For earlier measurements, beginning with GOOD 1961 and FITCH 1961, see our 1986 edition, Physics Letters 170B 132 (1986).

OUR FIT is described in the note on “$\mathit CP$ violation in ${{\mathit K}_{{{L}}}}$ decays” in the ${{\mathit K}_L^0}$ Particle Listings. The result labeled “OUR FIT Assuming $\mathit CPT$” [``OUR FIT Not assuming $\mathit CPT$''] includes all measurements except those with the comment “Not assuming $\mathit CPT$” [``Assuming $\mathit CPT''$]. Measurements with neither comment do not assume $\mathit CPT$ and enter both fits.

VALUE ($ 10^{10} $ $\hbar{}$ s${}^{-1}$) DOCUMENT ID TECN  COMMENT $\bf{ 0.5289 \pm0.0010}$ OUR FIT  Not assuming $\mathit CPT$ $\bf{ 0.5293 \pm0.0009}$ OUR FIT  Error includes scale factor of 1.3.  Assuming $\mathit CPT$ $0.52797$ $\pm0.00195$ 1, 2 ABOUZAID 2011 KTEV Not assuming $\mathit CPT$ $0.52699$ $\pm0.00123$ 1, 3 ABOUZAID 2011 KTEV Assuming $\mathit CPT$ $0.5240$ $\pm0.0044$ $\pm0.0033$ APOSTOLAKIS 1999 C CPLR ${{\mathit K}^{0}}-{{\overline{\mathit K}}^{0}}$ to ${{\mathit \pi}^{+}}{{\mathit \pi}^{-}}$ $0.5297$ $\pm0.0030$ $\pm0.0022$ 4 SCHWINGENHEUE.. 1995 E773 $20 - 160$ GeV ${{\mathit K}}$ beams $0.5286$ $\pm0.0028$ 5 GIBBONS 1993 E731 Assuming $\mathit CPT$ $0.5257$ $\pm0.0049$ $\pm0.0021$ 4 GIBBONS 1993 C E731 Not assuming $\mathit CPT$ $0.5340$ $\pm0.00255$ $\pm0.0015$ 6 GEWENIGER 1974 C SPEC Gap method $0.5334$ $\pm0.0040$ $\pm0.0015$ 6, 7 GJESDAL 1974 SPEC Assuming $\mathit CPT$ • • We do not use the following data for averages, fits, limits, etc. • • $0.5261$ $\pm0.0015$ 8 ALAVI-HARATI 2003 KTEV Assuming $\mathit CPT$ $0.5288$ $\pm0.0043$ 9 ALAVI-HARATI 2003 KTEV Not assuming $\mathit CPT$ $0.5343$ $\pm0.0063$ $\pm0.0025$ 10 ANGELOPOULOS 2001 CPLR $0.5295$ $\pm0.0020$ $\pm0.0003$ 11 ANGELOPOULOS 1998 D CPLR Assuming $\mathit CPT$ $0.5307$ $\pm0.0013$ 12 ADLER 1996 C RVUE $0.5274$ $\pm0.0029$ $\pm0.0005$ 11 ADLER 1995 CPLR Sup. by ANGELOPOULOS 1998D $0.482$ $\pm0.014$ 13 ARONSON 1982 B SPEC $\mathit E=30-$110 GeV $0.534$ $\pm0.007$ 14 CARNEGIE 1971 ASPK Gap method $0.542$ $\pm0.006$ 14 ARONSON 1970 ASPK Gap method $0.542$ $\pm0.006$ CULLEN 1970 CNTR 1  The two ABOUZAID 2011 values use the same data. The first enters the ''assuming $\mathit CPT$'' fit and the second enters the ''not assuming $\mathit CPT$'' fit. 2  ABOUZAID 2011 fit has $\Delta \mathit m$, ${{\mathit \tau}_{{{s}}}}$, ${{\mathit \phi}_{{{\epsilon}}}}$, Re(${{\mathit \epsilon}^{\,'}}/{{\mathit \epsilon}}$), and Im(${{\mathit \epsilon}^{\,'}}/{{\mathit \epsilon}}$) as free parameters. See Im(${{\mathit \epsilon}^{\,'}}/{{\mathit \epsilon}}$) in the ''${{\mathit K}_L^0}$ $\mathit CP$ violation'' section for correlation information. 3  ABOUZAID 2011 fit has $\Delta \mathit m$ and ${{\mathit \tau}_{{{s}}}}$ free but constrains ${{\mathit \phi}_{{{\epsilon}}}}$ to the Superweak value, i.e. assumes $\mathit CPT$. See ''${{\mathit K}_S^0}$ Mean Life'' section for correlation information. 4  Fits $\Delta \mathit m$ and $\phi _{+−}$ simultaneously. GIBBONS 1993C systematic error is from B.$~$Winstein via private communication. $20 - 160$ GeV ${{\mathit K}}$ beams. 5  GIBBONS 1993 value assume $\phi _{+−}$ = $\phi _{00}$ = $\phi _{{\mathrm {SW}}}$ = ($43.7$ $\pm0.2)^\circ{}$, i.e. assumes $\mathit CPT$. $20 - 160$ GeV ${{\mathit K}}$ beams. 6  These two experiments have a common systematic error due to the uncertainty in the momentum scale, as pointed out in WAHL 1989. 7  GJESDAL 1974 uses charge asymmetry in ${{\mathit K}_{{{{{\mathit \ell}}3}}}^{0}}$ decays. 8  ALAVI-HARATI 2003 fit $\Delta \mathit m$ and ${\mathit \tau}_{{{\mathit K}_S^0} }$ simultaneously. $\phi _{+−}$ is constrained to the Superweak value, i.e. $\mathit CPT$ is assumed. See ``${{\mathit K}_S^0}$ Mean Life'' section for correlation information. Superseded by ABOUZAID 2011. 9  ALAVI-HARATI 2003 fit $\Delta \mathit m$, $\phi _{+−}$, and $\tau _{{{\mathit K}_{{{S}}}}}$ simultaneously. See $\phi _{+−}$ in the ``${{\mathit K}_{{{L}}}}$ $\mathit CP$ violation'' section for correlation information. Superseded by ABOUZAID 2011. 10  ANGELOPOULOS 2001 uses strong interactions strangeness tagging at two different times. 11  Uses ${{\overline{\mathit K}}_{{{e3}}}^{0}}$ and ${{\mathit K}_{{{e3}}}^{0}}$ strangeness tagging at production and decay. Assumes $\mathit CPT$ conservation on $\Delta \mathit S=−\Delta \mathit Q$ transitions. 12  ADLER 1996C is the result of a fit which includes nearly the same data as entered into the ``OUR$~$FIT'' value above. 13  ARONSON 1982 find that $\Delta \mathit m$ may depend on the kaon energy. 14  ARONSON 1970 and CARNEGIE 1971 use ${{\mathit K}_S^0}$ mean life = ($0.862$ $\pm0.006$) $ \times 10^{-10}$ s. We have not attempted to adjust these values for the subsequent change in the ${{\mathit K}_S^0}$ mean life or in $\eta _{+−}$.

Conservation Laws:

$\Delta \mathit S$ = 2 VIA MIXING

References