This new fourth edition retains the two-volume format，which has been generally well received，with broadly the same allocation of content as in the third edition. The principal new additions are，once again，dictated by substantial new experimental results - namely，in the areas of CP violation and neutrino oscillations，where great progress was made in the first decade of this century. Volume 2 now includes a new chapter devoted to CP violation and oscillations in mesonic and neutrino systems.Partly by way of preparation for this，volume 1 also contains a new chapter，on Lorentz transformations and discrete symmetries.We give a simple do-it-yourself treatment of Lorentz transformations of Dirac spinors，which the reader can connect to the group theory approach in appendix M of volume 2; the transformation properties of bilinear covariants are easily managed. We also introduce Majorana fermions at an early stage.This material is suitable for first courses on relativistic quantum mechanics，and perhaps should have been included in earlier editions （we thank a referee for urging its inclusion now）.To make room for the new chapter in volume 1，the two introductory chapters of the third edition have been condensed into a single one，in the knowledge that excellent introductions to the basic facts of particle physics are available elsewhere. Otherwise，apart from correcting the known minor errors and misprints，the only other changes in volume 1 are some minor improve-ments in presentation，and appropriate updates on experimental numbers.Volume 2 contains significantly more in the way of updates and additions，as will be detailed in the Preface to that volume. But we have continued to omit discussion of speculations going beyond the Standard Model; after all，the cru-cial symmetry-breaking （Higgs） sector has only now become experimentally accessible.

　　伊恩·艾奇森 （Ian J.R. Aitchison）是英國物理學(xué)家，牛津大學(xué)教授，他也是美國SLAC國家加速器實驗室、羅切斯特大學(xué)、華盛頓大學(xué)和歐洲核子研究中心的客座研究員/教授。他還著有《相對論量子力學(xué)》（Relativistic Quantum Mechanics），《規(guī)范場論入門》（An Informal Introduction to Gauge Field Theories），《粒子物理學(xué)中的超對稱性》（Supersymmetry in Particle Physics）等著作。安東尼·海伊 （Anthony J.G. Hey）是微軟研究院學(xué)術(shù)合作部副總裁，負責(zé)微軟公司的全球外部合作研究和技術(shù)計算戰(zhàn)略。他是英國皇家工程院院士，也是英國物理學(xué)會（IOP）、英國計算機學(xué)會（BCS）、國際工程技術(shù)學(xué)會（IET）和國際計算機學(xué)會（ACM）的杰出會士。