英语翻译Quantum electrodynamics (QED),some processes in which we have discussed above,is the prototype quantum field theory.It is characterised by two crucial properties,renormalisability and gauge invariance,which we mention briefly here.Figure

英语翻译Quantum electrodynamics (QED),some processes in which we have discussed above,is the prototype quantum field theory.It is characterised by two crucial properties,renormalisability and gauge invariance,which we mention briefly here.Figure
英语翻译
Quantum electrodynamics (QED),some processes in which we have discussed above,is the prototype quantum field theory.It is characterised by two crucial properties,renormalisability and gauge invariance,which we mention briefly here.Figure 2.1(f) shows a single electron emitting and reabsorbing a virtual photon or a virtual electron-positron pair.The electron line itself in a Feynman diagram represents a “bare” electron ,whereas the real observable particles are the “bare” particles “dressed ” by these virtual processes,the so-called”self-energy” terms which contribute to the mass and charge of the electron that the experimentalist measures.There is no restriction on the momentum k of particles in such virtual states,and such terms are of the form and thus logarithmically divergent.
Divergent terms of this type are present in all QED calculations,e.g.in all the other processes shown in Figure 2.1.Fortunately,it is found possible to redefine the mass or charge as follows.The “bare”mass or charge or (the purely fictitious and unmeasurable value that would obtain in the absence of self-interaction terms )is always found to be multiplied by a dimensionless term containing the divergent integral;since this combination occurs in all calculations,it is therefore replaced by the physical values e,m as determined from experiment.This process is called renormalisation.The procedure is highly technical and beyond the scope of this text.We simply remark that it results in predictions that are,as we have seen ,in incredibly good agreement with experiment.

英语翻译Quantum electrodynamics (QED),some processes in which we have discussed above,is the prototype quantum field theory.It is characterised by two crucial properties,renormalisability and gauge invariance,which we mention briefly here.Figure
分配量电气力学 (QED) ,我们已经讨论上方的一些程序,是原型分配量领域理论.资讯科技是藉着二决定性的财产,renormalisability 和标准度量不变性表示的特色,我们在这里简短地提到.图 2.1(f) 表示单一电子发出而且再吸收一个虚拟的光子或虚拟的电子-阳电子成对.一个 Feynman 图表的电子线本身表现 " 赤裸的 " 电子 ,然而真正的观察得出的粒子是被这些虚拟的程序穿着的 " 赤裸的 " 粒子,那所谓的"自己的-能源"成为块和实验者测量的电子费用的因素期限.没有在如此虚拟的州粒子的动力 k 上的限制,而且如此的期限是形式和如此对数分歧.
这一个类型的分歧期限在所有的 QED 计算中在场,举例来说在所有的另一个中在图 2.1.Fortunately 中处理显示,它是发现可能的依下列各项重新定义块或费用." 使赤裸 " 使或集合要价或 ( 会缺乏自己- 交互作用期限获得的纯粹虚构和无法测量的价值 ) 总是被发现被一个无尺寸的期限繁殖包含分歧的整体；因为这一个组合在所有的计算中发生,它是因此代替被实际的价值 e ,如实验所决定的 m.这一个程序叫做再常态化.程序高度技术上和超过这一个本文的范围.我们只是评论,它造成预测是,如同在与实验的不能采信好的协议中我们已经见到一样.