2014/12/10 中国科学技术大学大一新生《科学与社会》研讨课 《反物质世界的探索》 Cand P&C Pon positronium CPy=(-1)s+w For =0 (S-wave): S=1 量子数 S=0 量子数 P=-1 P=1 C=-1 C=+1 CP=+1 CP=-1 “Ortho-positronium" “Para-positronium" 邦角 Cand P for a photo In QED -photon has J=S=1. -it can convert into a virtual S-wave ete pair for short times S-wave S=1 量子数 photon has same C&Pquantum numbers as an S=1 positronium =-1 G2-1 CP,=+1 物理学院叶邦角教授主讲 版权所有，严禁传播 6
2014/12/10 6 1 )1( ++ S CP + - P =-1 C =-1 CP =+1 S=1 + - P = -1 C =+1 CP =-1 S=0 For ℓ=0 (S-wave): “Ortho-positronium” “Para-positronium” 量子数 量子数 In QED -photon has J=S=1. -it can convert into a virtual S-wave e+e- pair for short times e+ e- S-wave S=1 photon has same C & P quantum numbers as an S=1 positronium P=-1 C=-1 CP=+1 量子数 中国科学技术大学大一新生《科学与社会》研讨课 《反物质世界的探索》 物理学院叶邦角教授主讲 版权所有， 严禁传播 叶邦角主讲
2014/12/10 中国科学技术大学大一新生《科学与社会》研讨课 《反物质世界的探索》 Ortho-positronium annihilation →2 photons? S=1 P-1 C C-1 CP-+1 Initial C=-1>final (-1)(-1) “Ortho-positronium” →3 photons? C= Cs.1 Initial C= 0=-1 郑角主过 Para-positronium annihilation →2 photons? S=0 P=.1 C=+1 Initial C=+1 →final(1(-1=+1 CP=-1 3 photons? “Para-positronium” c1③t+ {C=-1 Initial C=+1→fima面(-10(-1)(1F-1 C=1- 物理学院叶邦角教授主讲 版权所有，严禁传播 7
2014/12/10 7 + - P=-1 C=-1 CP=+1 S=1 “Ortho-positronium” - + 2 photons? C=-1 Initial C =-1 final (-1)(-1) = +1 - + 3 photons? C =-1 Initial C =-1 final (-1)(-1) (-1)= -1 + - P=-1 C=+1 CP=-1 S=0 “Para-positronium” - + 2 photons? C=+1 Initial C=+1 final (-1)(-1) = +1 - + 3 photons? C=+1 Initial C=+1 final (-1)(-1) (-1)= -1 中国科学技术大学大一新生《科学与社会》研讨课 《反物质世界的探索》 物理学院叶邦角教授主讲 版权所有， 严禁传播 叶邦角主讲
2014/12/10 中国科学技术大学大一新生《科学与社会》研讨课 《反物质世界的探索》 Rule for all-photon decays 偶数 C=+1>only even number of photons 奇数 C=-1only odd number of photons 邦角主进 三、CP Violation: Why is it interesting Fundamental:The Martian test C violation does not distinguish between matter/anti-matter.LH/RH are conventions CP distinguishes matter from anti-matter CP says preferred decay Ku->e'ven 物理学院叶邦角教授主讲 版权所有，严禁传播 8
2014/12/10 8 C =+1 only even number of photons C =-1 only odd number of photons 偶数 奇数 三、CP Violation: Why is it interesting ? Fundamental: The Martian test C violation does not distinguish between matter/anti-matter. LH/RH are conventions CP distinguishes matter from anti-matter CP says preferred decay KLe+vep- 中国科学技术大学大一新生《科学与社会》研讨课 《反物质世界的探索》 物理学院叶邦角教授主讲 版权所有， 严禁传播 叶邦角主讲
2014/12/10 中国科学技术大学大一新生《科学与社会》研讨课 《反物质世界的探索》 Charge Inversion --Particle-antiparticle mirror Parity CP Inversion Spatial mirror 郑角主 Is nature left-right symmetric? 1956:The force that is responsible for radioactive decay may not be symmetric under Parity transformation t7列o Yang,Chen-Ning Lee,Tsung-Dao 1956 物理学院叶邦角教授主讲 版权所有，严禁传播 9
2014/12/10 9 17 C P Parity CP Inversion Spatial mirror Charge Inversion Particle-antiparticle mirror Yang, Chen-Ning Lee, Tsung-Dao 1956: The force that is responsible for radioactive decay may not be symmetric under Parity transformation 1956 中国科学技术大学大一新生《科学与社会》研讨课 《反物质世界的探索》 物理学院叶邦角教授主讲 版权所有， 严禁传播 叶邦角主讲
2014/12/10 中国科学技术大学大一新生《科学与社会》研讨课 《反物质世界的探索》 Parity violation discovered WU,Chien Shiung 1912-1997 1956: studied radioactive B-decay of polarized Co6o nuclei: Co60→Ni60ev She found an asymmetry: more electrons are emitted opposite to the nuclear spin direction than along it 邦角 Violation of left-right symmetry the "mirror" BETA RAYS mitted along J direction Mirror world In the "real real world electrons are are different emitted opposite to the J direction L-R symmetry BETA RAYS is violated. (ELECTRONS) THIS WORLD 物理学院叶邦角教授主讲 版权所有，严禁传播 10
2014/12/10 10 WU, Chien Shiung 1912-1997 1956: studied radioactive b-decay of polarized Co60 nuclei: Co60 Ni60 e- n She found an asymmetry: more electrons are emitted opposite to the nuclear spin direction than along it J J In the “real” world electrons are emitted opposite to the J direction In the “mirror” world electrons are emitted along the J direction Mirror world & real world are different L-R symmetry is violated. 中国科学技术大学大一新生《科学与社会》研讨课 《反物质世界的探索》 物理学院叶邦角教授主讲 版权所有， 严禁传播 叶邦角主讲