论文标题
SMEFT中的弹性阳性与极端阳性界限
Elastic positivity vs extremal positivity bounds in SMEFT: a case study in transversal electroweak gauge-boson scatterings
论文作者
论文摘要
从量子场理论(QFT)的公理原理得出的阳性界限限制了威尔逊系数的迹象及其在标准模型有效场理论(SMEFT)中的线性组合。但是,随着越来越多的SM模式和操作员被考虑在内,这些界限的确切确定可能变得越来越困难。我们研究了两种旨在为给定的SM领域获得完整界限的方法:1)传统的弹性阳性方法,该方法利用了具有任意超级螺旋的弹性弹性,以及其他量子数量以及2)最大阳性方法,通过构建了允许的系数代表,该方法可以直接使用该系数来构建该系数。以电动仪表孔为例,我们演示了如何以多种方式获得最佳的分析和数值阳性界限。我们进一步比较了约束能力和各种方法的效率,以及它们对更复杂问题的适用性。尽管新的极端方法更受结构的约束,但我们还发现它在分析上易于使用,在数值上比弹性方法快得多,并且当考虑到更多的SM粒子状态和运算符时,它更适用。作为副产品,我们在QFT的公理原理所要求的横向四分光 - 统一玻璃耦合上提供了最佳的阳性界限,并表明它们排除了当前正在LHC上正在搜索的参数空间的$ \%$ \%$。
The positivity bounds, derived from the axiomatic principles of quantum field theory (QFT), constrain the signs of Wilson coefficients and their linear combinations in the Standard Model Effective Field Theory (SMEFT). The precise determination of these bounds, however, can become increasingly difficult as more and more SM modes and operators are taken into account. We study two approaches that aim at obtaining the full set of bounds for a given set of SM fields: 1) the traditional elastic positivity approach, which exploits the elastic scattering amplitudes of states with arbitrarily superposed helicities as well as other quantum numbers, and 2) the newly proposed extremal positivity approach, which constructs the allowed coefficient space directly by using the extremal representation of convex cones. Considering the electroweak gauge-bosons as an example, we demonstrate how the best analytical and numerical positivity bounds can be obtained in several ways. We further compare the constraining power and the efficiency of various approaches, as well as their applicability to more complex problems. While the new extremal approach is more constraining by construction, we also find that it is analytically easier to use, numerically much faster than the elastic approach, and much more applicable when more SM particle states and operators are taken into account. As a byproduct, we provide the best positivity bounds on the transversal quartic-gauge-boson couplings, required by the axiomatic principles of QFT, and show that they exclude $\approx 99.3\%$ of the parameter space currently being searched at the LHC.