Abstract
We present a novel unbinned method to combine B± → DK± and charm threshold data for the amplitude-model unbiased measurement of the CKM angle γ in cases where the D meson decays to a three-body final state. The new unbinned approach avoids any kind of integration over the D Dalitz plot, to make optimal use the available information. We verify the method with simulated signal data where the D decays to KSπ+π−. Using realistic sample sizes, we find that the new method reaches the statistical precision on γ of an unbinned model-dependent fit, i.e. as good as possible and better than the widely used model-independent binned approach, without suffering from biases induced by a mis-modeled D decay amplitude.
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Acknowledgments
J. Lane and E. Gersabeck have received support by the Royal Society (U.K.), J. Rademacker from STFC (U.K.); we express our gratitude. We thank Dr Tim Evans for the development and support of the Amplitude Analysis framework AmpGen [41], upon which our software is built. We thank Prof Marco Gersabeck, Dr Martha Hilton (now at the Institute of Physics (U.K.)), Dr Mark Williams (now at the University of Edinburgh), Dr Florian Reiss, and Dr David Friday from the University of Manchester; Prof Tim Gershon from the University of Warwick; and Jozie Cottee Meldrum from the University of Bristol for their insightful feedback. We are indebted to the participants of the Charming Clues for Existence workshop (2022) at the Munich Institute for Astro and Particle Physics (supported by the German Research Foundation, DFG, project EXC-2094 — 390783311) for helpful comments and discussions.
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Lane, J., Gersabeck, E. & Rademacker, J. A novel unbinned model-independent method to measure the CKM angle γ in B± → DK± decays with optimised precision. J. High Energ. Phys. 2023, 7 (2023). https://doi.org/10.1007/JHEP09(2023)007
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DOI: https://doi.org/10.1007/JHEP09(2023)007