When Italian theoretical physicist Ettore Majorana disappeared en route from Palermo to Naples in 1938, he left behind many riddles. Among them was under what circumstances a particle can be its own antiparticle.

当意大利的理论物理学家Ettore Majorana在1938年消失在从巴勒莫到那不勒斯的途中时，他留下了许多不解之谜。其中一个是在什么情况下，一个粒子可以是它自己的反粒子。

Particles and antiparticles are identical except for their opposite electrical charges. Unlike the partner particles of supersymmetry (see "Winos"), antimatter is real - although it only emerged from the realms of conjecture in 1932, when a positively charged anti-electron, or positron, was seen in cosmic rays.

粒子和它的反粒子是相同的，除了它们的电荷相反以外。与超对称建议的超伙伴粒子（请参阅"Winos"）不同，反物质是真实的——虽然它最初时只是出现于1932年该领域的猜想中，在被视为一个带正电的反电子或正电子在宇宙射线中被看到的时候。

Majorana suggested that a chargeless particle belonging to the same group as the electron, the fermions, might have an antiparticle with identical, zero charge. That seems absurd: surely that would just be the same particle twice over? But Majorana's particles are a fixture in a supersymmetric world. There, the chargeless photon has a fermionic superpartner, the photino, which is its own antiparticle. The same goes for the Higgsino, the superpartner of the Higgs boson.

Majorana建议，一个不带荷的和电子同属费米子的粒子，可能有一个相同的零电荷的反粒子。这似乎是荒谬的：这不就是同一个粒子的两次反复吗？但 Majorana粒子本来在超对称世界是肯定有的。没有荷的光子的费米的超对称伙伴，光微子，是它自身的反粒子。同样的是希格斯微子，希格斯玻色子的超对称伙伴。

Something answering Majorana's description also popped up in a lab-bound nanoscale semiconducting wire just last month, confirming a long-standing theoretical prediction. They are quite possibly also passing through our heads every second: neutrinos and antineutrinos seem to interact differently, but might be the same chargeless particle in different states of motion.

同样回答了Majorana描述的实验也出现在上个月，在用纳米半导体导线做实验的实验室里，证实了长期以来的理论预测。它们很可能就在每秒不停的穿过我们的脑袋：中微子和反中微子的反应方式不同，但可能是相同的无荷粒子的不同的运动状态。

The experimental proof might be spotting a nuclear process called neutrinoless double beta decay. Conventional beta decay comes with the emission of an antineutrino or neutrino. In rare cases where a nucleus can undergo two such decays, two of those particles should be emitted. If the neutrino were its own antiparticle, the two would annihilate, and no neutrino emission would be observed. Such processes might in turn shed light on one of the biggest riddles of them all: why it is that matter, rather than antimatter, came to dominate the cosmos.

实验上的证明应该是一个被称为无中微子双β衰变的核过程。传统的β衰变伴随着反中微子或中微子的释放。在罕见的情况下，一个核可以进行两次这样的衰变，放出两个这样的粒子。如果中微子是其自己的反粒子，两者便湮灭，观测不到释放的中微子。这样的过程有助于揭开它们最大的谜团：为什么是物质，而不是反物质，主导了整个宇宙。

• italian [i´tæliən]   a.意大利 n.意大利人   (初中英语单词)
• unlike [,ʌn´laik]   a.不同的 prep.不象...   (初中英语单词)
• partner [´pɑ:tnə]   n.伙伴 v.同....合作   (初中英语单词)
• charge [tʃɑ:dʒ]   v.收费；冲锋 n.费用   (初中英语单词)
• absurd [əb´sə:d]   a.荒谬的，可笑的   (初中英语单词)
• description [di´skripʃən]   n.描写   (初中英语单词)
• undergo [,ʌndə´gəu]   vt.经历(受)；遭受   (初中英语单词)
• particle [´pɑ:tikl]   n.微粒；极小量   (高中英语单词)
• identical [ai´dentikəl]   a.完全相同的   (高中英语单词)
• electrical [i´lektrikəl]   a.用电的；与电有关的   (高中英语单词)
• positively [´pɔzətivli]   ad.确实；断然；绝对   (高中英语单词)
• differently [´difrentli]   ad.不同地，有差别地   (高中英语单词)
• dominate [´dɔmineit]   v.统治；控制；俯视   (高中英语单词)
• naples [´neiplz]   n.那不勒斯   (英语四级单词)
• conjecture [kən´dʒektʃə]   n.&v.猜测(想)；设想   (英语四级单词)
• fixture [´fikstʃə]   n.设备；竞赛项目   (英语四级单词)
• prediction [pri´dikʃən]   n.预告；(气象等)预报   (英语四级单词)
• experimental [ik,speri´mentl]   a.实验的   (英语四级单词)
• conventional [kən´venʃənəl]   a.常规的；协定的   (英语四级单词)
• nucleus [´nju:kliəs]   n.核(心)；细胞核   (英语四级单词)
• annihilate [ə´naiəleit]   vt.歼灭；消灭   (英语四级单词)