Abstract
Measurements of the parameter remain in tension with the standard model prediction, despite recent results helping to close the gap. The standard model prediction it is compared with considers the as an external particle, even though what is detected in experiments is a pair it decays into, from which it is reconstructed. We argue that the experimental result must be compared with the theoretical prediction considering the full four-body decay (). We show that the longitudinal degree of freedom of the off shell helps to further close the disagreement gap with experimental data. We find values for the ratio of and , where the uncertainty comes from the uncertainty of the form factors parameters. Comparing against reduces the gap with the latest LHCb result from to , while the gap with the latest Belle result is reduced from to just and with the world average results from to .
- Received 18 June 2018
DOI:https://doi.org/10.1103/PhysRevD.98.056014
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.
Published by the American Physical Society