论文标题
来自痕量异常约束的NNLO QCD的扭曲四重为重力形式
Twist-four gravitational form factor at NNLO QCD from trace anomaly constraints
论文作者
论文摘要
众所周知，QCD Energy-Momentum张量$ t^{μν} $中的痕量异常可以归因于每个规范不变的夸克部分的异常和$ t^{μNν} $的gluon部分，并且它们的明确三弹奏格式在$ \ climentized中均已衍生为$ \ climents $ \ cymers c {c。 QCD跟踪异常的此夸克/gluon分解的矩阵元素使我们能够在强子的重力形态上得出QCD的约束，尤其是在扭曲的四个重力形式上，$ \ bar {c} _ {q，g} $。使用三环夸克/gluon跟踪异常公式，我们计算扭转四重力外形要素$ \ bar {c} _ {q，g} $的正向（零动量传递）值，即近代到next to-next-next-to-ne-Leading-rorder-order（nnlo）精度。我们提出了核子和TIC的定量结果，导致对$ \ bar {c} _ {q，g} $的远期值的独立确定。我们发现在核子和亲核之间获得的结果中发现了完全不同的模式。特别是，对于核子，在我们的NNLO公式中产生的非扰动矩阵元件的实验和晶格QCD的当前信息使我们能够准确地预测$ \ bar {c} _ {q，g} $的远期值。
It is known that the trace anomaly in the QCD energy-momentum tensor $T^{μν}$ can be attributed to the anomalies for each of the gauge-invariant quark part and gluon part of $T^{μν}$, and their explicit three-loop formulas have been derived in the $\overline{\rm MS}$ scheme in the dimensional regularization. The matrix elements of this quark/gluon decomposition of the QCD trace anomaly allow us to derive the QCD constraints on the hadron's gravitational form factors, in particular, on the twist-four gravitational form factor, $\bar{C}_{q,g}$. Using the three-loop quark/gluon trace anomaly formulas, we calculate the forward (zero momentum transfer) value of the twist-four gravitational form factor $\bar{C}_{q,g}$ at the next-to-next-to-leading-order (NNLO) accuracy. We present quantitative results for nucleon as well as for pion, leading to a model-independent determination of the forward value of $\bar{C}_{q,g}$. We find quite different pattern in the obtained results between the nucleon and the pion. In particular, for the nucleon, the present information from experiment and lattice QCD on the nonperturbative matrix elements arising in our NNLO formula allows us to obtain a prediction of the forward value of $\bar{C}_{q,g}$ at the accuracy of a few percent level.
