic wavelength'' at 412 nm that could facilitate numerous experiments on trapped helium atoms, because here the polarizabilities of the 1^1S, 2^1S and 2^3S states are all similar, small, and positive.Comment: Shortened slightly and reformatted for Eur. Phys. J.

Comparison of an increased waist circumference with a positive hydrogen breath test as a clinical predictor of lactose intolerance

ABSTRACT Introduction. Lactose intolerance is a common disease in pediatrics, and its wrong diagnosis will lead to morbidity. The primary objective of this study was to assess the usefulness of an increased waist circumference during the hydrogen breath test as a predictor of lactose intolerance. The secondary objective was to analyze the impact of body mass index, waist circumference measurement, and age on the abdominal distension of patients with lactose intolerance. Population and methods. A total of 138 subjects aged 3 to 15 years were included. They underwent serial measurements of the waist circumference and hydrogen levels in the breath every 30 minutes over 3 hours during the hydrogen breath test. Results. Out of the entire sample, 35 (25.4%) patients had lactose intolerance. An increase of 0.85 cm in waist circumference compared to the baseline waist circumference results in a sensitivity of 88% and a specificity of 85% to predict lactose intolerance (odds ratio: 42.14, 95% confidence interval: 13.08-135.75, p ≤ 0.001). The body mass index and waist circumference measurement did not affect abdominal distension (p= not significant); however, age modified the time of distension. Conclusions. A 0.85 cm increase in waist circumference compared to the baseline waist circumference during the hydrogen breath test is a useful parameter for the diagnosis of lactose intolerance in pediatrics. Variations in relation to body mass index and waist circumference did not affect the usefulness of an increased waist circumference, unlike age. Key words: lactose intolerance, waist circumference, diagnosis, exhaled hydrogen breath, child

Three Body Bound State in Non-Commutative Space

The Bethe-Salpeter equation in non-commutative QED (NCQED) is considered for three-body bound state. We study the non-relativistic limit of this equation in the instantaneous approximation and derive the corresponding Schr\"{o}dinger equation in non-commutative space. It is shown that the experimental data for Helium atom puts an upper bound on the magnitude of the parameter of non-commutativity, $\theta\sim10^{-9}\lambda_e^2$.Comment: 10 pages, 3 figures, to appear in Phys. Rev.

Precision physics of simple atoms: QED tests, nuclear structure and fundamental constants

Quantum electrodynamics is the first successful and still the most successful quantum field theory. Simple atoms, being essentially QED systems, allow highly accurate theoretical predictions. Because of their simple spectra, such atoms have been also efficiently studied experimentally frequently offering the most precisely measured quantities. Our review is devoted to comparison of theory and experiment in the field of precision physics of light simple atoms. In particular, we consider the Lamb shift in the hydrogen atom, the hyperfine structure in hydrogen, deuterium, helium-3 ion, muonium and positronium, as well as a number of other transitions in positronium. Additionally to a spectrum of unperturbed atoms, we consider annihilation decay of positronium and the g factor of bound particles in various two-body atoms. Special attention is paid to the uncertainty of the QED calculations due to the uncalculated higher-order corrections and effects of the nuclear structure. We also discuss applications of simple atoms to determination of several fundamental constants

Precision Atomic Spectroscopy with an Integrated Electro- Optic Modulator and DBR Diode Laser at 1083nm

We have explored the use of recently developed high speed integrated electro optic modulators and DBR diode lasers as a tool for precision laser studies of atoms. In particular, we have developed a technique using a high speed modulator as a key element and applied it to the study of the fine structure of the 23P state of atomic helium. This state has been of long standing interest in atomic physics and its study has been the aim of several recent experiments using various precision techniques. We present our method and results, which will describe a new method for determining the fine structure constant, and lead to a precision test of atomic theory