CP Violation in the Decay $\eta \to {\pi }^{+}{\pi }^{-}\gamma$

Abstract

We study the CP violating effects in the decay of $\eta \to {\pi }^{+}{\pi }^{-}\gamma$. We show that to have CP violation in the decay, one has to consider both linear and circular photon polarizations. In the standard model, the polarizations are vanishingly small. However, model-independently, i.e. using only experimental constraint imposed by the limit on $Br(\eta \to {\pi }^{+}{\pi }^{-})$ it can be up to $O(10$. We also explore various possible operators and we find that the tensor type operator, possibly arising from a nonzero CP violating electric dipole moment of the strange quark, can induce a sizable linear photon polarization.

new references added,accepted for publication in Mod.Phys.Lett

References in corpus (1)

• Observation of CP violation in the B^0 meson system

Cited by in corpus (9)

• Precision tests of fundamental physics with $\eta$ and ${\eta }^{\prime }$ mesons
• The CP-violating asymmetry in η\toπ^+ π^- e^+e^-
• Measurement of the branching ratio and search for a CP violating asymmetry in the eta -> pi+pi-e+e-(gamma) decay at KLOE
• Measurements of Branching Ratios for $\eta$ Decays into Charged Particles
• An overview of $\eta$ and ${\eta }^{\prime }$ decays at BESIII
• Tests of the fundamental symmetries in eta meson decays
• Measurement of the Branching Fraction of and Search for a CP-Violating Asymmetry in ${\eta }^{\prime }\to {\pi }^{+}{\pi }^{-}{e}^{+}{e}^{-}$ at BESIII
• $CP$ violation in ${\eta }^{(\prime )}\to {\pi }^{+}{\pi }^{-}{\mu }^{+}{\mu }^{-}$ decays
• ${\eta }^{{(}^{\prime })}\to {\pi }^{+}{\pi }^{-}{\gamma }^{(\ast )}$ in large-$N_c$ chiral perturbation theory