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Register a new userMeasurement of branching fraction ratios for $B^+to D^{*+}D^-K^+$, $B^+to D^{*-}D^+K^+$, and $B^0to D^{*-}D^0K^+$ decays
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A measurement of four branching-fraction ratios for three-body decays of $B$ mesons involving two open-charm hadrons in the final state is presented. Run 1 and Run 2 $pp$ collision data are used, recorded by the LHCb experiment at centre-of-mass energies $7$, $8$, and $13$ TeV and corresponding to an integrated luminosity of $9$ fb$^{-1}$. The measured branching-fraction ratios are [ begin{eqnarray} frac{mathcal{B} (B^+to D^{*+}D^-K^+)}{mathcal{B} (B^+to kern 0.2emoverline{kern -0.2em D}{}^0 D^0 K^+)} &=& 0.517 pm 0.015 pm 0.013 pm 0.011 , frac{mathcal{B} (B^+to D^{*-}D^+K^+)}{mathcal{B} (B^+to kern 0.2emoverline{kern -0.2em D}{}^0 D^0 K^+)} &=& 0.577 pm 0.016 pm 0.013 pm 0.013 , frac{mathcal{B} (B^0to D^{*-}D^0K^+)}{mathcal{B} (B^0to D^- D^0 K^+)} &=& 1.754 pm 0.028 pm 0.016 pm 0.035 , frac{mathcal{B} (B^+to D^{*+}D^-K^+)}{mathcal{B} (B^+to D^{*-}D^+K^+)} &=& 0.907 pm 0.033 pm 0.014 ,end{eqnarray} ] where the first of the uncertainties is statistical, the second systematic, and the third is due to the uncertainties on the $D$-meson branching fractions. These are the most accurate measurements of these ratios to date.
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With the advent of the LHC, we will be able to probe New Physics (NP) up to energy scales almost one order of magnitude larger than it has been possible with present accelerator facilities. While direct detection of new particles will be the main avenue to establish the presence of NP at the LHC, indirect searches will provide precious complementary information, since most probably it will not be possible to measure the full spectrum of new particles and their couplings through direct production. In particular, precision measurements and computations in the realm of flavour physics are expected to play a key role in constraining the unknown parameters of the Lagrangian of any NP model emerging from direct searches at the LHC. The aim of Working Group 2 was twofold: on one hand, to provide a coherent, up-to-date picture of the status of flavour physics before the start of the LHC; on the other hand, to initiate activities on the path towards integrating information on NP from high-pT and flavour data.
The only anticipated resonant contributions to $B^+to D^+D^-K^+$ decays are charmonium states in the $D^+D^-$ channel. A model-independent analysis, using LHCb proton-proton collision data taken at centre-of-mass energies of $sqrt{s}=7,8,$ and $13$ TeV, corresponding to a total integrated luminosity of 9 fb$^{-1}$, is carried out to test this hypothesis. The description of the data assuming that resonances only manifest in decays to the $D^+D^-$ pair is shown to be incomplete. This constitutes evidence for a new contribution to the decay, potentially one or more new charm-strange resonances in the $D^-K^+$ channel with masses around 2.9 GeV$/c^2$.
First observations and measurements of the branching fractions of the $bar{B}_s^0to D^+D^-$, $bar{B}_s^0to D_s^+D^-$ and $bar{B}_s^0to D^0bar{D}^0$ decays are presented using 1.0 fb$^{-1}$ of data collected by the LHCb experiment. These branching fractions are normalized to those of $bar{B}^0to D^+D^-$, $B^0to D_s^+D^-$ and $B^-to D^0D_s^-$, respectively. An excess of events consistent with the decay $bar{B}^0to D^0bar{D}^0$ is also seen, and its branching fraction is measured relative to that of $B^-to D^0D_s^-$. Improved measurements of the branching fractions ${cal{B}}(bar{B}_s^0to D_s^+D_s^-)$ and ${cal{B}}(B^-to D^0D_s^-)$ are reported, each relative to ${cal{B}}(B^0to D_s^+D^-)$. The ratios of branching fractions are {-0.2in} {center} {align*} {{cal{B}}(bar{B}_s^0to D^+D^-)over {cal{B}}(bar{B}^0to D^+D^-)} &= 1.08pm 0.20pm0.10, {{cal{B}}(bar{B}_s^0to D_s^+D^-)over {cal{B}}(B^0to D_s^+D^-)} &= 0.050pm 0.008pm0.004, {{cal{B}}(bar{B}_s^0to D^0bar{D}^0)over {cal{B}}(B^-to D^0D_s^-)} &= 0.019pm 0.003pm0.003, {{cal{B}}(bar{B}^0to D^0bar{D}^0)over {cal{B}}(B^-to D^0D_s^-)} &= 0.0014pm 0.0006pm0.0002,{{cal{B}}(bar{B}_s^0to D_s^+D_s^-)over {cal{B}}(B^0to D_s^+D^-)} &= 0.56pm 0.03pm0.04, {{cal{B}}(B^-to D^0D_s^-)over {cal{B}}(B^0to D_s^+D^-)} &= 1.22pm 0.02pm0.07, {align*} {center} oindent where the uncertainties are statistical and systematic, respectively.
The $CP$ asymmetry in $B^-to D_s^-D^0$ and $B^-to D^-D^0$ decays is measured using LHCb data corresponding to an integrated luminosity of 3.0 fb$^{-1}$, collected in $pp$ collisions at centre-of-mass energies of 7 and 8 TeV. The results are $A^{CP}(B^-to D_s^-D^0)=(-0.4pm 0.5pm 0.5)%$ and $A^{CP}(B^-to D^-D^0)=( 2.3pm 2.7pm 0.4)%$, where the first uncertainties are statistical and the second systematic. This is the first measurement of $A^{CP}(B^-to D_s^-D^0)$ and the most precise determination of $A^{CP}(B^-to D^-D^0)$. Neither result shows evidence of $CP$ violation.
Results are reported from an amplitude analysis of the $B^+to D^+D^-K^+$ decay. The analysis is carried out using LHCb proton-proton collision data taken at $sqrt{s}=7,8,$ and $13$ TeV, corresponding to a total integrated luminosity of 9 fb$^{-1}$. In order to obtain a good description of the data, it is found to be necessary to include new spin-0 and spin-1 resonances in the $D^-K^+$ channel with masses around 2.9 GeV$/c^2$, and a new spin-0 charmonium resonance in proximity to the spin-2 $chi_{c2}(3930)$ state. The masses and widths of these resonances are determined, as are the relative contributions of all components in the amplitude model, which additionally include the vector charmonia $psi(3770)$, $psi(4040)$, $psi(4160)$ and $psi(4415)$ states and a nonresonant component.
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