Hemant Kumar Prajapati (IISER, Bhopal) "Chiral $U(1)_{X}$ Gauge Symmetries and Their Phenomenological Implications"

Monday 6 Jul 2026, 15:00 → 16:00 Asia/Seoul

CTPU Seminar room (Theory Bldg, 4F)

While the Standard Model is highly successful, phenomena like dark matter and neutrino oscillations require new physics. A well-motivated remedy is extending the SM with an additional Abelian U(1)_X gauge symmetry. In this talk, I present new chiral U(1)_X extensions of the SM and explore their phenomenological implications across two distinct frameworks. First, I discuss flavor-universal chiral models where anomaly cancellation requires introducing three dark fermions, providing a natural dark matter. The Z′ gauge boson mediates interactions between the dark and visible sectors, and we call this U(1)_X symmetry as the “Dark hypercharge” symmetry. We analyze both heavy (M_{Z′} > M_Z) and light (M_{Z′} < M_Z) Z′ scenarios using collider, CEνNS, and EνES data. I will also discuss how U(1)_X gauge extension can explain the CDF-II W boson mass anomaly. Second, I introduce flavor-specific chiral models that naturally generate mixed vector-axial or pure axial-vector couplings for a light Z′. Using representative benchmarks, we demonstrate that this framework successfully accommodates global fits to b → s observables while respecting B and K meson mixing constraints. Finally, we show how this framework realizes the necessary axial-vector couplings to explain the ATOMKI anomaly while satisfying stringent low-energy and collider bounds.