论文标题

使用扭曲的质量费米子的短时和中间时间距离耐度磁力贡献的晶格计算

Lattice calculation of the short and intermediate time-distance hadronic vacuum polarization contributions to the muon magnetic moment using twisted-mass fermions

论文作者

Alexandrou, C., Bacchio, S., Dimopoulos, P., Finkenrath, J., Frezzotti, R., Gagliardi, G., Garofalo, M., Hadjiyiannakou, K., Kostrzewa, B., Jansen, K., Lubicz, V., Petschlies, M., Sanfilippo, F., Simula, S., Urbach, C., Wenger, U.

论文摘要

我们介绍了对MUON异常磁矩的贡献的晶格确定(HVP)在所谓的短且中间的时间限制窗口中,$a_μ^{\ rm hvp} $,$a_μ^{\ rm sd} $ a__ sd} $,$ a______________ RBC/UKQCD合作[1]。我们采用了由$ n_f = 2 + 1 + 1 $ n_f = 2 + 1 + 1 $ Wilson-Clover Twisted-Mass夸克的口味的扩展扭曲质量协作(ETMC)产生的量规合奏,其中所有动态夸克风味都接近其物理价值。模拟的晶格间距的三个值等于$ \ simeq 0.057、0.068 $和$ 0.080 $ fm,空间晶格尺寸高达$ l \ simeq 7.6 $ 〜fm。对于短距离窗口,我们将获得$a_μ^{\ rm sd}({\ rm etmc})= 69.27 \,(34)\ cdot 10^{ - 10} $,这与$a_μ^{\ rm sd}(\ rm sd}(\ rm sd}(e^+ e^+ e^+ e^ - )= 68.48.4的最新分散值是一致的。 10^{ - 10} $ [2]。 In the case of the intermediate window we get the value $a_μ^{\rm W}({\rm ETMC}) = 236.3\,(1.3) \cdot 10^{-10}$, which is consistent with the result $a_μ^{\rm W}({\rm BMW}) = 236.7\,(1.4) \cdot 10^{ - 10} $ [3]由宝马协作以及$a_μ^{\ rm w}的Cls/mainz组最近确定({\ rm cls})= 237.30 \,(1.46)\ cdot 10^{ - 10} { - 10} $ [4]。但是,它大于$a_μ^{\ rm w}的分散结果(e^+ e^ - )= 229.4 \,(1.4)\ cdot 10^{ - 10} $ [2],大约$ 3.6 $标准偏差。如果我们平均使用BMW和CLS/MAINZ的ETMC结果,则张力将增加到约4.5美元的标准偏差。我们的准确晶格导致短暂和中间的窗口指向$ e^+ e^ - $横截面数据在低和中间能量区域中的标准模型预测方面的偏差,但在高能量区域中却没有。

We present a lattice determination of the leading-order hadronic vacuum polarization (HVP) contribution to the muon anomalous magnetic moment, $a_μ^{\rm HVP}$, in the so-called short and intermediate time-distance windows, $a_μ^{\rm SD}$ and $a_μ^{\rm W}$, defined by the RBC/UKQCD Collaboration [1]. We employ gauge ensembles produced by the Extended Twisted Mass Collaboration (ETMC) with $N_f = 2 + 1 + 1$ flavors of Wilson-clover twisted-mass quarks with masses of all the dynamical quark flavors tuned close to their physical values. The simulations are carried out at three values of the lattice spacing equal to $\simeq 0.057, 0.068$ and $0.080$ fm with spatial lattice sizes up to $L \simeq 7.6$~fm. For the short distance window we obtain $a_μ^{\rm SD}({\rm ETMC}) = 69.27\,(34) \cdot 10^{-10}$, which is consistent with the recent dispersive value of $a_μ^{\rm SD}(e^+ e^-) = 68.4\,(5) \cdot 10^{-10}$ [2]. In the case of the intermediate window we get the value $a_μ^{\rm W}({\rm ETMC}) = 236.3\,(1.3) \cdot 10^{-10}$, which is consistent with the result $a_μ^{\rm W}({\rm BMW}) = 236.7\,(1.4) \cdot 10^{-10}$ [3] by the BMW collaboration as well as with the recent determination by the CLS/Mainz group of $a_μ^{\rm W}({\rm CLS}) = 237.30\,(1.46) \cdot 10^{-10}$ [4]. However, it is larger than the dispersive result of $a_μ^{\rm W}(e^+ e^-) = 229.4\,(1.4) \cdot 10^{-10}$ [2] by approximately $3.6$ standard deviations. The tension increases to approximately $4.5$ standard deviations if we average our ETMC result with those by BMW and CLS/Mainz. Our accurate lattice results in the short and intermediate windows point to a possible deviation of the $e^+ e^-$ cross section data with respect to Standard Model predictions in the low and intermediate energy regions, but not in the high energy region.

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