We analyze the spectrum of two- and three-pion states of maximal isospin obtained recently for isosymmetric QCD with pion mass M≈200  MeV in Hörz and Hanlon, [Phys. Rev. Lett. 123, 142002 (2019)PRLTAO0031-900710.1103/PhysRevLett.123.142002]. Using the relativistic three-particle quantization condition, we find ∼2σ evidence for a nonzero value for the contact part of the 3π^{+} (I=3) scattering amplitude. We also compare our results to leading-order chiral perturbation theory. We find good agreement at threshold and some tension in the energy dependent part of the 3π^{+} scattering amplitude. We also find that the 2π^{+} (I=2) spectrum is fit well by an s-wave phase shift that incorporates the expected Adler zero.

中文翻译：

---

从晶格QCD得到的I = 3三点散射振幅。

我们分析了最近在等离子体质量M≈200MeV的等对称QCD中在Hörz和Hanlon中获得的最大同位旋的二和三π态的光谱。牧师 123，142002（2019）PRLTAO0031-900710.1103 / PhysRevLett.123.142002]。使用相对论三粒子量化条件，我们发现3σ^ {+}（I = 3）散射幅度的接触部分的非零值的〜2σ证据。我们还将我们的结果与领先的手性扰动理论进行比较。我们在阈值处发现了良好的一致性，并且在3π^ {+}散射幅度的能量相关部分中发现了一些张力。我们还发现2π^ {+}（I = 2）频谱通过包含预期Adler零的s波相移非常适合。