First Evidence for <math><mi>cos</mi><mn>2</mn><mi>β</mi><mo>></mo><mn>0</mn></math> and Resolution of the Cabibbo-Kobayashi-Maskawa Quark-Mixing Unitarity Triangle Ambiguity

We present first evidence that the cosine of the CP-violating weak phase 2β is positive, and hence exclude trigonometric multifold solutions of the Cabibbo-Kobayashi-Maskawa (CKM) Unitarity Triangle using a time-dependent Dalitz plot analysis of B0→D(*)h0 with D→KS0π+π− decays, where h0∈{π0,η,ω} 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 ϒ(4S) resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain (471&#177;3)&#215;106BB&#175; pairs recorded by the BABAR detector and (772&#177;11)&#215;106BB&#175; pairs recorded by the Belle detector. The results of the measurement are sin2β=0.80&#177;0.14(stat)&#177;0.06(syst)&#177;0.03(model) and cos2β=0.91&#177;0.22(stat)&#177;0.09(syst)&#177;0.07(model). The result for the direct measurement of the angle β of the CKM Unitarity Triangle is β=[22.5&#177;4.4(stat)&#177;1.2(syst)&#177;0.6(model)]&#176;. The measurement assumes no direct CP violation in B0→D(*)h0 decays. The quoted model uncertainties are due to the composition of the D0→KS0π+π− decay amplitude model, which is newly established by performing a Dalitz plot amplitude analysis using a high-statistics e+e−→cc&#175; data sample. CP violation is observed in B0→D(*)h0 decays at the level of 5.1 standard deviations. The significance for cos2β&gt;0 is 3.7 standard deviations. The trigonometric multifold solution π/2−β=(68.1&#177;0.7)&#176; 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.