$\mathit CP$ VIOLATION PARAMETERS

$\alpha $

INSPIRE   PDGID:
S042ALP
For angle $\alpha (\phi _{2}$) of the CKM unitarity triangle, see the review on “$\mathit CP$ violation” in the reviews section.

"OUR EVALUATION" is provided by the Heavy Flavor Averaging Group (HFLAV).

VALUE ($^\circ{}$) DOCUMENT ID TECN  COMMENT
$\bf{ 85.2 {}^{+4.8}_{-4.3}}$ OUR EVALUATION
• • We do not use the following data for averages, fits, limits, etc. • •
$93.7$ $\pm10.6$ 1
VANHOEFER
2016
BELL ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \Upsilon}{(4S)}}$
$84.9$ $\pm13.5$ 1
VANHOEFER
2014
BELL Repl. by VANHOEFER 2016
$79$ $\pm7$ $\pm11$ 2
AUBERT
2010D
 BABR ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \Upsilon}{(4S)}}$
$92.4$ ${}^{+6.0}_{-6.5}$ 1
AUBERT
2009G
 BABR ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \Upsilon}{(4S)}}$
$78.6$ $\pm7.3$ 3
AUBERT
2007O
 BABR ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \Upsilon}{(4S)}}$
$88$ $\pm17$ 4
SOMOV
2006
BELL Repl. by VANHOEFER 2014
$100$ $\pm13$ 5
AUBERT,B
2005C
 BABR Repl. by AUBERT 2009G
$102$ ${}^{+16}_{-12}$ $\pm14$ 6
AUBERT,B
2004R
 BABR Repl. by AUBERT,B 2005C
1  Based on an isospin analysis of the ${{\mathit B}}$ $\rightarrow$ ${{\mathit \rho}}{{\mathit \rho}}$ system.
2  Obtained using the time dependent analysis of ${{\mathit B}^{0}}$ $\rightarrow$ ${{\mathit a}_{{1}}{(1260)}^{\pm}}{{\mathit \pi}^{\mp}}$ and branching fraction measurements of ${{\mathit B}}$ $\rightarrow$ ${{\mathit a}_{{1}}{(1260)}}{{\mathit K}}$ and ${{\mathit B}}$ $\rightarrow$ ${{\mathit K}_{{1}}}{{\mathit \pi}}$ . Uses SU(3) flavor relations.
3  The angle $\alpha _{{\mathrm {eff}}}$ is obtained using the measured $\mathit CP$ parameters of ${{\mathit B}^{0}}$ $\rightarrow$ ${{\mathit a}_{{1}}{(1260)}^{\pm}}{{\mathit \pi}^{\mp}}$ and choosing one of the four solutions that is compatible with the result of SM-based fits.
4  Obtained using isospin relation and selecting a solution closest to the CKM best fit average; the 90$\%$ CL allowed interval is 59$^\circ{}<\phi _{2}$ (${}\equiv\alpha $) $<$ 115$^\circ{}$.
5  Obtained using isospin relation and selecting a solution closest to the CKM best fit average; 90$\%$ CL allowed interval is 79$^\circ{}$ $<$ $\alpha $ $<$ 123$^\circ{}$.
6  Obtained from the measured $\mathit CP$ parameters of the longitudinal polarization by selecting the solution closest to the CKM best fit central value of $\alpha $ = 95$^\circ{}$ $-$ 98$^\circ{}$.
Conservation Laws:
$\mathit CP$ VIOLATION OBSERVED
References:
VANHOEFER 2016
PR D93 032010 Study of ${{\mathit B}^{0}}$ $\rightarrow$ ${{\mathit \rho}^{+}}{{\mathit \rho}^{-}}$ Decays and Implications for the CKM Angle $\phi _{2}$
Also
PR D94 099903 (errat.) Addendum to VANHOEFER 2016 : Study of ${{\mathit B}^{0}}$ $\rightarrow$ ${{\mathit \rho}^{+}}{{\mathit \rho}^{-}}$ Decays and Implications for the CKM Angle $\mathit \phi _{2}$
VANHOEFER 2014
PR D89 072008 Study of ${{\mathit B}^{0}}$ $\rightarrow$ ${{\mathit \rho}^{0}}{{\mathit \rho}^{0}}$ Decays, Implications for the CKM Angle ${{\mathit \phi}_{{2}}}$ and Search for Other ${{\mathit B}^{0}}$ Decay Modes with a Four-Pion Final State
AUBERT 2010D
PR D81 052009 Measurement of Branching Fractions of ${{\mathit B}}$ Decays to ${{\mathit K}_{{1}}{(1270)}}{{\mathit \pi}}$ and ${{\mathit K}_{{1}}{(1400)}}{{\mathit \pi}}$ and Determination of the CKM Angle $\alpha $ from ${{\mathit B}^{0}}$ $\rightarrow$ ${{\mathit a}_{{1}}{(1260)}^{\pm}}{{\mathit \pi}^{\mp}}$
AUBERT 2009G
PRL 102 141802 Improved Measurement of ${{\mathit B}^{+}}$ $\rightarrow$ ${{\mathit \rho}^{+}}{{\mathit \rho}^{0}}$ and Determination of the CKM Angle $\alpha $
AUBERT 2007O
PRL 98 181803 Measurements of $\mathit CP$-Violating Asymmetries in ${{\mathit B}^{0}}$ $\rightarrow$ ${{\mathit a}_{{1}}{(1260)}^{\pm}}{{\mathit \pi}^{\mp}}$ Decays
SOMOV 2006
PRL 96 171801 Measurement of the Branching Fraction, Polarization, and $\mathit CP$ Asymmetry for ${{\mathit B}^{0}}$ $\rightarrow$ ${{\mathit \rho}^{+}}{{\mathit \rho}^{-}}$ Decays, and Determination of the CKM Phase ${{\mathit \phi}_{{2}}}$.
AUBERT,B 2005C
PRL 95 041805 Improved Measurement of the Cabibbo-Kobayashi-Maskawa Angle $\alpha $ using ${{\mathit B}^{0}}$ ${{\overline{\mathit B}}}$ $\rightarrow$ ${{\mathit \rho}^{+}}{{\mathit \rho}^{-}}$ Decays
AUBERT,B 2004R
PRL 93 231801 Study of the Decay ${{\mathit B}^{0}}$ ${{\overline{\mathit B}}^{0}}$ $\rightarrow$ ${{\mathit \rho}^{+}}{{\mathit \rho}^{-}}$ , and Constraints on the Cabbibo-Kobayashi-Maskawa Angle ${{\mathit \alpha}}$