论文标题
YAM2：使用顺序二次编程的$ M_2 $变量的另一个库
YAM2: Yet another library for the $M_2$ variables using sequential quadratic programming
论文作者
论文摘要
$ M_2 $变量是通过向Lorentz-Invariant的横向质量提升并明确使用壳体质量关系来设计$ M_ {T2} $的。与简单的运动学变量（例如，可见粒子的不变质量）不同，该变量直接提供了如何计算它们，使用数值算法来进行$ M_2 $变量的计算。从本质上讲，$ M_2 $的计算对应于求解数学优化中受约束的最小化问题，并且该任务存在各种数值方法。我们发现，顺序二次编程方法在计算$ M_2 $方面的性能非常好，并且其数值性能甚至比以$ m_2 $的价格在现有软件包中实现的方法更好。由于我们的研究，我们开发并发布了另一个软件库YAM2，用于使用多种数值算法来计算$ M_2 $变量。
The $M_2$ variables are devised to extend $M_{T2}$ by promoting transverse masses to Lorentz-invariant ones and making explicit use of on-shell mass relations. Unlike simple kinematic variables such as the invariant mass of visible particles, where the variable definitions directly provide how to calculate them, the calculation of the $M_2$ variables is undertaken by employing numerical algorithms. Essentially, the calculation of $M_2$ corresponds to solving a constrained minimization problem in mathematical optimization, and various numerical methods exist for the task. We find that the sequential quadratic programming method performs very well for the calculation of $M_2$, and its numerical performance is even better than the method implemented in the existing software package for $M_2$. As a consequence of our study, we have developed and released yet another software library, YAM2, for calculating the $M_2$ variables using several numerical algorithms.
