Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physical Review A

Hyperfine transitions in ultracold hydrogen-antihydrogen collisions

Alexei Yu. Voronin, Piotr Froelich

Published Jul 30, 2009• 1 citation
Publisher

Abstract

We consider the hyperfine transitions in ultracold collisions of hydrogen (H) and antihydrogen $(\overline{\text{H}})$ atoms. The cross sections for transitions between various spin states are calculated. We show that hyperfine transitions in $\overline{\text{H}}\ensuremath{-}\text{H}$ collisions are basically driven by the strong force between proton and antiproton.

DOI
10.1103/physreva.80.010502

Related papers

Spin exchange in hydrogen–antihydrogen collisions

Alexei Yu. Voronin, Piotr Froelich

We consider the spin-exchange in ultracold collisions of hydrogen ($H$) and antihydrogen ($\bar{H}$) atoms. The cross sections for transitions between various hyperfine states are calculated. We show that the process of spin exchange in $\bar{H}-H$ collisions is basically driven by the strong force between proton and antiproton, that spin-exchange cross-sections are proportional to the difference of singlet and triplet strong force S-wave scattering lengths, while the strong force effects are enhanced about $10^9$ times due to long range atomic forces. We show that any difference in hyperfine structure of $H$ and $\bar{H}$ (CPT violation) manifests itself in radical change of spin-exchange cross-sections energy behavior.

arXiv:0907.4444•Journal of Physics B Atomic Molecular and Optical Physics•Jun 1, 2009•2 citations

Cold collisions of atomic hydrogen with antihydrogen atoms: An optical potential approach

Bernard Zygelman, Alejandro Sáenz, Piotr Froelich +1 more

We present a theory that describes the interaction of hydrogen atoms with antihydrogen at subkelvin temperatures. The formalism includes a nonlocal complex optical potential, whose imaginary component describes the breakup of the $\text{H-}\overline{\mathrm{H}}$ complex into positronium and protonium fragments. Using ab inito methods, we construct the imaginary part of the optical potential and calculate the cross sections for fragmentation in ultracold collisions of $\mathrm{H}$ and $\overline{\mathrm{H}}$. We find a $35%$ reduction in the value of the scattering length from that obtained in the Born-Oppenheimer approximation. We estimate the lifetimes for quasibound states of this complex to fragment into a protonium-positronium pair.

Physical Review A•Apr 20, 2004•43 citations

Resonant phenomena in antihydrogen-hydrogen scattering

Alexei Yu. Voronin, Piotr Froelich

We present a treatment of cold hydrogen-antihydrogen collisions based on the asymptotic properties of atom-antiatom interactions. We derive general formulas for the elastic and inelastic cross sections and for the scattering lengths and analyze their sensitivity to the parameters characterizing the inelasticity of the collision process. Given the inelasticity, we obtain bounds for the complex scattering length. We investigate the influence of strong nuclear forces and the isotope effects in $\text{H}\overline{\text{H}}$ and $\text{D}\overline{\text{H}}$ collisions and demonstrate enhancement of these effects due to the presence of the near-threshold narrow $\text{H}\overline{\text{H}}$ $(\text{D}\overline{\text{H}})$ states. The values of the elastic and inelastic cross sections with simultaneous account of rearrangement and strong forces are presented. General expressions for the (complex) energies of the near-threshold $\text{H}\overline{\text{H}}$ states are obtained.

arXiv:0807.2042•Physical Review A•Feb 19, 2008•10 citations

Stability of hydrogen-antihydrogen mixtures at low energies

S. Jonsell, Alejandro Sáenz, Piotr Froelich +2 more

The stability of antimatter in contact with matter has been investigated. The interaction between hydrogen and antihydrogen is considered as the prototype reaction. We have focused interest on the rates for proton-antiproton and/or electron-positron annihilation during hydrogen-antihydrogen collisions at low energies. In particular, we have concentrated on the calculation of the rates for the rearrangement reaction leading to formation of protonium and positronium, ending inevitably in particle-antiparticle annihilation. The cross section for the rearrangement collision has been calculated in a fully quantum-mechanical treatment. Additionally, we have calculated cross sections for direct annihilation during the collision process, which was found to be comparable to the rearrangement cross section. The elastic cross section and its low-energy limit, given by the scattering length, have been calculated, allowing, by comparison to the inelastic processes, a prediction for the efficiency of cooling antihydrogen via collisions with ultracold hydrogen atoms.

Physical Review A•Oct 12, 2001•78 citations

Electronic spin-flipping collisions of hydrogen atoms

Bernard Zygelman

We present a unified multichannel approach to calculate electron spin-exchange and spin-flipping transition cross sections for collisions of H with H, H with T, and T with T. We use the theory to calculate the hyperfine quenching cross sections for collision energies that range from $1$ mK to thermal temperatures. We show that spin-flipping transitions are induced by the splitting of the $b {}^{3}{\ensuremath{\Sigma}}_{u}$ Born-Oppenheimer potential via the long-range magnetic interactions among electrons. We find that the spin-flipping cross sections in the tritium dimer are about a magnitude larger than that predicted by mass scaling the H-H cross sections. For the former, we show that the spin-exchange cross sections are several magnitudes larger, at cold temperatures, than that of the hydrogen system. We compare the results of the multichannel approach with those obtained using approximate methods such as the degenerate internal-state, the elastic, and Born approximations and discuss their respective range of validity.

