Model-independent bound on the strict massless tensor–pseudotensor interaction

Determine a model-independent strict-M=0 experimental or observational bound on the complete tensor–pseudotensor interaction proportional to the spin-1 coupling product \(g_{\widetilde T}^{X}g_T^{Y}\), including the full \(q^2V_{14}\pm V_{15}\) response rather than relying on a \(V_{15}\)-only limit.

Background

The paper considers a mixed spin-1 pseudotensor–tensor exchange that generates the parity-odd, time-reversal-odd structures q2V9,10q^2V_{9,10} and q2V14±V15q^2V_{14}\pm V_{15}. In the strictly massless limit, obtaining a model-independent constraint requires an experimental analysis sensitive to the complete tensor–pseudotensor potential.

The authors state that existing constraints do not independently cover the complete massless tensor–pseudotensor interaction. Consequently, a limit on the V15V_{15} component alone is insufficient to bound the full coupling product, leaving the requested strict-massless constraint unresolved.

References

Reference also emphasizes that no experimental or observational constraint on the complete massless tensor--pseudotensor $V_{14q+15}$ interaction was available at the time of that review. Hence a model-independent strict-$M=0$ bound on $g_{\widetilde T}Xg_TY$ cannot be obtained by using a $V_{15}$ limit alone.

— Spin-dependent fermion potentials from mixed tensor couplings of massive spin-1 and spin-2 bosons  (2608.30240 - Khadka et al., 31 Aug 2026) in Section “Existing limits and their reinterpretation,” subsection “Spin-1 coupling products”