Discerning the two $K_1(1270)$ poles in $D^0\to \pi^+ V P$ decay

Abstract

Within the chiral unitary approach, the axial-vector resonance 𝐾1⁡(1270) has been predicted to manifest a two-pole nature. The lowest pole has a mass of 1195 MeV and a width of 246 MeV and couples mostly to 𝐾*⁢𝜋, and the highest pole has a mass of 1284 MeV and a width of 146 MeV and couples mostly to 𝜌⁢𝐾. We analyze theoretically how this double-pole structure can show up in 𝐷0 →𝜋+⁢𝑉⁢𝑃 decays by looking at the vector-pseudoscalar (𝑉⁢𝑃) invariant mass distribution for different 𝑉⁢𝑃 channels, exploiting the fact that each pole couples differently to different 𝑉⁢𝑃 pairs. We find that the final ¯𝐾*⁢𝜋 and 𝜌⁢¯𝐾 channels are sensible to the different poles of the 𝐾1⁡(1270) resonance and hence are suitable reactions to analyze experimentally the double-pole nature of this resonance.