| Résumé: | <p>Two measurements of CP observables in B<sup>0</sup> → DK<sup>∗0</sup> decays are presented, where D represents a superposition of D<sup>0</sup> and D<sup>0</sup>-bar states. The measurements use samples of proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13 TeV.</p>
<p>The first measurement uses 5 fb<sup>−1</sup> of data with the D meson reconstructed in the two-body final states K<sup>+</sup>π<sup>−</sup>, π<sup>+</sup>K<sup>−</sup>, K<sup>+</sup>K<sup>-</sup>, and π<sup>+</sup>π<sup>−</sup>, and, for the first time, in the four-body final states K<sup>+</sup>π<sup>−</sup>π<sup>+</sup>π<sup>−</sup>, π<sup>+</sup>K<sup>−</sup>π<sup>+</sup>π<sup>-</sup>, and π<sup>+</sup>π<sup>-</sup>π<sup>+</sup>π<sup>−</sup>. First observations of the decays B0 → D(π<sup>+</sup>K−)K∗0 and B0 → D(π<sup>+</sup>π<sup>−</sup>π<sup>+</sup>π−)K∗0 are obtained, and a set of observables comprising yield ratios and asymmetries is studied. The second measurement studies D-meson decays to the three-body final states K<sub>S</sub><sup>0</sup>π+π<sup>−</sup> and K<sub>S</sub><sup>0</sup>K<sup>+</sup>K<sup>−</sup> in a binned Dalitz plot analysis using 9 fb<sup>−1</sup> of data.</p>
<p>The CP observables from both measurements are interpreted together to determine the CP-violating weak phase γ = (77<sup>+8</sup><sub>-9</sub>)◦. This is the world’s most precise determination using only B0-meson decays and is in agreement with the prediction of the Standard Model. The world’s best measurements of the hadronic parameters r_B = 0.258<sup>+0.022</sup><sub>-0.023</sub> and δ<sub>B0</sub> = (200 ± 8)◦ are also presented.</p>
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