High statistics study of the K−→π0μ−ν decay

Global effective-field-theory analysis of new-physics effects in (semi)leptonic kaon decays

“…• K 3 shapes: We take the value of log C from the latest Flavianet update [43] and the tensor term for the muonic mode from the ISTRA+ analysis [63]. We assume these bounds will hold in a combined fit, and we neglect the correlations of log C,…”

“…These parameters are customarily fitted to the kinematic distributions of the decay (or Dalitz plot) [63][64][65][66][67][68][69][70], allowing for a calculation the phase-space integral (see next subsection). The Taylor-expansion parametrization introduces a number of parameters which can not be always determined experimentally free of ambiguities and more efficient parametrizations have been proposed [1,11,20,32], incorporating physical constraints to reduce the number of independent parameters.…”

Precision tests of the Standard Model with leptonic and semileptonic kaon decays

“…Dealing with these decays is much harder because: a) -the branching ratio is smaller, resulting in reduced statistics, b) -the E π or t range in the decay is smaller, c) -it is in general harder to obtain an undistorted spectrum and d) -more parameters are necessary. This is quite well evidenced by the wide range of answers obtained by different experiments [48,53,54,52]. Assuming that both scalar and vector FF are given by quadratic polynomials as in Eq.…”

“…Finally, we note that no information concerning the treatment of radiative corrections is given in Ref. [53]. Failure to account for radiative effects could result in a noticeable systematic shift in the slope results.…”

“…For K µ3 decays, recent measurements of the slope parameters (λ ′ + , λ ′′ + , λ 0 ) are available from KTeV [48], KLOE [52], ISTRA+ [53], and NA48 [54]. These data are summarized in Appendix D.…”