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_. u. d. u.  e. e . W links members of the same weak isodoublet. W -. within a single generation. u. d. The decay conserves charge, but does NOT conserve iso-spin ( up ness/ down ness). d. _. u. d. u.  e. e . W -. However, we even observe some

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  1. _ u d u e e W links members of the same weak isodoublet W- within a single generation u d The decay conserves charge, but does NOT conserve iso-spin (upness/downness) d

  2. _ u d u e e W- However, we even observe some strangeness-changing weak decays! u d d _ u d u d s u u _ d u s u s d s s s

  3. _ νe m- W- _ K- → - + ν 63.43% of all kaon decays u s K- → 0 +   21.13% _ → e- + νe 0.0000155% p0 u u d p- u W- u s K-

  4. _ u d u e e W- u d d u d u d s u _ _ u u s d W- W- u s d s s s

  5. Cabibbo(1963) Glashow, Illiopoulous, Maiani [GIM](1970) Kobayashi & Maskawa [KM](1973) Suggested the eigenstates of the weak interaction operators (which couple to Ws) are not exactly the same as the “mass” eigenstates participating in the STRONG interactions (free space states) The weak eigenstates are QUANTUM MECHANICAL admixtures of the mass eigenstates dweak= c1d + c2s where, of coursec12 + c22 = 1 = sinθcd + cosθcs

  6. To explain strangeness-changing decays, Cabibbo(1963) introduced the redefined weak iso-doublet u dc u Intended to couple to the Jweak current in the Lagrangian = dcosc + ssinc u u W- W- cosc sinc d s “suppressed” sinc 0.225 cosc  0.974 θc13.1o

  7. The relevant term, JweakWm , then comes from: † † † YR 2 †  - ig1 B W3mW1m-iW2m W1m+iW2m-W3m † † W3m0 0 -W3m 0W1m-iW2m W1m+iW2m 0 † † +

  8. From which follows a NEUTRAL COUPLING to _ _ = uu - dcdc a coupling to a strangeness changing neutral current! p+ m+ m- m+m- u d Z0 Z0 d s u s K0 K+

  9. BUT we do NOT observe processes like: p+ Though we do see the very similar processes: m+m- u d p0 nmm- u u Z0 W- u s K+ Also e+e- u s m- K+ m+ nm m+ m- W- W+ u Z0 These are suppressed, but allowed (observed). d s d s K0 K0 Compare to 0e+e- 0

  10. Glashow, Illiopoulous, Maiani [GIM](1970) even before charmed particles were discovered (1974) and the new quark identified, proposed there could be a 2nd weak doublet that followed and complemented the Cabibbo pattern: So that the meaured Cabibbo “angle” actually represented a mixing/rotation! so that: orthogonal!

  11. then together these doublets produce interactions of: _ _ _ _ uu – dcdc + cc-scsc _ _ _ _ = uu + cc – (dcdc + scsc) _ _ _ _ = uu + cc – (ddcos2θc+ sinθccosθc (ds + sd) + sssin2θc _ _ _ _ ddsin2θc- sinθccosθc (ds + sd) + sscos2θc) _ _ _ _ = uu + cc – dd – ss absolutely NOflavor-changing neutral current terms!

  12. 1965Gellmann & Pais Noticed the Cabibbo mechanism, where was the weak eigenstate, allowed a 2nd order (~rare) weak interaction that could potentially induce the strangeness-violating transition of KoKo a particle becoming its own antiparticle! Ko Ko s s d d u u u W- W+ W- u s s d d Ko Ko

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