2025/11/09 by Ahn, Yang Hwan
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph) #High Energy Physics - Theory (hep-th)
paper · doi:10.48550/arxiv.2511.06355
A four-dimensional effective model with G\rm SM× SL(2,ℤ) × U(1)X is proposed in string-derived supergravity framework, where G\rm SM is the Standard Model (SM) gauge group and U(1)X is gauged. We show SL(2,ℤ)- and U(1)X-mixed anomalies should vanish. Anomalies induced by Kähler transformations match those from gaugino chiral rotations. When SM fermions transform nontrivially under SL(2,ℤ), and with vanishing gaugino contributions, the anomaly-free conditions are powerful enough to determine the quark and lepton flavor structures, set scales for U(1)X breaking, and ensure the strong CP phase remains unmodified. While the Green-Schwarz coefficient δ\rm GSX is generically non-zero, vanishing U(1)X anomalies cause gauge boson decoupling and δ\rm GSX→ 0, yielding a massless global U(1)X without a Nambu-Goldstone mode. We show that the modulus vacuum expectation value stabilizes near ⟨τ⟩ ≈ i, where exact SL(2,ℤ) (T-duality) is spontaneously broken, removing residual modular symmetry. The framework predicts seesaw-generated neutrino masses and flavored axion properties, with all Yukawa coefficients constrained to unit-magnitude complex numbers. Our model reproduces current quark and lepton data, predicts an axion mass ma≈0.9×10-2 eV and photon coupling |gaγγ|≈1.7×10-13 \rm GeV-1, and unlike the ordinary case, suppresses flavor-violating axion couplings to s,d quarks and μ,e leptons to O(λ4) (with λ the Cabibbo angle). It also yields normal neutrino mass hierarchy consistent with oscillation data, 0νββ-decay rate, and cosmological and astrophysical measurements.