Perturbative QCD Prediction of the Hyperon EDM from CP-violating Dipole Interactions

Abstract

Electric dipole moment (EDM) of baryons provides a sensitive probe of CP-violating interactions beyond the Standard Model. Motivated by the recent BESIII measurement on the $Λ$-hyperon EDM [1], we present the first perturbative QCD analysis of the $Λ$ EDM form factor to elucidate its origin in CP-violating quark dipole interactions. In particular, we derive a QCD factorization formula that relates the $Λ$ EDM form factor to quark EDMs and chromo-electric dipole moments (CEDMs) through convolutions with the light-cone distribution amplitudes of $Λ$. These connections allow us to extract constraints on CP-violating dipole couplings from current and future hyperon EDM measurements. Our numerical analysis demonstrates that the $Λ$ EDM exhibits unique sensitivity to the strange-quark CEDM, providing complementary information to that obtained from the neutron EDM.

Figures (2)

• Figure 1: (a). A typical diagram for the contribution from the EDM $d_s$. The photon vertex with a cross-circle is the EDM vertex. (b). A typical diagram for the contribution from the CEDM $\tilde{d}_s$. The gluon vertex with a crossed square represents the CEDM vertex.
• Figure 2: Constraints on the $s$-quark EDM $d_s$ and CEDM $\tilde{d}_s$ from the measurements on the $\Lambda$ and $n$ EDMs.