Measurement of the ratios of branching fractions $\mathcal{R}(D^{\ast })$ and $\mathcal{R}(D^0)$

Abstract

The ratios of branching fractions $\mathcal{R}(D^{\ast })\equiv \mathcal{B}(\bar{B}\to D^{\ast }{\tau }^{-}{\bar{\nu }}_{\tau })/\mathcal{B}(\bar{B}\to D^{\ast }{\mu }^{-}{\bar{\nu }}_{\mu })$ and $\mathcal{R}(D^0)\equiv \mathcal{B}(B^{-}\to D^0{\tau }^{-}{\bar{\nu }}_{\tau })/\mathcal{B}(B^{-}\to D^0{\mu }^{-}{\bar{\nu }}_{\mu })$ are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to 3.0 fb${}^{-1}$ of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode ${\tau }^{-}\to {\mu }^{-}{\nu }_{\tau }{\bar{\nu }}_{\mu }$. The measured values are $\mathcal{R}(D^{\ast })=0.281\pm 0.018\pm 0.024$ and $\mathcal{R}(D^0)=0.441\pm 0.060\pm 0.066$, where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is $\rho =-0.43$. Results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the Standard Model.

All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-039.html (LHCb public pages)

References in corpus (5)

• PYTHIA 6.4 Physics and Manual
• $R(D^{\ast })$, $|V_{cb}|$, and the Heavy Quark Symmetry relations between form factors
• Measurement of the $\tau$ lepton polarization and $R(D^{\ast })$ in the decay $\bar{B}\to D^{\ast }{\tau }^{-}{\bar{\nu }}_{\tau }$ with one-prong hadronic $\tau$ decays at Belle
• Extraction of $|V_{cb}|$ from $B\to D^{(\ast )}\ell {\nu }_{\ell }$ and the Standard Model predictions of $R(D^{(\ast )})$
• The $V_{cb}$ puzzle: an update

Cited by in corpus (34)

• Global fit to $b\to c\tau \nu$ anomalies as of Spring 2024
• Observation of $D_s^{+}\to {\eta }^{\prime }{\mu }^{+}{\nu }_{\mu }$, Precision Test of Lepton Flavor Universality with $D_s^{+}\to {\eta }^{(\prime )}{\ell }^{+}{\nu }_{\ell }$, and First Measurements of $D_s^{+}\to {\eta }^{(\prime )}{\mu }^{+}{\nu }_{\mu }$ Decay Dynamics
• Measurement of the branching fraction ratios $R(D^{+})$ and $R(D^{\ast +})$ using muonic $\tau$ decays
• Measurement of the $D^{\ast }$ longitudinal polarization in $B^0\to D^{\ast -}{\tau }^{+}{\nu }_{\tau }$ decays
• First Measurement of $R(X_{\tau /\ell })$ as an Inclusive Test of the $b\to c\tau \nu$ Anomaly
• Observation of $D^{+}\to {\eta }^{\prime }{\mu }^{+}{\nu }_{\mu }$ and First Study of $D^{+}\to {\eta }^{\prime }{\ell }^{+}{\nu }_{\ell }$ Decay Dynamics
• Strategy to measure tau $g-2$ via photon fusion in LHC proton collisions
• Test of lepton flavor universality with measurements of $R(D^{+})$ and $R(D^{\ast +})$ using semileptonic $B$ tagging at the Belle II experiment
• Analysis of $b\to c\tau {\bar{\nu }}_{\tau }$ anomalies using weak effective Hamiltonian with complex couplings
• Semileptonic baryon decays ${\Xi }_b\to {\Xi }_c{\ell }^{-}{\bar{\nu }}_{\ell }$ in perturbative QCD
• Search for pair production of scalar and vector leptoquarks decaying to muons and bottom quarks in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Search for charged-lepton-flavour violating $\mu \tau qt$ interactions in top-quark production and decay in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector at the LHC
• Test of lepton flavor universality in semileptonic B${}_{\text{c}}^{+}$ meson decays in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Precise test of lepton flavour universality in $W$-boson decays into muons and electrons in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Flavor phenomenology of an extended 2HDM with inverse seesaw mechanism
• Electric Dipole Moments as Probes of $B$ Anomaly
• Evidence for $B^{-}\to D^{\ast \ast 0}{\tau }^{-}\overline{{\nu }_{\tau }}$ decays
• Search for the lepton-flavor violating decay $B_s^0\to \varphi {\mu }^{\pm }{\tau }^{\mp }$
• Search for charged-lepton flavor violation in the production and decay of top quarks using trilepton final states in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Decay $B_c^{+}\to D_{(s)}^{(\ast )+}{\ell }^{+}{\ell }^{-}$ within covariant confined quark model
• Phenomenological study of a gauged $L_{\mu }-L_{\tau }$ model with a scalar leptoquark
• Searches for $B^0\to K^{+}{\pi }^{-}{\tau }^{+}{\tau }^{-}$ and $B_s^0\to K^{+}{K}^{-}{\tau }^{+}{\tau }^{-}$ decays
• Probing Compressed Mass Spectrum Supersymmetry at the LHC with the Vector Boson Fusion Topology
• Model Dependent Analysis of D_((s))^+ arrows η^((')) l^+ ν_l Decays in Beyond Standard Model
• Novel Model-Independent Approach to Explore New Physics in Five-body Semileptonic Decays
• Search for heavy neutral resonances decaying to tau lepton pairs in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Lepton universality tests and searches for new physics in charged current decays at Belle II
• Search for a neutral gauge boson with nonuniversal fermion couplings in vector boson fusion processes in proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Model-independent unbinned analysis of $B\to K^{\ast }(\to K^{+}{\pi }^{-}){\mu }^{+}{\mu }^{-}$: zeroes, bounds, Wilson coefficients and symmetries
• Flavour Physics at LHCb -- 50 years of the KM paradigm
• Measurement of high-mass $t\bar{t}{\ell }^{+}{\ell }^{-}$ production and lepton flavour universality-inspired effective field theory interpretations at $\sqrt{s}=13$ TeV with the ATLAS detector
• Towards replacing detector simulation with heterogeneous GNNs in flavour physics analyses
• Minimising Event Size, Maximising Physics: Inclusive Particle Isolation for LHCb's Run 3
• Joint LHCb--Belle II Prospects to Constrain New Physics in $B\to D^{(\ast )}\tau \nu$