On Searches for CP, T, CPT and C Violation in Flavour-Changing and Flavour-Conserving Interactions

Search forCPandPviolating pseudoscalar decays intoππ

“…[1]. The detection of these decays at any level accessible today would signal P and CP violations from new sources, beyond any considered extension of the SM.…”

“…[1]. Higher branching fractions are possible either by introducing a CP violating term in the QCD lagrangian (a branching fraction up to 10 −17 can be obtained in this scheme)…”

Test of charge conjugation invariance in the decay of theηmeson intoπ+π−π0

“…The quadrant asymmetry tests the C invariance in transition into the 3π final state with I = 2, and the sextant asymmetry is sensitive to the I = 1 [2].…”

Upper limit on the η→π+π− branching ratio with the KLOE detector

“…Higher branching ratios are conceivable either introducing a CP violation term in the QCD lagrangian through the so-called θ term (a branching ratio up to 10 −17 can be obtained in this scheme compatible with the experimental limit on the neutron electric dipole momentum) or allowing a CP violation in the extended Higgs sector (in this case 10 −15 can be reached) as described in Ref. [1]. The detection of this decay at any level accessible today would signal P and CP violation from new sources, beyond any considerable extension of the Standard Model.…”

“…In the Standard Model, the reaction can proceed only via the weak interaction with a branching ratio of order 10 −27 according to Ref. [1]. Higher branching ratios are conceivable either introducing a CP violation term in the QCD lagrangian through the so-called θ term (a branching ratio up to 10 −17 can be obtained in this scheme compatible with the experimental limit on the neutron electric dipole momentum) or allowing a CP violation in the extended Higgs sector (in this case 10 −15 can be reached) as described in Ref.…”