Adachi, I.; Adye, T.; Ahmed, H.; Ahn, J. K.; Aihara, H.; Kuhr, T.; Ritter, M.; Salehi, M.
(2018):
First Evidence for cos 2 beta > 0 and Resolution of the CabibboKobayashiMaskawa QuarkMixing Unitarity Triangle Ambiguity.
In: Physical Review Letters, Vol. 121, No. 26, 261801

Full text not available from 'Open Access LMU'.
Abstract
We present first evidence that the cosine of the CPviolating weak phase 2 beta is positive, and hence exclude trigonometric multifold solutions of the CabibboKobayashiMaskawa (CKM) Unitarity Triangle using a timedependent Dalitz plot analysis of B0 > D(*) h(0) with D > KS(0)pi(+)pi() decays, where h(0) is an element of {pi(0), eta, omega} denotes a light unflavored and neutral hadron. The measurement is performed combining the final data sets of the BABAR and Belle experiments collected at the (sic)(4S) resonance at the asymmetricenergy B factories PEPII at SLAC and KEKB at KEK, respectively. The data samples contain (471 +/ 3) x 10(6) B (B) over bar pairs recorded by the BABAR detector and (772 +/ 11) x 10(6) B (B) over bar pairs recorded by the Belle detector. The results of the measurement are sin 2 beta = 0.80 +/ 0.14 (stat) +/ 0.06 (syst) +/ 0.03 (model) and cos 2 beta = 0.91 +/ 0.22(stat) +/ 0.09 (syst) +/ 0.07(model). The result for the direct measurement of the angle beta of the CKM Unitarity Triangle is beta = [22.5 +/ 4.4 (stat) +/ 1.2 (syst) +/ 0.6(model)]degrees. The measurement assumes no direct CP violation in B0 > D(*) h(0) decays. The quoted model uncertainties are due to the composition of the D0 > KS(0)pi(+)pi() decay amplitude model, which is newly established by performing a Dalitz plot amplitude analysis using a highstatistics e(+)e() > c (c) over bar data sample. CP violation is observed in B0 > D(*) h(0) decays at the level of 5.1 standard deviations. The significance for cos 2 beta > 0 is 3.7 standard deviations. The trigonometric multifold solution pi/2  beta = (68.1 +/ 0.7)degrees is excluded at the level of 7.3 standard deviations. The measurement resolves an ambiguity in the determination of the apex of the CKM Unitarity Triangle.