I = 2 ππ scattering phase shift from the HAL QCD method with the LapH smearing
I = 2 ππ scattering phase shift from the HAL QCD method with the LapH smearing
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I = 2 ππ 采用 LapH 涂抹的 HAL QCD 方法的散射相移
DOI：
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
K. Sasaki
中科院分区：
文献类型：
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作者：
Daisuke Kawai;S. Aoki;T. Doi;Y. Ikeda;T. Inoue;T. Iritani;N. Ishii;T. Miyamoto;H. Nemura;K. Sasaki
从非定域HAL QCD势计算出的物理可观测性，如散射相移和结合能，并不依赖于用来定义势的汇算符。这就是HAL QCD方法的方案无关性。在实际应用中，采用了非定域势的导数展开式，使得物理可观测量可以在给定展开式的阶数上获得一定的方案依赖性。在本文中，我们比较了点沉格式(HAL QCD方法中的标准格式)和拖尾格式(HAL QCD方法中新引入的LAPH涂抹)所得到的散射相移。虽然不同方案中的势具有不同的预期形式，但我们发现，对于相当小的涂抹尺寸，如果考虑次前级(NLO)项，所产生的散射相移是一致的。我们还发现，在较宽的能量范围内，点沉格式中的HAL QCD势具有可以忽略的NLO项，这意味着在这种情况下导数展开式具有很好的收敛，而涂抹-汇格式中的势具有不可忽略的NLO贡献。简要讨论了这一观测结果对今后研究带有涂抹的全对全传播子的共振通道(如$i=0$和$1$\pi\pi$散射)的意义。本文的所有计算都是在点阵间距为$a\simeq 0.12$Fm($1/a\simeq 1.6$GeV)下进行的，点阵质量为$m_\pi\simeq 870$MeV的点阵为16^3×32$。
Physical observables, such as the scattering phase shifts and the binding energies, calculated from the non-local HAL QCD potential do not depend on the sink operators used to define the potential. This is called the scheme independence of the HAL QCD method. In practical applications, the derivative expansion of the non-local potential is employed, so that physical observables may receive some scheme dependence at given order of the expansion. In this paper, we compare the $I=2$ $\pi\pi$ scattering phase shifts obtained in the point-sink scheme (the standard scheme in the HAL QCD method) and the smeared-sink scheme (the LapH smearing newly introduced in the HAL QCD method). Although potentials in different schemes have different forms as expected, we find that, for reasonably small smearing size, the resultant scattering phase shifts agree with each other if the next-to-leading order (NLO) term is taken into account. We also find that the HAL QCD potential in the point-sink scheme has negligible NLO term for wide range of energies, which implies a good convergence of the derivative expansion in this case, while the potential in the smeared-sink scheme has non-negligible NLO contribution. Implication of this observation to the future studies of resonance channels (such as the $I=0$ and $1$ $\pi\pi$ scatterings) with smeared all-to-all propagators is briefly discussed. All computations in this paper have been performed at the lattice spacing $a\simeq 0.12$ fm ($1/a \simeq 1.6$ GeV) on a $16^3\times 32$ lattice with the pion mass $m_\pi\simeq 870$ MeV.
影响因子：
5
作者：
Xu Feng;K. Jansen;D. Renner
通讯作者：
Xu Feng;K. Jansen;D. Renner