Presentation on theme: "Francisco Antonio Physics 129 November 23, 2010 Li Zhengdao and Yang Zhenning, 1953."— Presentation transcript:
Francisco Antonio Physics 129 November 23, 2010 Li Zhengdao and Yang Zhenning, 1953
Overview: Experimental History of Kaons Evolving Theory of Kaons with respect to CP Current Technologies, Directions for Kaon Science
Pre-Gellmann and Pais The state of the yet to be conceived “Standard Model” The Neutral Particle, one among the many particles of the 1953 particle extravaganza Late 1950’s: The Intermediate Vector Bosons, courtesy of Yukawa 1964: The quark. 1960-1980’s: Parallel development of Kaons’ and the Standard Model’s main concepts.
The Gellmann-Pais Paper Theoretical proposition that there be a property of strangeness to allow for K 0 K 0 (Eigenstates of Mass) CP|K 0 > = -|K 0 > By CP conservation:K1 and K2 were restricted to 2 and 3 decays, respectively Initially thought to be equivalent to K S and K L Later known as the Eigenstates of Weak Interaction
First Results: Lederman, 1956. 1 10^-10 sec. 2 10^-8 sec. Goal: Kinematically confirming the events were related to a neutral secondary particle. 36 “ Magnet Cloud Chamber Design with Proton Beam incident on target (Brookhaven Bevatron)
Data On the V o Events
Ruling Out the Possibilities
CP Violation After All Cronin and Fitch, 1964. First evidence for Indirect CP Violation. Goal: Measured uncharacteristic 2 decays where only K L = K1 should have existed. Again at the Brookhaven Bevatron, this time with spark chamber detectors
CP Violation: The Contenders Direct CP Violation – Depends on decay process itself, penguin diagrams Indirect CP Violation – related to mixing the eigenstates of mass to form the eigenstates of decay. Weak interactions of ΔS = 1 and superweak interactions of ΔS = 2.
The Weak Interaction Asymmetry in the K 0 /K 0 mixing that created K L and K S no longer equivalent to K2 and K1 respectively. Instead a mixture characterized by of K1 and K2 describe K L and K S in the eigenstate of weak interaction. Result: Time/Space Dependent Oscillation between K L and K S Is a measure of CP violation related to the mixing of K 0 /K 0
The Kobayashi-Maskawa Model of Weak Interaction Instead of a diagonal matrix relating the mass eigenstates to the weak interaction eigenstates, the off diagonals are present, allowing a small amount of mixing The amount of mixing is parametrized by three angles ij and phase shift Weak Interaction EigenstatesMass Eigenstates
Superweak Interactions Asserts that the ONLY CP violation in the neutral Kaon system is due to K 0 /K 0 mixing Would accomplish this by allowing ΔS = 2 so that (for the superweak) is much larger than (from the second order KM weak interaction).
Direct CP Violation Measured! Alavi et. al. 1999, Data: from 96-97 Fermilab Run. Goal: To measure a non-zero Re( / ) to a high degree of accuracy Note that in the case of Superweak models Re( / ) = 0
Alavi Experiment, Fermilab. KTeV Experiment, E832, First to use Dual Kaon Beams for great suppression of unwanted channels
The Modern Kaon Experimental Setup Beam – Dual Kaon Beams Regenerator – Takes advantage of eigenstate oscillations Photon Veto – Rejects 2 and 2 decays. EM Calorimeter – particle “shower”. Reconstruction Magnetic Spectrometer- Phase space measurements (Intensity vs. Momentum) Collimators – maximize neutral beam acceptance.
Is The Superweak Theory disproven? At least in the neutral Kaon system it has been found to be “weak”-sauce. B Systems are currently being tested for similar ratios of Re( / ) with results pending.
Kaon Science Today Direct vs. Indirect CP violation (only Kaons have the former) The Strong CP Problem (QCD doesn’t break CP Symmetry) Matter/Antimatter existence due to preferential decays that violate CP The Standard Model’s take on CP Violation - Insufficient
References Gell-Mann, Pais. “Behavior of Neutral Particles Under Charge Conjugation”. Phys Rev. 97. 1387. Alavi et al. “Observation of Direct CP Violation in Ks,l 2Pi”. Phys Rev. Letters. 83. 22. Cronin et al. “Evidence of the 2Pi Decay of the K2 Meson”. Physical Review Letters. 13. 138. Lande et al. “Observation of Long-Lived Neutral V Particles”. Physical Review. 103. 1901. Kobayashi, Maskawa. “CP-Violation in the Renormalizable Theory of Weak Interaction”. Progress of Theoretical Physics. 49. 652 Biino et al. “The Simultaneous Long and Short lived Neutral Kaon Beams for Experiment NA48”. European Organization for Nuclear Research CERN—SL Division. Winstein. “The Search for Direct CP Violation”. Reviews of Modern Physics. 65. 1113