The asymmetry of antimatter in the proton-猫眼课题宝

DOI：

10.1038/s41586-021-03282-z

发表时间：

2021-02

期刊：

Nature

影响因子：

64.8

通讯作者：

中科院分区：

综合性期刊1区

文献类型：

作者：

J. Dove;B. Kerns;R. McClellan;S. Miyasaka;D. H. Morton;K. Nagai;S. Prasad;F. Sanftl;M. Scott;A. Tadepalli;C. Aidala;J. Arrington;C. Ayuso;C. L. Barker;C. Brown;W. Chang;A. Chen;D. Christian;B. Dannowitz;M. Daugherity;M. Diefenthaler;L. El Fassi;D. Geesaman;R. Gilman;Y. Goto;L. Guo;R. Guo;T. Hague;R. Holt;D. Isenhower;E. Kinney;N. Kitts;A. Klein;D. Kleinjan;Y. Kudo;Ching Him Leung;P. Lin;K. Liu;M. Liu;W. Lorenzon;N. Makins;M. D. de Medeiros;P. McGaughey;Y. Miyachi;I. Mooney;K. Nakahara;K. Nakano;S. Nara;J. Peng;A. Puckett;B. Ramson;P. Reimer;J. Rubin;S. Sawada;T. Sawada;T. Shibata;D. Su;M. Teo;B. Tice;R. Towell;S. Uemura;S. Watson;S. Wang;A. Wickes;J. Wu;Z. Xi;Z. Ye

质子的基本组成部分夸克和胶子几十年前就已经为人所知。然而，对于这些粒子及其动力学如何产生质子的量子束缚态及其物理性质，如自旋，我们仍然有不完整的理论和实验理解。在最简单的图像中，组成质子的两个上夸克和一个下夸克只占质子质量的百分之几，其中大部分以夸克动能和势能以及来自强力的胶子能量的形式存在。这种力的一个基本特征，正如量子色动力学所描述的那样，是它能够在质子内部产生只存在很短时间的物质-反物质夸克对。它们的短暂存在使得质子中的反物质夸克难以研究，但它们的存在在物质-反物质夸克对湮灭的反应中是可以辨别的。在这幅由强相互作用产生夸克-反夸克的图像中，上、下反物质夸克存在的概率分布作为动量的函数应该是几乎相同的，因为它们的质量非常相似，而且与质子的质量相比很小。在这里，我们提供的证据从μ子对生产的测量，这些分布是相当不同的，更丰富的反物质夸克比反物质夸克在一个广泛的动量范围。这些结果预计将恢复对质子中这种反物质不对称起源的几种拟议机制的兴趣，这些机制在以前的结果中不受欢迎，并指出未来的测量可以区分这些机制。

The fundamental building blocks of the proton—quarks and gluons—have been known for decades. However, we still have an incomplete theoretical and experimental understanding of how these particles and their dynamics give rise to the quantum bound state of the proton and its physical properties, such as its spin. The two up quarks and the single down quark that comprise the proton in the simplest picture account only for a few per cent of the proton mass, the bulk of which is in the form of quark kinetic and potential energy and gluon energy from the strong force. An essential feature of this force, as described by quantum chromodynamics, is its ability to create matter–antimatter quark pairs inside the proton that exist only for a very short time. Their fleeting existence makes the antimatter quarks within protons difficult to study, but their existence is discernible in reactions in which a matter–antimatter quark pair annihilates. In this picture of quark–antiquark creation by the strong force, the probability distributions as a function of momentum for the presence of up and down antimatter quarks should be nearly identical, given that their masses are very similar and small compared to the mass of the proton. Here we provide evidence from muon pair production measurements that these distributions are considerably different, with more abundant down antimatter quarks than up antimatter quarks over a wide range of momenta. These results are expected to revive interest in several proposed mechanisms for the origin of this antimatter asymmetry in the proton that had been disfavoured by previous results, and point to future measurements that can distinguish between these mechanisms.

The asymmetry of antimatter in the proton

文献摘要

被引文献

相似文献