How Positrons "Lock" onto Molecules Before Annihilation, A Study by Prof. Soumen Ghosh, Ahmedabad University

Research led by Ahmedabad University Professor Soumen Ghosh and alumnus Akhil Mundaplackal reveals that complex molecular vibrations—not just simple ones—trap antimatter particles (positrons). Published in Physical Review A, this study, conducted with UC San Diego, provides new evidence on how positrons "lock" onto molecules before annihilation. Read more about this research in the full article shared by Ahmedabad University.

Complex molecular vibrations facilitate the trapping of antimatter particles, enabling distinct binding states that momentarily hold a positron to a molecule before it annihilates. This finding comes from research led by Professor Soumen Ghosh from the School of Arts and Sciences and Ahmedabad University alumnus Akhil Mundaplackal, who contributed to the study as part of his undergraduate thesis. The work involved collaboration with researchers at UC San Diego.

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The research challenges long-standing theoretical assumptions that positron binding occurs primarily through simple, single molecular vibrations. While earlier models acknowledged the presence of multi-quantum vibrations, they assumed they would only contribute to a blurry, continuous background.

When a positron, the antimatter counterpart of an electron, interacts with a molecule, it can be captured into a transient bound state before annihilating. However, the mechanism by which a positron initially "locks" onto the molecule has remained an open question. For decades, standard models suggested that simple vibrations were the primary drivers of this process. However, high-resolution positron beam experiments proved otherwise, demonstrating that positron coupling with multi-quantum vibrations creates discrete, sharp, well-defined capture points.

Titled “Positron–molecule annihilation resonances beyond the fundamental vibrations”, the study has been accepted for publication in Physical Review A, a leading peer-reviewed scientific journal. It provides evidence that complex molecular motions are not merely background effects but play an active role in antimatter interactions.

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