In recent times, there has been considerable interest in scenarios for quantum gravity in which particle kinematics is affected nonlinearly by the Planck scale, with encouraging results for the phenomenological prospects, but also some concerns that the nonlinearities might produce pathological properties for composite/multiparticle systems. We here focus on kinematics in the κ-Minkowski noncommutative spacetime, the quantum spacetime which has been most studied from this perspective and compare the implications of the alternative descriptions of the total momentum of a multiparticle system which have been so far proposed. We provide evidence suggesting that priority should be given to defining the total momentum as the standard linear sum of the momenta of the particles composing the system. We also uncover a previously unnoticed feature concerning some (minute but conceptually important) effects on center-of-mass motion due to properties of the motion of the constituents relative to the center of mass.

中文翻译：

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量子时空中的多粒子系统和质心运动的新挑战

最近，人们对量子引力的场景产生了相当大的兴趣，其中粒子运动学受到普朗克尺度的非线性影响，在现象学前景方面取得了令人鼓舞的结果，但也有人担心非线性可能会产生复合/多粒子系统的病理性质. 我们在这里专注于运动学κ-Minkowski 非对易时空，从这个角度研究最多的量子时空，并比较了迄今为止提出的多粒子系统总动量的替代描述的含义。我们提供的证据表明，应优先考虑将总动量定义为组成系统的粒子动量的标准线性和。我们还发现了一个先前未被注意到的特征，该特征涉及由于成分相对于质心的运动特性而对质心运动产生的一些（微小但在概念上很重要）影响。