CP Violation in Fermion Pair Decays of Neutral Boson Particles

发布时间：

OZ-93/22,UM-P-93/89,OITS519
CPViolationinFermionPairDecaysofNeutralBosonParticles
3
991tcO71v3420139/hp-pe:hviXraXiao-GangHe1,J.P.Ma2andBruceMcKellar2
1Institute
ofTheoreticalScience
UniversityofOregonEugene,OR97403,USA
and
2Research
CenterforHighEnergyPhysicsSchoolofPhysics
UniversityofMelbourneParkville,Vic.3052Australia
(October,1993
Abstract
WestudyCPviolationinfermionpairdecaysofneutralbosonparticleswithspin0or1.WestudyanewasymmetrytomeasureCPviolationinη,KL→µ+µ−decaysanddiscussthepossibilityofmeasuringitexperimentally.Forthespin-1particlescase,westudyCPviolationinthedecaysofJ/ψtoSU(3octetbaryonpairs.WeshowthatthesedecayscanbeusedtoputstringentconstraintsontheelectricdipolemomentsofΛ,ΣandΞ.11.30.Er,13.25+m,14.20.Jn,14.40.Gx
TypesetusingREVTEX
1

I.INTRODUCTION
CPviolationhasonlybeenobservedintheneutralKaonsystem[1].Inordertoisolatethesource(orsourcesresponsibleforCPviolation,itisimportanttofindCPviolationinothersystems.InthispaperwestudyCPviolationinfermionpairdecaysofaneutralbosonparticle,whichisaCPeigenstateandhasspin-0(Sorspin-1(V.¯aS→ff
¯canThemostgeneraldecayamplitudeforSdecaysintoapairofspin-1/2particlesffbeparametrizedas
¯=uM(S→ff¯f(p1,s1(aS+iγ5bSvf¯(p2,s2,
(1
whereaSandbSareingeneralcomplexnumbers.IfbothaSandbSarenonzero,CPis¯,wherethef(f¯isviolated.OnecandefineadensitymatrixRfortheprocessS→ff
¯polarizedandthepolarizationisdescribedbyaunitpolarizationvectors1(2inthef(frestframe.Withtheamplitudeineq.(1theCPviolatingpartofthedensitymatrixintherestframeofSisgivenby
∗RCP=Nf{Im(aSb∗Sp·(s1−s2−Re(aSbSp·(s1×s2},
(2
whereNfisanormalizationconstant,andpisthethreemomentumofthefermionf.RCPcontainsallinformationaboutCPviolationinthedecay.TheexpectationvaluesofCPoddandCPToddobservablesareproportionaltoIm(aSb∗S.ThisCPviolatingparametercanbemeasuredbytheasymmetery
A(S=
N+−N−
2
βf|aS|2+|bS|2
=
2βfMSIm(aSb∗S

¯,βf=whereΓfisthedecaywidthforS→ff

CP Violation in Fermion Pair Decays of Neutral Boson Particles

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