Physical Review A•Mar 8, 2010•7 citations

Hydrogen-Antihydrogen Collisions

Piotr Froelich, S. Jonsell, Alejandro Sáenz +2 more

Matter-antimatter interactions are investigated using hydrogen-antihydrogen collisions as an example. Cross sections for elastic scattering and for the antihydrogen loss (either through the rearrangement reaction, resulting in formation of protonium and positronium according to $\mathrm{H}+\overline{\mathrm{H}}\ensuremath{\rightarrow}p\overline{p}{+e}^{+}{e}^{\ensuremath{-}}$, or via annihilation in flight) are calculated for the first time in a fully quantum mechanical approach. Implications for experiments intending to trap and cool antihydrogen are discussed.

Physical Review Letters•May 15, 2000•0 citations
We consider the hyperfine transitions in ultracold collisions of hydrogen (H) and antihydrogen (H‾)(\overline{\text{H}})(H) atoms. The cross sections for transitions between various spin states are calculated. We show that hyperfine transitions in H‾\ensuremath−H\overline{\text{H}}\ensuremath{-}\text{H}H\ensuremath−H collisions are basically driven by the strong force between proton and antiproton.
We consider the spin-exchange in ultracold collisions of hydrogen (HHH) and antihydrogen (Hˉ\bar{H}Hˉ) atoms. The cross sections for transitions between various hyperfine states are calculated. We show that the process of spin exchange in Hˉ−H\bar{H}-HHˉ−H collisions is basically driven by the strong force between proton and antiproton, that spin-exchange cross-sections are proportional to the difference of singlet and triplet strong force S-wave scattering lengths, while the strong force effects are enhanced about 10910^9109 times due to long range atomic forces. We show that any difference in hyperfine structure of HHH and Hˉ\bar{H}Hˉ (CPT violation) manifests itself in radical change of spin-exchange cross-sections energy behavior.
We present a theory that describes the interaction of hydrogen atoms with antihydrogen at subkelvin temperatures. The formalism includes a nonlocal complex optical potential, whose imaginary component describes the breakup of the H-H‾\text{H-}\overline{\mathrm{H}}H-H complex into positronium and protonium fragments. Using ab inito methods, we construct the imaginary part of the optical potential and calculate the cross sections for fragmentation in ultracold collisions of H\mathrm{H}H and H‾\overline{\mathrm{H}}H. We find a 3535%35 reduction in the value of the scattering length from that obtained in the Born-Oppenheimer approximation. We estimate the lifetimes for quasibound states of this complex to fragment into a protonium-positronium pair.
We present a treatment of cold hydrogen-antihydrogen collisions based on the asymptotic properties of atom-antiatom interactions. We derive general formulas for the elastic and inelastic cross sections and for the scattering lengths and analyze their sensitivity to the parameters characterizing the inelasticity of the collision process. Given the inelasticity, we obtain bounds for the complex scattering length. We investigate the influence of strong nuclear forces and the isotope effects in HH‾\text{H}\overline{\text{H}}HH and DH‾\text{D}\overline{\text{H}}DH collisions and demonstrate enhancement of these effects due to the presence of the near-threshold narrow HH‾\text{H}\overline{\text{H}}HH (DH‾)(\text{D}\overline{\text{H}})(DH) states. The values of the elastic and inelastic cross sections with simultaneous account of rearrangement and strong forces are presented. General expressions for the (complex) energies of the near-threshold HH‾\text{H}\overline{\text{H}}HH states are obtained.
The stability of antimatter in contact with matter has been investigated. The interaction between hydrogen and antihydrogen is considered as the prototype reaction. We have focused interest on the rates for proton-antiproton and/or electron-positron annihilation during hydrogen-antihydrogen collisions at low energies. In particular, we have concentrated on the calculation of the rates for the rearrangement reaction leading to formation of protonium and positronium, ending inevitably in particle-antiparticle annihilation. The cross section for the rearrangement collision has been calculated in a fully quantum-mechanical treatment. Additionally, we have calculated cross sections for direct annihilation during the collision process, which was found to be comparable to the rearrangement cross section. The elastic cross section and its low-energy limit, given by the scattering length, have been calculated, allowing, by comparison to the inelastic processes, a prediction for the efficiency of cooling antihydrogen via collisions with ultracold hydrogen atoms.
We present a unified multichannel approach to calculate electron spin-exchange and spin-flipping transition cross sections for collisions of H with H, H with T, and T with T. We use the theory to calculate the hyperfine quenching cross sections for collision energies that range from 111 mK to thermal temperatures. We show that spin-flipping transitions are induced by the splitting of the $b {}^{3}{\ensuremath{\Sigma}}_{u}$ Born-Oppenheimer potential via the long-range magnetic interactions among electrons. We find that the spin-flipping cross sections in the tritium dimer are about a magnitude larger than that predicted by mass scaling the H-H cross sections. For the former, we show that the spin-exchange cross sections are several magnitudes larger, at cold temperatures, than that of the hydrogen system. We compare the results of the multichannel approach with those obtained using approximate methods such as the degenerate internal-state, the elastic, and Born approximations and discuss their respective range of validity.
Matter-antimatter interactions are investigated using hydrogen-antihydrogen collisions as an example. Cross sections for elastic scattering and for the antihydrogen loss (either through the rearrangement reaction, resulting in formation of protonium and positronium according to $\mathrm{H}+\overline{\mathrm{H}}\ensuremath{\rightarrow}p\overline{p}{+e}^{+}{e}^{\ensuremath{-}}$, or via annihilation in flight) are calculated for the first time in a fully quantum mechanical approach. Implications for experiments intending to trap and cool antihydrogen are discussed.