Speaker
Mr
Apostolos Tsampodimos
(FTMC)
Description
We study the effects of general disformal metric transformations on fermionic fields, showing that the Dirac action acquires additional kinetic and axial-current couplings. When the sourcing field takes a nontrivial background value, apparent Lorentz-violating effects arise, which we classify within an effective field theory. For scalar and vector ultralight dark matter, precision tests of rotation and boost invariance place stringent constraints on the couplings. We further derive consistency conditions requiring the absence of ghost degrees of freedom, which for multi-scalar transformations demands a degenerate field-space metric, yielding consistent two-field modified gravity models.
Authors
Mr
Apostolos Tsampodimos
(FTMC)
Dr
Fiona Kirk
(LUH & PTB)
Dr
Nathaniel Sherrill
(LUH)
Dr
Guillem Domènech Fuertes
(LUH & AEI)
Dr
Alexander Ganz
(LUH)