T-violating Asymmetries
(through 8 February 2015)


T violation asymmetry is measured using triple-product correlations and assuming the validity of the CPT theorem. Triple-product correlations manifest themselves in the observable a • (b × c), where a, b, and c are spins or momenta. This observable is odd under time reversal T.

For example, for the decay mode D0 → K+ K π+ π, the observable CT = PK+ • (Pπ+ × Pπ-) is computed using the momenta of the daughter particles, and is T-odd. The asymmetry
AT ≡ [Γ(CT > 0) − Γ(CT < 0)] / [Γ(CT > 0) + Γ(CT < 0)]

would, in the absence of a strong phase, test for T violation in D0 decays, where the Γ's are partial widths.

The corresponding quantity for D0 is CT = PK- • (Pπ- × Pπ+). Defining the corresponding asymmetry

AT ≡ [Γ(−CT > 0) − Γ(−CT < 0)] / [Γ(−CT > 0) + Γ(−CT < 0)] ,

then the difference in asymmetries
AT viol. ≡ (ATAT)/2

tests for T violation even with nonzero strong phases. T violation asymmetry is a clean and alternative way to search for CP violation in the charm sector.


References:
E. Golowich and G. Valencia, Phys. Rev. D 40, 112 (1989).
I.I. Bigi, Proceedings of KAON2001, 417 (2001).
W. Bensalem and D. London, Phys. Rev. D 64, 116003 (2001).
W. Bensalem et al., Phys. Rev. D 66, 094004 (2002).
W. Bensalem et al., Phys. Lett. B 538, 309 (2002).




T-violating asymmetries in D0 decay-rates

Year Experiment T-violating Asymmetry in the decay mode D0 to K+K-π+π- AT viol. = (ATAT)/2
2014 LHCb R. Aaij et al. (LHCb Collab.), arXiv:1408.1299. +0.0018 ± 0.0029 ± 0.0004
2010 BABAR P. del Amo Sanchez et al. (BABAR Collab.), Phys. Rev. D81, 111103 (2010). +0.0010 ± 0.0051 ± 0.0044
2005 FOCUS J.M. Link et al. (FOCUS Collab.), Phys. Lett. B 622, 239 (2005). +0.010 ± 0.057 ± 0.037
. . COMBOS average +0.0017 ± 0.0027




T-violating asymmetries in D+ decay-rates

Year Experiment T-violating Asymmetry in the decay mode D+ to K0sK+π+π- AT viol. = (ATAT)/2
2011 BABAR J.P. Lees et al. (BABAR Collab.), Phys. Rev. D 84, 031103 (2011). -0.0120 ± 0.0100 ± 0.0046
2005 FOCUS J.M. Link et al. (FOCUS Collab.), Phys. Lett. B 622, 239 (2005). +0.023 ± 0.062 ± 0.022
. . COMBOS average -0.0110 ± 0.0109




T-violating asymmetries in Ds+ decay-rates

Year Experiment T-violating Asymmetry in the decay mode Ds+ to K0sK+π+π- AT viol. = (ATAT)/2
2011 BABAR J.P. Lees et al. (BABAR Collab.), Phys. Rev. D 84, 031103 (2011). -0.0136 ± 0.0077 ± 0.0034
2005 FOCUS J.M. Link et al. (FOCUS Collab.), Phys. Lett. B 622, 239 (2005). -0.036 ± 0.067 ± 0.023
. . COMBOS average -0.0139 ± 0.0084

 


This page is maintained by D. Pedrini and was last updated