[Triumf-seminars] TRIUMF Seminar today at 14:00

[TRIUMF Seminars]

Date/Time: Thu 2011-09-15 at 14:00

Location:  Auditorium          

Speaker:   Harry Lipkin (Weizmann Institute)

Title:     The three CP violation puzzles in charmless strange B decays into Kpi: Resolution by introducing the Pauli Principle

Abstract: Puzzle # 1. Direct CP violation is observed in K-pi decays of neutral B mesons, not seen in K-pi decays of charged B mesons. The neutral and charged B meson states differ only in the flavor of the spectator quark which does not participate in weak interactioon. Why should changing its flavor make a difference?

Puzzle # 2. Experimental relations not predicted by standard treatments are observed. New experimental branching ratio data show a contradiction in isospin relations: 1. Agreement with pure I=1/2 amplitude predicted by a penguin diagram for individual branching ratios in charged and neutral B decays. 2. Disagreement with pure I=1/2 penguin relation between charged and neutral decays. This contrast is not predicted in the standard treatments using independent color-favored and color-suppressed amplitudes.

Both puzzles are resolved by introducing the Pauli principle not included in standard treatments. CPT invariance tells us that direct CP violation can only arise from interference between two amplitdes having different strong and weak phases. K-pi decays are dominated  by the penguin diagram. CP violation can arise from interference between the dominant penguin and smaller tree amplitudes. 

A two-pseudscalar state produced by the decay of a spin zero state has no orbital angular momenta. Two identical u quarks in a relative s-wave must satisfy the Pauli principle. Both puzzles 1 and 2 are resolved by introducing an extreme Pauli blocking constraint which deletes all amplitudes containing two identical quarks in the final state. The tree diagram produces a u-flavored quark from the weak interaction vertex. This amplitude is Pauli blocked in charged B decays where the spectator quark is also a u flavored quark. If the tree diagram is blocked there is no tree-penguin interference and no CP violation. In neutral B decays the spectator quark is a d-flavored quark, there are no identical quark pairs, no blocking and tree-penguin interference can produce CP violation.   

Puzzle # 3. SU(3) relations between tree diagrams for charged B decays into K-pi and pi-pi final states disagree with experiment. Both diagrams have two identical $u$ quarks in the final state. Decays into Kpi are experimentally observed to be Pauli blocked; pipi  decays are not Pauli blocked. This puzzle is resolved by introducing spin and color degrees of freedom. Amplitudes containing two identical quarks are blocked only if the two quarks are in the same color-spin state. Detailed color-spin analysis shows Pauli blocking only in K-pi final state and no blocking in pi-pi.

Stimulants available 15 minutes before the talk.

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