https://doi.org/10.1140/epjc/s10052-025-15125-6
Regular Article - Theoretical Physics
Ghost-free, gauge invariant SVT generalizations of Horndeski theory
1
Institute for Nuclear Research of the Russian Academy of Sciences, 117312, Moscow, Russia
2
Institute for Theoretical and Mathematical Physics, MSU, 119991, Moscow, Russia
3
NRC, “Kurchatov Institute”, 123182, Moscow, Russia
a
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Received:
24
October
2025
Accepted:
24
November
2025
Published online:
3
December
2025
Abstract
We analyze the generalizations of Kaluza–Klein compactifications of 5D Horndeski theory. They are Scalar–Vector–Tensor (SVT) theories with higher derivatives in the action, but with second order equations of motion. The vector field is invariant under a U(1) gauge transformation and the Scalar–Tensor sector corresponds to Horndeski theory. A subclass of these SVT theories is such that the Horndeski functions 
and 
remain free, while the speed of the tensor and vector modes is exactly the same. We show a subclass where the vector sector retains freedom through new functions of 
while the speed of the vector modes still tracks the speed of the tensor modes.
© The Author(s) 2025
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