The mass difference of the neutral K-mesons and the validity of the pertubation expansion in the theory of weak interactions

1961 ◽  
Vol 22 (2) ◽  
pp. 414-426 ◽  
Author(s):  
J. Nilsson
Keyword(s):  
Weak Interactions ◽  
Mass Difference ◽  
K Mesons

scholarly journals NONFACTORIZABLE CONTRIBUTIONS IN NONLEPTONIC WEAK INTERACTIONS OF K MESONS

2001 ◽  
Vol 16 (09) ◽  
pp. 1605-1630 ◽  
Author(s):  
K. TERASAKI
Keyword(s):  
Short Distance ◽  
Weak Interactions ◽  
Mass Difference ◽  
Long Distance ◽  
Field Algebra ◽  
K Meson ◽  
Distance Effects ◽  
Intermediate States ◽  
Meson Pole ◽  
Existing Data

K→ππ, KL-KS mass difference (Δ mK) and KL→γγ(*) are studied systematically by decomposing their amplitude into a sum of factorizable and nonfactorizable ones. The former is calculated by using the naive factorization while the latter is assumed to be controlled by hadron dynamics. Nonfactorizable amplitudes for the K→ππ decays which are estimated by using a hard pion technique dominates the |ΔI| = ½ amplitude. It is seen that the naively factorized short distance term dominates ΔmK as usual since contributions of pseudoscalar-meson poles and ππ intermediate states as the nonfactorizable long distance effects interfere destructively with each other. The K*-meson pole survives in the KL→γγ decay and plays an important role in the present perspective in contrast with the existing theories which are restricted by the theory of field algebra. The form factor for the Dalitz decays of KL and their rates are compared with the existing data.

scholarly journals Leptonic decays of strange particles - C.E.R.N. work on weak interactions

1965 ◽  
Vol 285 (1401) ◽  
pp. 202-213 ◽  
Keyword(s):  
Weak Interactions ◽  
Mass Difference ◽  
Form Factors ◽  
Strange Particle ◽  
Branching Ratios ◽  
Decay Rates ◽  
Leptonic Decays ◽  
Muon Polarization ◽  
Constant Form ◽  
Three Body

Experimental results on strange particle leptonic decays are summarized and compared with predictions based on the Δ S = + Δ Q , |Δ I | = ½ and Δ S ǂ 2 rules, CP invariance and electron-muon universality. Recent (and still preliminary) results on K 0 1.2 → π ± + e ∓ + v , K + → π + + π ± + e ∓ + v and Ʃ ± → N + ( μ or e ) ± + v are compatible with little (< 10%) or no violation of the Δ S = + Δ Q rule. Three-body leptonic decay rates of K + and K 0 disagree by about two standard deviations with the |Δ I = ½ rule prediction, but the agreement is restored if ca . 10% |Δ I | = 3/2 admixture is allowed. No Δ S = 2, ≡ - → N + e - + v or ≡ 0 → p + e - + v decays have been observed to the level of ca . 1% of the normal decays. All the data are in good agreement with time reversal or CP invariance and with the assumptions that the lepton pair is coupled locally and that electrons and muons behave identically apart from effects of their mass difference. † The branching ratios for the various hyperon leptonic decays and the observed V-A form for A β decay are explained qualitatively by the theory of Cabibbo, for example, but the data are not yet precise enough for a sharp test of the theory. New data on K + → π 0 + ( e or μ ) + + v spectra, branching ratios and muon polarization indicate that the interaction is of the vector form with approximately constant form factors and that the form factor ratio f - / f + is of order 1 or compatible with 0, as in the case of K 0 2 → π ± + e ∓ + v .

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