HEAL: Anchored Hyperspherical Equilibrium for Multilingual Safety Alignment

Wenwei Chen, Hongliang Chen, Kun Zhan


Abstract
Safety alignment in large language models is markedly uneven across languages: behaviors learned from English preference data fail to transfer reliably into lower-resource languages, and existing remedies based on per-language preference data or pairwise translation pivots do not scale. We propose Hyperspherical Equilibrium for Aligned Languages (HEAL), a lightweight auxiliary objective that augments any DPO-style alignment pipeline without altering its supervised pairs. HEAL applies two opposing forces to the multilingual representations of the same prompt: a shrink term draws each non-English representation toward a stop-gradient English anchor, while a dilation term repels same-prompt language representations through a pairwise hinge. At equilibrium, representations occupy an English-centered shell-like region that supports cross-lingual transfer while preserving per-language distinctness. Across multiple backbones, HEAL substantially strengthens multilingual safety with the largest gains on the weakest languages, while preserving general capability and showing favorable out-of-distribution behavior on jailbreak evaluation.
Anthology ID:
2026.emnlp-main.1294
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
29463–29472
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1294/
DOI:
Bibkey:
Cite (ACL):
Wenwei Chen, Hongliang Chen, and Kun Zhan. 2026. HEAL: Anchored Hyperspherical Equilibrium for Multilingual Safety Alignment. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 29463–29472, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
HEAL: Anchored Hyperspherical Equilibrium for Multilingual Safety Alignment (Chen et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1294.pdf