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arXiv:0803.2445

Dispelling the antihydrogen myth

Guido van Hooydonk

Published Mar 17, 2008• 0 citations
arXivHTMLPDF

Abstract

While achiral Bohr atom theory cannot generate Hbar signatures, achiral Heitler-London bond theory can but its Hbar signatures must be detected. We show that the largest spectral signature to probe Hbar is the singlet-triplet splitting of 9,5 eV at r(0)=0,74 Angstrom, observed in the dihydrogen band spectrum. This large Hbar-signature, overlooked for nearly a century, is confirmed with the observed HH potential energy curve. Hbar claims by CERN-based collaborations, seemingly important for the fate and future of Hbar, are premature and must be examined critically.

DOI
10.48550/arxiv.0803.2445

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While achiral Bohr atom theory cannot generate Hbar signatures, achiral Heitler-London bond theory can but its Hbar signatures must be detected. We show that the largest spectral signature to probe Hbar is the singlet-triplet splitting of 9,5 eV at r(0)=0,74 Angstrom, observed in the dihydrogen band spectrum. This large Hbar-signature, overlooked for nearly a century, is confirmed with the observed HH potential energy curve. Hbar claims by CERN-based collaborations, seemingly important for the fate and future of Hbar, are premature and must be examined critically.
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The present manuscript revisits one of the earliest approaches to treating molecular systems within the Schrödinger formalism of quantum mechanics: the Heitler-London (HL) model. Originally proposed in 1927 and based on a linear combination of atomic orbitals, the HL model provided a foundational description of covalent bonds and has served as the basis for numerous variational methods. Focusing on the hydrogen molecule, we begin by revisiting the analytical calculations of the original HL model, from which the qualitative physics of bonding and antibonding states can be obtained. Subsequently, we propose including electronic screening effects directly in the original HL wave function. We then compare our proposal with variational quantum Monte Carlo (VQMC) calculations, whose trial wave function allows us to optimize the electronic screening potential as a function of the inter-proton distance. We obtain the bond length, binding energy, and vibrational frequency of the H2_22​ molecule. Beyond revisiting this foundational approach in quantum mechanics, our proposal can serve as improved input for constructing new, but still analytically simple, variational wave functions to describe dissociation or bond formation.
The signature of trapped antihydrogen (H‾\overline{\mathrm{H}}H) atoms is the annihilation signal detected when the magnetic trap that confines the atoms is suddenly switched off. This signal would be difficult to distinguish from the annihilation signal of any trapped p‾\overline{p}p​ that is released when the magnetic trap is switched off. This work deduces the large cyclotron energy ($>$137 eV) required for magnetic trapping of p‾\overline{p}p​, considers the possibility that such p‾\overline{p}p​ are produced, and explores the effectiveness of an electric field applied to clear charged particles from the trapping volume before H‾\overline{\mathrm{H}}H detection. No mechanisms are found that can give a p‾\overline{p}p​ such a large cyclotron energy and allow it to mimic an H‾\overline{\mathrm{H}}H annihilation. The method used to release H‾\overline{\mathrm{H}}H atoms from their magnetic trap without removing the magnetic field gradient that could possibly confine p‾\overline{p}p​ with a high cyclotron energy is also discussed.
In 1898, respectable physicists were permitted to speculate in Nature to an extent that would never be allowed today. Schuster's conjectures about “antiatoms” predate Dirac's prediction of “a new kind of particle, unknown to experimental physics, having the same mass and opposite charge to an electron” by 30 years. This new particle was needed to explain certain additional solutions of Dirac's relativistic version of quantum mechanics. Since them antielectrons (positrons), antiprotons and antineutrons have all been produced and detected. Today there is no known particle for which a corresponding antiparticle has not been observed, although in some cases, such as the photon, particle and antiparticle are identical. Almost a century after Schuster wrote to Nature, it at last appears feasible to synthesise the simplest antiatom, the positron-antiproton bound state known as antihydrogen. The prospect of applying high-precision spectroscopic techniques, perfected on hydrogen, to antihydrogen to test fundamental physical principles, makes antihydrogen much more interesting to the physicist than antigold.
Abstract The energy of interaction of a normal helium atom and one excited to the first triplet or singlet metastable state is calculated over a range of nuclear separations from a0 to 12a0. The Heitler-London method is followed, with inclusion of all non-orthogonality integrals, and using analytic wave functions. Because of identity of the nuclei, g and u states of interaction occur, the energy of the u state having a minimum at about 2·1a0, and a positive maximum of 0·29 and 0·26 eV (for triplet and singlet states respectively) at about 4a0; the g state is entirely repulsive. Comparison is made with experimental evidence for the binding energy of normal and metastable (triplet) atoms. An estimate is made of the second-order dipole-dipole interaction for large separations, and it seems certain that the first-order interaction dominates at least to 12a0. Methods of calculating the necessary integrals are discussed in an appendix.