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arXiv · 2606.26280

A Circle That Won't Return: The Fate of RR Fluxes and D-branes in Type 0A Tachyon Condensation

Ahmed Rakin Kamal
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Abstract

We study the closed-string tachyon and doubled Ramond-Ramond sector of type 0A in light of the proposed M-theory description on $S^1\vee S^1$-the wedge of two circles joined at a point. In this picture the two RR copies are associated with the two circle components, which we call branches, and tachyon condensation corresponds to shrinking one branch to the type IIA endpoint. From the type 0A equations of motion, we derive the branch-balance condition for a tachyon stationary point and identify the branch-odd RR fluctuation that sources the tachyon around a symmetric background. We then analyze the fate of the collapsing branch RR data as one branch of the wedge collapses to the type IIA endpoint. For an isolated unscreened collapsing-branch $D_p^-$ source, a Gauss-law estimate shows that the long-range RR field-energy cost scales inversely with the shrinking circle and thus becoming infinitely costly, generalizing the $D0^-$-brane decoupling in the original wedge picture. We describe the infrared screening of the relative RR field through an effective higher-form St\"uckelberg mechanism and distinguish this from a possible discharge of localized relative charge. Finally, using standard Wess-Zumino couplings of D-branes, we identify an effective relative-charge carrier and derive a parametric thin-wall criterion for when such a discharge channel $D_p^- \to D_p^+$ can be energetically favored.

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Ahmed Rakin Kamal. 2026-06-24. A Circle That Won't Return: The Fate of RR Fluxes and D-branes in Type 0A Tachyon Condensation. https://arxiv.org/abs/2606.26280

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