TITLE:
Constraints on Dark Photon and Dark Z Model Parameters in the B and K Meson Decays
AUTHORS:
Ahmed Rashed
KEYWORDS:
Dark Matter, B-Physics, FCNC
JOURNAL NAME:
Journal of High Energy Physics, Gravitation and Cosmology,
Vol.12 No.2,
March
27,
2026
ABSTRACT: The study investigates flavor-changing neutral current (FCNC) decays of
B
and
K
mesons in the context of a dark
U
(
1
)
D
model with a dark photon/dark
Z
mass between 10 MeV and 2 GeV. While the model improves the fit to certain decay distributions, such as
B→
K
(
∗
)
ℓ
+
ℓ
−
and
B
s
→ϕ
μ
+
μ
−
, it is ruled out by stringent experimental constraints, including atomic parity violation,
K
+
→
μ
+
+invisible
, and
B
s
−
B
¯
s
mixing. To address these constraints, the model is extended with three modifications: allowing additional invisible decays of
Z
D
, introducing a direct vector coupling of
Z
D
to muons, and including a direct coupling of
Z
D
to both muons and electrons, with fine-tuning to cancel the mixing-induced coupling to electrons. Among these extensions, only the third scenario, involving fine-tuned electron coupling, remains consistent with all experimental constraints.