Abstract
Since most probably Standard Model cannot explain large value of CP asymmetries recently observed in D -meson decays the fourth quark-lepton generation explanation of it is proposed. As a byproduct weakly mixed leptons of the fourth generation enable to save the baryon number of the Universe from erasure by sphalerons.
Highlights
Concerning tree amplitudes we found that factorization result differs from the experimental value by factor 1.4 in the case of D → π+π− decay
We determine what value of the ratio of penguin to tree amplitudes of D → π+π− decay is needed to get the observed CP asymmetry
00063-p.8 with good accuracy; concerning the penguin amplitude it appears to be twenty times smaller than one needs to describe the experimental data on ACP
Summary
The talk is based on the paper [1]. In 2011 LHCb collaboration has measured the unexpectedly large CP violating asymmetries in D → π+π− and D → K+K− decays [2]: ΔACLHPCb ≡ ACP(K+K−) − ACP(π+π−) = [−0.82 ± 0.21(stat.) ± 0.11(syst.)]% ,. Comparing with (12) we see that in order to fit the experimental result on ΔACP penguin amplitude should be enhanced by factor 20 in comparison with what factorization gives. Concerning tree amplitudes we found that factorization result differs from the experimental value by factor 1.4 in the case of D → π+π− decay. The numerical value of the penguin amplitude is important in the calculation of CP asymmetries in B → πK and B → ππ decays [7]. In view of the results for B and K decays we can cautiously suppose that for D → π+π− decay factorization calculation underestimate the penguin amplitude by factor 5 at most leading to: ΔACthPeor 0.2%. We will propose the straightforward generalization of the Standard Model in which large CPV in D decays can be explained
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