发表机构
Institute for Solid State Physics, University of Tokyo; Swansea Academy of Advanced Computing, Swansea University; Centre for Quantum Fields and Gravity, Department of Physics, Swansea University; Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya University; Institute of Pure and Applied Sciences, University of Tsukuba; Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK); Interdisciplinary Theoretical & Mathematical Science Program, RIKEN (iTHEMS); Quantinuum K.K.; Quantinuum; Computing Research Center, High Energy Accelerator Research Organization (KEK)（东京大学固体物理研究所; 斯旺西大学高级计算学院; 斯旺西大学物理系量子场论与引力研究中心; 名古屋大学小林-益川粒子宇宙起源研究所; 筑波大学理学院; 高能加速器研究机构粒子核研究本部; 理化学研究所跨学科理论与数学科学项目; Quantinuum株式会社; Quantinuum公司; 高能加速器研究机构计算研究中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究用格点QCD计算八味行走色动力学中的Peskin-Takeuchi S参数，提出新方法并给出S=0.281(5)(17)，预测技术-ρ衰变宽度上限，为BSM模型构建提供约束。
AI 中文摘要
我们使用格点规范理论研究具有八个轻基本费米子的 SU(3) 规范理论（八味 QCD）中的 Peskin-Takeuchi S 参数，该理论是行走色动力学的候选者。我们开发了一种新方法，利用流关联函数的第一时间矩来计算 S，并辅以传统的真空极化方法，得到了一致的结果。有限体积（FV）修正通过多个格点体积的数据以及由手征微扰理论启发的公式进行估计。在最小费米子质量下，单双重态贡献为 S = 0.281(5)(17)，小于按比例放大的 2+1 味 QCD 中的值约 0.35（未扣除标准模型贡献）。然而，与朴素预期相反，一旦包含 FV 修正，S 在较小费米子质量下并不一定被抑制。由此得到的 Gasser-Leutwyler 参数 $L_{10}^r(M_\rho)$ 与真实世界 QCD 中的值相似。我们还确定了矢量介子和轴矢量介子衰变常数 $F_\rho$ 和 $F_{a_1}$。比值 $F_\rho/F_\pi$ 对费米子质量稳定，并与 KSRF 估计一致，意味着 $\rho\pi\pi$ 耦合与真实世界 QCD 中的相似。我们预测技术-ρ 介子衰变为弱玻色子的宽度为 $\Gamma_\rho/M_\rho \lesssim 0.24/N$，其中 N 是弱双重态的数量。我们还发现由 ρ 和 $a_1$ 主导的 Weinberg 谱函数和 Das-Mathur-Okubo 求和规则得到满足，产生的 S 和 $L_{10}^r(M_\rho)$ 与我们的主要结果一致。我们讨论了这对 BSM 模型构建的影响。
英文摘要
We use lattice gauge theory to investigate the Peskin-Takeuchi S parameter in SU(3) gauge theory with eight light fundamental fermions (eight-flavor QCD), a candidate for walking technicolor. We develop a new approach to computing S using the first time moment of current correlators, in addition to the conventional vacuum-polarization method, and obtain consistent results. Finite-volume (FV) corrections are estimated using data at multiple lattice volumes and a formula motivated by chiral perturbation theory. At the smallest fermion mass, the one-doublet contribution is S = 0.281(5)(17), smaller than the value $\sim 0.35$ in scaled-up 2+1-flavor QCD (without subtracting the SM contribution). However, contrary to naive expectations, S toward smaller fermion masses is not necessarily suppressed once FV corrections are included. The resulting Gasser-Leutwyler parameter $L_{10}^r(M_ρ)$ is similar to that in real-world QCD. We also determine the vector and axial-vector meson decay constants, $F_ρ$ and $F_{a_1}$. The ratio $F_ρ/F_π$ is stable against the fermion mass and consistent with the KSRF estimate, implying a $ρππ$ coupling similar to that in real-world QCD. We predict the techni-rho decay width into weak bosons to be $Γ_ρ/M_ρ\lesssim 0.24/N$, where N is the number of weak doublets. We further find that the rho- and $a_1$-dominated Weinberg spectral-function and Das-Mathur-Okubo sum rules are satisfied, yielding S and $L_{10}^r(M_ρ)$ consistent with our main results. We discuss implications for BSM model building.
Comments64 pages, 31 figures
