Measurement of R(D) and R(D*) with a Semileptonic Tagging Method

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F20%3A10423565" target="_blank" >RIV/00216208:11320/20:10423565 - isvavai.cz</a>
Result on the web
<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=QafjB9CjMM" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=QafjB9CjMM</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1103/PhysRevLett.124.161803" target="_blank" >10.1103/PhysRevLett.124.161803</a>

Result language
angličtina
Original language name
Measurement of R(D) and R(D*) with a Semileptonic Tagging Method
Original language description
The experimental results on the ratios of branching fractions R(D) = B((B) over bar -> D tau(-)(nu) over bar (tau))/B((B) over bar -> Dl(-)(nu) over bar (e)) and R(D*) = B((B) over bar -> D*tau(-)(nu) over bar (tau))/B((B) over bar -> D*tau(-)(nu) over bar (e)), where l denotes an electron or a muon, show a long-standing discrepancy with the standard model predictions, and might hint at a violation of lepton flavor universality. We report a new simultaneous measurement of R(D) and R(D*), based on a data sample containing 772 x 10(6) B (B) over bar events recorded at the T(4S) resonance with the Belle detector at the KEKB e(+) e(-) collider. In this analysis the tag-side B meson is reconstructed in a semileptonic decay mode and the signal-side tau is reconstructed in a purely leptonic decay. The measured values are R(D) = 0.307 +/- 0.037 +/- 0.016 and R(D*) = 0.283 +/- 0.018 +/- 0.014, where the first uncertainties are statistical and the second are systematic. These results are in agreement with the standard model predictions within 0.2, 1.1, and 0.8 standard deviations for R(D), R(D*), and their combination, respectively. This work constitutes the most precise measurements of R(D) and R(D*) performed to date as well as the first result for R(D) based on a semileptonic tagging method.
Czech name
—
Czech description
—

Type
Jimp - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
—
OECD FORD branch
10303 - Particles and field physics

Project
<a href="/en/project/LTT17020" target="_blank" >LTT17020: Study of Beyond Standard Model Physics with the International Experiment Belle II in Japan</a>
Continuities
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP) S - Specificky vyzkum na vysokych skolach I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year
2020
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Similar results(10)